Fullscreen HTML5Med Res (??MB)HTML4

Monitor & log up to four analog inputs & control four digital outputs from a remote location using a web browser Web We’re very excited about this project. It will let you house your own website with possibly hundreds or even thousands of pages, all in a little box connected to the internet via your modem/router. You don’t need a computer to operate and house a website – this little box does it for you and it can be accessed from anywhere around the world, at any time, even from a mobile phone which has a web browser. In fact, it is a complete web server in a box – so we’ve called it WIB (Web server In a Box). E VERYONE KNOWS THAT web servers normally involve big, expensive, powerful computers with large memory, large hard disks and exotic software, don’t they? Well, that is the normal approach but now it doesn’t have to be. In fact, you don’t 24  Silicon Chip even need a computer! WIB can do it all. Even better, it does not have a hard disk, uses practically no power and costs not much at all. WIB is just a small PC board (singlesided, no less) with a microcontroller, an SD/MMC card reader and not much else. In fact, it involves a total of just three ICs and a 3-terminal regulator. Why have a memory card? This is the “Eureka!” feature: SD/MMC cards are used in the majority of digital cameras and they can pack a huge amount of memory for very little cash; we’ve siliconchip.com.au Pt.1: By MAURO GRASSI WI B Server I n a Box seen them for as little as $8 for four gigs and going down all the time! So for not a lot more money WIB can use an SD/MMC memory card which can be 16 or even 32 gigabytes and that means it can store many thousands of pages of data, pictures or whatever and all of these can be accessed as a website via the internet. Want to change the content? Well you could upload new data remotely via the internet or you could simply whip out the SD card, plug it into your computer and away you go. Or you could have several such SD cards, all with different web formats, presentations or whatever. Maybe you would like to have a large picture library or whatever, accessible via the internet. Of course, siliconchip.com.au you could take the conventional web server approach, as outlined above. Or you could do it with our WIB. In fact, the applications are unlimited. Think of an application involving a website and WIB can probably do it. For example, do you have a small business, perhaps selling goods via the Internet? Maybe WIB could house your website. We’re sure there a lots of applications that have just been waiting for this simple hardware solution. It only requires a modem or a modem/router to connect it to the internet. And while it and the modem will need to be hooked up permanently, its energy use rates as flea power compared to a desktop computer or even a laptop when permanently powered up. Furthermore, WIB can monitor the temperature or any other parameter (just connect a suitable sensor) and it can also be used to control four digital outputs and an RS232 serial port. Down to earth OK, we’ll come clean. While we are very excited about this project, it didn’t start out with such ambitious targets. The original intention was to produce a simple project which could monitor temperature or any other parameter in a home or remote location and display the resultant data on a website. At the same time it could control a few outputs – perhaps switch on a heater or air-conditioner or a few other prosaic functions. But then we had the idea of using November 2009  25 Fig.1: WIB’s home page lets you configure the various functions, including the network, logging, email and FTP settings. It also allows you to read the analog inputs (it’s showing a temperature reading of 27.45°C here) and toggle the digital outputs. You can also send data strings to the serial port. an SD/MMC memory card to store the data and website. And it just grew from there. Having thought of the memory card as the bulk memory for the project and realising just how cheap it was, the potential uses seemed to grow enormously. We are sure readers will come up with a host of different uses. Let’s also be realistic. We need to describe how this WIB project works, how it connects to the internet and all the necessary know-how that this requires. There is a lot of jargon to be digested and understood but when we have finished describing WIB in considerable detail, we are sure that you will see the potential. WIB presents a great learning opportunity for anyone interested in creating a personal website – it will be great for schools, too. For example, it could possibly be teamed up with our popular Seismograph project (SILICON CHIP, September 2005) or a weather station. Students would be able to access it at any time via a mobile phone with a web browser. WIB is not the complete server solution – it lacks some features like server side scripting and encryption, for example, althought for most applications, this won’t be a problem. Its main advantage is that it is considerably simpler, cheaper and easier 26  Silicon Chip to set-up than a more powerful web server. In fact, if you have already gone through the set-up procedure for connecting a broadband modem to your computer, this project should not be any more challenging. Remote monitoring In most basic applications, WIB lets you monitor up to four analog inputs and control up to four digital outputs, as well as an RS-232 serial port. WIB not only features an inbuilt web server but includes inbuilt FTP and an email (SMTP) client as well. We will explain these terms as we go through. The email client is used by the WIB to send emails to a nominated email address via an email server. Most ISPs (Internet Service Providers) provide an outgoing email server that the WIB can connect to, in order to send email. The FTP (file transfer protocol) serv­ er allows you to store and retrieve files from a remote location and also allows you to manage your website remotely. In addition, you can use it to back-up files off-site or transfer files (both text and images) to a remote location (eg, from the office to home). The memory card can actually be an MMC, SD or SDHC card (up to 32GB). The website can include dynamic content that’s constantly updated with data from the four analog inputs and WIB can perform data logging of the inputs (as in a weather station) and save this information to a file. The logged data can then be accessed either via the inbuilt FTP (file transfer protocol) server or it can be automatically emailed to you at regular intervals. Just think – you will get emails from WIB – mind-boggling! The emails will be sent from the SMTP ( Simple Mail Transfer Protocol) client within the WIB. In practice, you can set the logging period (ie, how frequently the values are logged) and how many entries to keep in the log file. When this number is exceeded, the log file is automatically emailed to you and then cleared, ready for the next cycle. In this way, you could have daily reports of fluctuations in temperature or whatever emailed to your inbox. The WIB also allows a limit to be set on a variable being monitored and can notify you via email when the variable exceeds this limit. For example, you can set it to email you if the temperature rises above a preset level, so that you immediately know there is a problem. Digital outputs As stated earlier, you can also control four digital outputs and the serial RS-232 port using your browser (eg, Internet Explorer, Mozilla Firefox, Opera, Safari, Google Chrome, etc). These outputs can then be used to control external devices, either directly or via an interface board. It’s just a matter of toggling the digital outputs high or low by clicking on the “Toggle” buttons – see Fig.1. Network time Another feature of WIB is an SNTP (Simple Network Time Protocol) client, which allows the correct time to be gathered automatically from the Internet. This time is used for logging purposes and can also be displayed in a dynamic web page. A dynamic DNS (Domain Name System) client is also included. Domain Name refers to any website name (such as siliconchip.com.au). DNS enables the unit to keep track of its public IP (Internet Protocol) address and notify a DDNS (Dynamic Domain Name System) service if this address changes. By using this service, you can log into the web server using a domain name rather than its IP address (an IP address is siliconchip.com.au numerical and all devices connected to the internet, such as your modem, have an IP address). This is necessary as the public IP address can change if your modem is turned off for some time, so you might not always know what it is. • Highly customisable. Most settings including IP address, port numbers and servers can be arbitrarily set. • MMC/SD/SDHC memory card for storage of web pages and other files (FAT/ FAT32 file system). Earlier design • HTTP (web) server with changeable file permissions, dynamic pages, modified CGI commands and HTTP basic authentication. • • • • • SMTP (email) client for automatic email notifications with dynamic content. • • Four digital outputs for controlling devices over the Internet. • • A serial port output that’s controllable via the Internet. This is not the first web server project to be published in SILICON CHIP. An earlier project, the PICAXE Net Server, was published in the October 2006 issue and was based on a common Realtek ethernet controller chip and a PIC microcontroller. It came as a pre-built module and stored its web pages in an onboard EEPROM chip. Because the data was stored in an EEPROM, the website was limited to 64 kilobytes. Even so, it did allow you to monitor several analog inputs remotely using dynamic web pages and had configurable I/O pins, including a PWM (pulse width modulation) output. By contrast, our new design can store much more complex web pages. Another advantage of the new design is that it implements simple file permissions through HTTP (Hypertext Transfer Protocol) authentication. This means that you can set a user name and password to access the whole website or just certain pages. You can also restrict access to certain files, based on the file extensions. The earlier design lacked a method of restricting access to its web pages and so its onboard website was completely open to the public. Finally, the WIB is highly configurable and can be set up to work with almost any ethernet network. Did we mention ethernet? This refers to the ethernet cable and connectors on the back of your modem. Ethernet is a standard which is used to transmit data over a local network (eg, in an office) or to the internet via a modem. We will also be providing the source code for a website so that you can easily modify the web server’s settings if necessary, to suit your requirements. Circuit details Refer now to Fig.2 for the complete circuit details of the WIB. It’s based on a dsPIC33FJ64GP802 microcontroller (IC1) and an ENC28J60 ethernet controller (IC2), both from Microchip. The ethernet controller (IC2) provides the ethernet link, including siliconchip.com.au Main Features FTP (file transfer protocol) server for uploading web site. Dynamic DNS client (DDNS) to allow server to be contacted using a hostname. Network time (SNTP) client to gather Internet time for logging, etc. Four analog inputs. These can be: (a) monitored remotely using a web browser; (b) logged with periodic log files automatically emailed to a chosen email address; (c) assigned set limits, with automatic email notification when limits are exceeded. 12 user defined file extensions, file permissions and file content for the HTTP server. System logging of special events. MAC (Media Access Control) and the 10BaseT PHY (this means it runs at 10Mbits/second). It has 8KB transmit and receive dual port RAM buffers, hardware assisted CRC (Cyclic Redundancy Check – for error checking), automatic retransmit on collision (in case messages “collide”) and programmable packet (blocks of data) filtering. Although Microchip makes microcontrollers with in-built ethernet controllers, these are only available as surface-mount devices (SMDs). We wanted to avoid SMDs as far as possible so we have specified an external controller (IC2) which comes in a conventional DIL package, as does the specified PIC microcontroller (IC1). The only SMD chip used in the whole project is the 8-pin MAC address chip (IC3) which comes in an SOIC package. And while IC2 does include Media Access Control (MAC), we still need IC3 for providing the unique MAC address; more on this below. In operation, the microcontroller (IC1) communicates with the ethernet controller via an SPI (Serial Peripheral Interface) bus. This SPI bus is also shared with the MAC address chip (IC3) and the memory card, which is accessed in SPI mode. SPI communication requires four lines and these are: CS-bar (chip select – active low), SO (serial data output), SI (serial data input) and SCK (serial clock). You can share the bus among multiple devices by having multiple CS-bar lines and ensuring that only one of these lines is active at any one time. In this case, we use three CS-bar lines: one for the ethernet controller (RB8 of IC1), one for the memory card (RB2 of IC1) and one for the MAC address chip (RB6 of IC1). These are all controlled by the SPI master (IC1). MAC address chip The 25AA02E48 MAC address chip is a 256-byte EEPROM with an SPI interface. It’s main feature is that its last six bytes (bytes with addresses 0xFA to 0xFF) contain a unique, licensed MAC (Media Access Control) address. An ethernet device must have a unique MAC address in order to communicate in a network. By using this chip, we are ensuring that the MAC address for the web server is globally unique. These chips are intended for use in designs with small production runs and save on the cost of licensing a range of MAC addresses from the relevant authority (IEEE). Note that it is quite possible to overwrite the pre-programmed MAC November 2009  27 Reading & Writing Data To The Memory Card T O TRANSFER files from a PC to the memory card, you may need a low-cost SD/SDHC/MMC-card reader. The one shown at left is available from Jaycar for less than $10 (Cat No: XC4756), while the unit at right reads all sorts of memory cards and is also address (it is an EEPROM chip after all). However, the chip has a write protect feature that can be enabled on a 64-byte block basis and the last such block, which contains the MAC address, is protected by default. In any case, the current version of the firmware does not write to the EEPROM and only reads from it. Pin 3 (WP-bar) is the write protect pin and this prevents writing to the EEPROM when low. In our case, however, it has been tied high to allow it to be written to if there is a future firmware upgrade. Pin 7 (HLD-bar) is the hold pin and this pauses the SPI interface logic inside IC3 if it is low. This feature is used in SPI bus sharing situations but has been disabled here by tying pin 7 high. Instead, we rely on the firmware in IC1 to provide proper arbitration between the three SPI devices. Ethernet controller The ethernet controller chip (IC2) provides the physical and data link layer of the network. As already mentioned, it is a 10BaseT PHY (physical layer) running at 10Mbits/s and the data is transmitted on twisted-pair copper cables terminated in an RJ45 connector (the ethernet socket). PIC microcontroller IC1 writes to the ethernet controller’s registers via the SPI bus which runs at 8MHz. Ethernet transmissions occur by Manchester encoding on the T+ (pin 17) and T- (pin 16) pins of IC2 via two 51Ω resistors. 28  Silicon Chip available from Jaycar (Cat. XC-4849). They are simply connected to a PC via a USB port. Suitable memory card readers are also available from Altronics. The resistor values are chosen to be close enough to match the characteristic impedance of the 10BaseT (ethernet) cable, which is 100Ω. Similarly, reception occurs on the R+ (pin 13) and R- (pin 12) pins of IC2. The ethernet controller (IC2) requires some passive components to complete the physical ethernet link (ie, to transmit and receive data), including two transformers. These transformers plus, four 75Ω resistors and a 1nF capacitor, are all part of RJ45 connector CON2 and provide electrical isolation from the network. In addition, the RJ45 connector contains two LEDs, one green and the other yellow. According to the datasheet for the ENC28J60 (IC2), a 2.32kΩ resistor from pin 14 (RBIAS) to ground is required to set the signal amplitude on the transmitting pair. This is made up using series 2kΩ and 330Ω resistors to give 2.33kΩ, which is near enough. IC2 also requires a 25MHz crystal to operate correctly and this, together with its two 33pF loading capacitors, is connected to pins 23 & 24. Outputs LEDA and LEDB of IC2 drive the two LEDs in the RJ45 connector. These outputs can be configured (using the registers in IC2) to light the connector LEDs under various conditions. In this case, we have chosen to drive the LEDs to conform to the usual convention, with the green LED indicating a valid ethernet link and the yellow LED indicating data activity. The remaining line to IC2 is the RSTbar line (pin 10). This is the reset line and is driven by the RB7 (pin 16) output of the microcontroller. It simply resets the internal logic of the ethernet controller (IC2) when required. Note that there are two other lines on IC2 which are unused: CKO and INT-bar. CKO (pin 3) is a clock out line and this delivers a square-wave whose frequency is related to IC2’s system clock (in turn derived from the 25MHz crystal). This frequency can be configured via IC2’s registers (it can be used to provide the clock for a microcontroller for example) but is not used here as IC1 has its own crystal (X1). This was done to allow the microcontroller to run at its highest rated clock frequency. The other unused line (pin 4) is the interrupt line. This can be used to interrupt the microcontroller under certain circumstances but again is not used here. Memory card As mentioned above, the memory card is accessed in SPI mode and this is done via the SD card socket (CON4). This allows microcontroller IC1 to read from and write to the memory card. MMC/SD/SDHC cards can be accessed either in native mode or in SPI mode. The advantage of the SPI mode is that any off-the-shelf microcontroller that has an SPI peripheral can be used, making the hardware layer easy to implement. The interface with SPI is also simpler but the penalty is slower transfer speeds. However, SPI speeds are quite adequate for serving web pages. Inputs & outputs Connector CON3 provides access to the analog inputs and the digital outputs. The four analog inputs are AN0-AN3 of IC1 (pins 2-5) and these inputs are all protected using 10kΩ current-limiting resistors. An AD22103 temperature sensor IC (IC4) is shown connected to AN0 on Fig.2 but other types of sensors with a linear 0-3.3V output (or less) can also be used on the analog inputs. The digital outputs are at RB12RB15 (pins 23-26) of IC1 and toggle between 0V and 3.3V. CON5 allows optional access to the serial (UART) port of IC1. Note that siliconchip.com.au siliconchip.com.au November 2009  29 A SC 2009 CON5 13 Tx Rx Vr R1: 110Ω GND 33pF 4 x 10k Vdd (+3.3V) 110Ω R3:0Ω R2: 180Ω OUT ADJ +V IN REG1 LM317T 33pF X1 8MHz 10 µF 1 10 9 11 28 8 19 Vss Vss AVss 27 RB2 RB6 OSC2 OSC1 RB4 RB5 330Ω +3.3V 6 15 12 RA4 7 RB3 16 RB7 17 RB8 22 RB11 21 RB10 18 RB9 IC1 dsPIC33 FJ64GP 802 Vcap 2 AN0 3 AN1 4 AN2 5 AN3 14 13 MCLR Vdd AVdd RB12 24 RB13 25 RB14 26 RB15 23 20 470 µF 1k WIB: WEB SERVER IN A BOX TEMPERATURE SENSOR (OPTIONAL) 3 GND 1 CON3 33 µF K D1 1N4004 IC4 2 Vo AD22103 1 Vs CON1 +6-9V DC INPUT K K λ LED2 A 330Ω 10 µF 2.0k λ LED1 A 330Ω OSC1 SO 8 Vcc 1 CS SI Vss 4 23 24 27 26 HLD 3 A K 1N4004 WP 7 +3.3V Vss 2,11,18 21,22 Vcap IC3 25AA02 6 SCK E48 5 2 1 13 T+ 17 16 T– R– 12 CKO 4 INT 5 NC 10 R+ RST 9 IC2 CS 6 ENC28J60 SO 7 SI LEDB 8 SCK LEDA 14 Rbias OSC2 3 Vdd 15,19,20, 25,28 100nF 33pF X2 25MHz 7 9 51Ω 8 10 4 6 5 3 1 K λ RJL2 A K λ RJL1 A Vo Vs AD22103 K A (RJ45) 1nF 4x75Ω 3 4 5 6 7 8 1 2 LEDS ADJ OUT LM317T IN 6 3 1 5 2 7 4 OUT CON4 Vss2 Vss1 CS CK DI DO Vdd SD CARD SOCKET (AMPHENOL RJMG163218101NR) RECEIVE LED1: DISK ACCESS LED2: BLINKING = NORMAL OPERATION 100nF 51Ω 51Ω GND 33pF 2 x 330Ω 100nF 51Ω 2 CON2: RJmag CONNECTOR MODULE TRANSMIT Fig.2: the circuit is based on a PIC microcontroller (IC1), an ENC28J60 ethernet controller (IC2), a 25AA02E40 MAC address chip (IC3) and an external memory card. The PIC microcontroller interfaces to the memory card, reads the analog inputs and controls the digital outputs at RB12-RB15. It also drives the ethernet controller (IC2) which in turn interfaces to the external network via an RJ45 connector. IC4 is an optional temperature sensor (AD22103) and is connected to one of the analog inputs (AN0 in this case). Power comes from a 6-12V DC regulated plugpack supply. – + All The Jargon Explained DNS (Domain Name System): a system whereby domain names can be resolved to IP addresses. DDNS (Dynamic Domain Name System): a system whereby a fixed domain name can be associated with a dynamic IP address. DHCP (Dynamic Host Configuration Protocol): a protocol that allows a DHCP server to assign an IP address to a DHCP client requesting it. The IP address is handed out on a limited time lease. EEPROM (Electrically Erasable Programmable Read-Only Memory): a solid-state nonvolatile memory chip that can be written to and erased. Ethernet: a network standard for the physical and data link layer that determines how data is transmitted and received from a common medium. FTP (File Transfer Protocol): a protocol used to transfer files across a network. Gateway: a network node to which data traffic is directed. It relays this traffic in a way so as to reach its destination (using routing information). HTTP (Hypertext Transfer Protocol): a protocol commonly used to transfer web pages and content from a web server to a browser. ICMP (Internet Control Message Protocol): a protocol used to send status and error messages across the Internet. It is typically used for Ping (Packet Internet Groper). IP (Internet Protocol): a protocol used for transmitting data packets across a network, primarily used in the Internet. IP Address: each device sending or receiving IP packets must have a unique IP address, typically written as four decimal numbers in the range 0-255 (8-bit) and separated by dots. An example IP address is 192.168.0.34. MAC (Media Access Control): a protocol that implements the data link layer on an ethernet network where nodes share a common medium. MAC Address: each device sending or receiving ethernet packets must have a unique MAC address. This is is a 6-byte address which is often written as six hexadecimal bytes joined by colons, for example: 00:04:A3:21:09:6C. Manchester encoding: a self-clocking method of encoding binary data that relies on edge transistions. Multi-tasking: the ability of a processor to run multiple tasks. NAT (Network Address Translation): a technique whereby a router can modify address and port information in packets to translate from one address space to another. Typically used in routers to share a single connection from your ISP among many devices in a home network. Port Forwarding: a technique used by routers to redirect traffic on a particular TCP or UDP port to a private IP address. Protocol: a set of rules to allow network devices to communicate with each other. SMTP (Simple Mail Transfer Protocol): a protocol used for sending email. SNTP (Simple Network Time Protocol): a protocol used to receive time information from a remote time server. The time is returned as a number that represents the number of seconds that have elapsed since the epoch time which is set at 00:00 1 January 1970. Static DHCP: a technique whereby a DHCP server can be made to assign a static IP address to a particular network device (by associating a static IP address with a MAC address). Subnet Mask: this is in the style of an IP address and is used as a bitwise AND mask to determine whether an IP address is in the same network subnet. TCP (Transmission Control Protocol): a protocol for transmission of data that is connection oriented. TCP/IP (Transmission Control Protocol/Internet Protocol): a family of protocols that allow network devices to communicate. UART (Universal Asynchronous Receiver/Transmitter): a circuit used for serial commun­ ication between devices. UDP (User Datagram Protocol): a protocol for transmission of data that is packet oriented. 30  Silicon Chip the levels are not true RS232 levels but simply 3.3V CMOS levels. LED indicators Outputs RA4 and RB3 from IC1 are used to drive indicator LEDs1 & 2. LED1 (green) lights when ever the memory card is accessed (ie, for both reads and writes), while LED2 (orange) is on during boot up until all initialis­ ations have been completed. Once the web server has initialised, LED2 blinks on and off to indicate normal operation. When LED2 is blinking, it shows that the cooperative multitasking main loop is executing, ie, no process is blocking operation or taking up inordinate processor time. At no time should the orange LED stop blinking during normal operation, otherwise data packets will be dropped. Clock signals Clock signals for the microcontroller are derived from an 8MHz crystal (X1). This is connected between pins 9 & 10 (OSC1 & OSC2), together with two 33pF capacitors which provide the correct loading. Note that IC1 runs at its maximum of 40MIPS (millions instructions per second) – an internal PLL (phase lock loop) stage is used to derive the system clock. Power for the CPU inside IC1 is derived from the main 3.3V rail using an internal 2.5V regulator. This requires a 10µF tantalum bypass capacitor on pin 20. Similarly, a 10µF bypass capacitor is fitted to pin 1 of the ethernet controller (IC2). Note that IC1’s reset pin (MCLR-bar, pin 1) is pulled permanently high by a 1kΩ resistor and so is not used here. Instead, IC1 is reset by its internal power-on reset logic. Power supply Power for the circuit is derived from a 6-9V DC plugpack and this is applied via reverse polarity protection diode D1. The resulting DC rail is then filtered using a 33µF capacitor and fed to an LM317T adjustable 3-terminal regulator (REG1) to derive a +3.3V rail. This +3.3V rail then powers ICs1-3 and the memory card. REG1’s output voltage is set by the divider network on its OUT & ADJ terminals according to the following formula: VOUT = 1.25V x (1 + (R2/R1)) By using a 110Ω resistor for R1 and a siliconchip.com.au 180Ω resistor for R2, we get an output voltage that’s very close to 3.3V. In practice though, the 1.25V reference in the regulator can vary anywhere between 1.2V and 1.3V, due to manufacturing tolerances. For this reason, provision is made on the PC board for an additional resistor (R3) in series with R2 so that you can adjust the output voltage if necessary. In most cases, you won’t need to do this and a wire link is used for R3 instead (more on this later). The supply rail at the output of diode D1 is also fed to a terminal on CON1, so that it can be used to power external devices if necessary. In addition, the +3.3V rail is fed to two other terminals on CON3, in one case via a 110Ω current-limiting resistor. The current-limited +3.3V rail (Vr) is used to power the AD22103 temperature sensor (IC4). The 110Ω current-limiting resistor is necessary because the temperature sensor is connected to the circuit via a stereo jack socket. In operation, it prevents the supply rail from being shorted to ground each time the stereo jack is plugged into its socket (the jack’s tip touches the socket’s ring as it is inserted). The 110Ω resistor protects against short circuits and doesn’t interfere with the operation of the temperature sensor itself, as the latter’s current draw is negligible. Ethernet Web Server Parts List 1 PC board, code 07111091, 123 x 74mm 2 28-pin 0.3-inch IC sockets 1 3-way pin socket, 2.54mm pitch 8 M3 x 6mm machine screws 4 M3 x 15mm tapped Nylon spacers 1 250mm-length of 0.7mm tinned copper for links 1 2.5mm PC-mount male DC power connector (Jaycar PS0520, Altronics P-0621A) 1 TO-220 mini heatsink (Jaycar HH-8502, Altronics H-0630) 1 8MHz crystal (X1) 1 25MHz crystal (X2) 1 plastic instrument case, 95 x 158 x 47mm (Jaycar HB-5922) 1 SD surface-mount memory card socket (Altronics P5722) 1 ethernet RJ45 Connector with Magnetics, Amphenol RJMG163218101NR (Farnell 135-7435) 3 3-way screw terminal blocks (5.04mm pitch) 2 2-way screw terminal blocks (5.04mm pitch) 1 6-9V DC 300mA plugpack (Jaycar MP-3145 or Altronics M-9208 plus M-9191 connector) 1 3.5mm stereo jack (optional) 1 3.5mm stereo socket, chassis mount (optional) Semiconductors 1 dsPIC33FJ64GP802-I/SP programmed with 0711109A.hex (IC1) 1 ENC28J60 ethernet controller (IC2) 1 25AA02E48 serial EEPROM with MAC address (IC3) 1 AD22103 temperature sensor (IC4) (optional) (Farnell 1438415) 1 1N4004 silicon diode (D1) 1 LM317T adjustable 3-terminal regulator (REG1) 1 3mm green LED (LED1) 1 3mm orange LED (LED2) Capacitors 1 470µF 16V electrolytic 1 33µF 16V electrolytic 2 10µF tantalum 3 100nF monolithic 4 33pF ceramic Resistors (0.25W, 1%) 4 10kΩ 1 180Ω 1 2kΩ 2 110Ω 1 1kΩ 4 51Ω 5 330Ω Firmware overview OK, so that’s the hardware side of things and it’s all fairly straightforward. Most of the features are implemented in the firmware, so let’s now take a closer look at this. The firmware uses the freely available TCP/IP stack from Microchip. We’ve customised it and also implemented some missing features in the minimal stack. The stack is based on a cooperative multi-tasking model (ie, a lot of tasks run concurrently) and this has been retained. The main program is an infinite loop, with finite state machines used to keep track of stack processes that need attention. The other major addition is the memory card driver and the FAT/ FAT32 file system that resides on top of that. The WIB recognises the FAT/ FAT32 file system which means that you should be able to read the memory card using any Windows, Mac or Linux box (and a card reader). siliconchip.com.au The modules used in the TCP/IP stack include HTTP, FTP, ICMP, SNTP, SMTP, DNS and Dynamic DNS. Only the limited amount of program memory on the microcontroller prevented us from including further modules such as a DHCP client to automatically pick up an IP address. Because there’s no DHCP client, the web server is assigned a static IP address and this is also necessary for port forwarding. However, a DHCP client working in conjunction with static DHCP could have been useful for incorporating the web server into an automatically configured network. In any case, the DHCP server in your router must be configured to reserve a static IP address for the WIB. We’ll tell you how to do that next month. MMC/SD/SDHC memory cards Either an MMC, SD or SDHC memory card can be used in the web server. MMC (MultiMedia Card) and SD (Secure Digital) cards use FLASH memory technology and are available in capacities up to 2GB. SDHC cards are essentially high-capacity SD cards and are available in sizes ranging from 4GB to 32GB. All three types of card can be used in this project. Note that while all three types look alike, MMC cards have only seven metal contacts whereas SD cards have nine. MiniSD and MicroSD cards can also be used. These are essentially SD cards but are smaller. You will need an external adaptor in order to plug them into the SD card socket used in the web server. Construction Building the WIB is easy with all parts mounted on a single-sided PC board coded 07111091. This board measures 123 x 74mm and is housed inside a plastic utility case. The only slightly tricky bit is the surNovember 2009  31 Fig.3: install the parts on the PC board as shown on this layout diagram. Make sure all polarised parts are correctly oriented and leave IC1 & IC2 out until after the power supply has been checked – see text. CON2 CON1 RJMG1632 18101NR 1 2 3 4 5 6 33F 180 0 D1 7 REG1 LM317T 8 10 9 + 110 330 470F + R19 GND 100nF 100nF X2 100nF Fig.4 (below): this diagram and the accompanying photos show how IC3 and the SD memory card socket are installed on the track side of the PC board. Note the orientation of the IC and don’t forget to solder the two tabs of the memory card socket adjacent to the edge of the board. 2.0k + IC3 (UNDER) 10F 10F + IC3 IC1 dsPIC 33FJ64GP802 X1 10k 10k 33pF CON5 LED1 33pF NOTE: IF PC BOARD HAS NO SOLDER MASK LAYER, PLACE A 23 x 16mm PIECE OF INSULATING SHEET UNDER CON4 TO PREVENT ITS SHIELD PLATE SHORTING COPPER TRACKS. 10k 10118 7 1011 10k CON4 LED2 330 ANALOG INPUTS Vss (GND) Vdd (3.3V) 51 IC2 ENC28J60 1k DIGITAL I/O +3.3V 51 51 330 CON3 51 330 +DC IN 330 33pF 33pF 6 5 4 3 2 1 9 CON4 07111091 MMC/SD/SDHC ETH WEB SERVER CARD SOCKET MG 07/09 29011170CARD MMC/SD/SDHC REVRES(UNDER) BEW HTE SOCKET 90/70 GM UNDERSIDE VIEW SHOWING SMD COMPONENTS face-mount IC (IC3) which is mounted on the copper side of the PC board. However, this SOIC device has only eight pins and the pin spacing is around 1.27mm, so it’s not difficult to hand solder. Figs.3 & 4 show the parts layout on the PC board. However, before beginning the assembly, it’s a good idea to carefully inspect the board for etching defects (eg, shorted tracks and hairline cracks). Such faults are rare but checking now can save a lot a hassle later on. Check also that corner cutouts have been made at the CON1 & CON2 end of the board, so that it will later clear the mounting posts inside the case. If not, you will have to make the cutouts yourself using a fine-toothed hacksaw and a small, flat file. Having done that, the first job is to install the 11 wire links – see Fig.3. These can be cut from a length of 0.7mm tinned copper wire. If necessary, you can first straighten the link wire by clamping one end in a vise and 32  Silicon Chip then stretching it slightly by pulling on the other end using a pair of pliers. Once the links are in, the next step is to install the resistors. These can go in either way and some are mounted end-on to save board space. Table 1 shows the resistor colour codes but you should also check each one with a DMM before installing it. You can either use a zero-ohm resistor for R3 or you can install a wire link. Diode D1 and crystals X1 & X2 are next on the list. Note the orientation of D1 and don’t get the two crystals mixed up. The 8MHz crystal is used for X1, while the 25MHz crystal is X2. Now for the LM317T regulator (REG1). This mounts horizontally on the board and is fitted with a mini heatsink for cooling. It’s installed by first bending its leads down by 90° about 5mm from its body. It’s then secured in place, along with its heatsink, using an M3 x 6mm machine screw, flat washer and nut and its leads soldered. Note: do not solder REG1’s leads before bolting it down. If you do, the PC tracks could crack as the assembly is tightened down. The two 28-pin machine IC sockets can now be installed. Be sure to orientate these with their notched ends as shown on Fig.3. If you are unable to obtain 28-pin 0.3-inch sockets, you can use pin header strips instead. Alternatively you can cut 28-pin 0.6inch sockets in half or you can use two 14-pin sockets mounted end-to-end. Do not install the two ICs in their sockets yet. That step comes later. Follow these parts with the capacitors, starting with the 33pF ceramic and 100nF monolithic types. The two 10µF tantalum capacitors can then be installed, followed by the 33µF and 470µF electrolytics. Note that the tantalum and electrolytic capacitors are all polarised, so make sure they go in the right way around – see Fig.3. Connectors The DC socket (CON1), the RJ45 siliconchip.com.au make sure they are oriented correctly. A 25mm-high cardboard spacer can be used to set their height. Just slide this spacer between each LED’s leads and push the LED down onto it before soldering it in place. Initial tests You will need a 6-9V DC 300mA (or greater) regulated plugpack fitted with a 2.5mm connector to power this project. Suitable plugpacks include the Jaycar MP-3145 and the Altronics M-9208. Note, however, that the latter requires swapping the supplied 2.1mm connector for a 2.5mm connector (Altronics M-9191). With the three ICs out of the circuit, apply power and use a DMM to measure the voltage between the OUT terminal of REG1 and GND. It should measure close to 3.3V and this same voltage should also appear at the Vdd (3.3V) terminal of CON3. If you don’t get the correct reading, switch off immediately and check for wiring errors. In particular, check the resistor values on the OUT and ADJ terminals of REG1 if the reading is high or low. Alternatively, if you don’t get any voltage at all, check the supply polarity and D1’s orientation. This view shows the completed PC board. Note that there are a few differences between this prototype board and the final version shown in Fig.3, especially around CON1, CON2 and REG1. connector (CON2) and the 3-way pin socket (CON5) can now go in. Make sure that these parts are sitting flush against the PC board before soldering their pins. In addition, take care when soldering the RJ45 connector as some of its pins are quite close together and it’s easy to get solder shorts. Don’t forget to solder the two pins near the edge of the PC board, as these help secure the socket in position. The 13-way screw terminal block (CON3) is made up using three 3-way Trimming the 3.3V rail The accuracy of the +3.3V rail is important because some MMC/SD/ SDHC cards operate over quite a narrow voltage range. The firmware checks that the inserted card operates at 3.3V and so it is crucial that REG1’s output be close to +3.3V. If the 3.3V rail is more than 3.4V or less than 3.2V, you will need to change one or both of the values for R2 and R3. For example, if the voltage is around +3.17V, you will need to install a 10Ω resistor for R3 and this should increase the rail so that it is close to +3.3V. Alternatively, if the output voltage is +3.41V, you should change the value blocks and two 2-way blocks. These should all be dovetailed together and mounted as a single unit, with the access holes facing the edge of the board. The board assembly (minus the three ICs and the SD card socket) can now be completed by soldering in the two LEDs. These should both be mounted at full lead length, with their bodies 25mm above the board so that they will later protrude through the lid of the case. Use the green LED for LED1 and the orange LED for LED2 and Table 1: Resistor Colour Codes o o o o o o o siliconchip.com.au No.   4   1   4   1   2   4 Value 10kΩ 1kΩ 330Ω 180Ω 110Ω 51Ω 4-Band Code (1%) brown black orange brown brown black red brown orange orange brown brown brown grey brown brown brown brown brown brown green brown black brown 5-Band Code (1%) brown black black red brown brown black black brown brown orange orange black black brown brown grey black black brown brown brown black black brown green brown black gold brown November 2009  33 69 (TOP OF CASE) A A 5 45 95 108 26 158 15.75 A A (BOTTOM OF CASE) 32 HOLES 'A' ARE 3mm DIAMETER 63.5 103.5 22.5 A A ALL DIMENSIONS IN MILLIMETRES 15.75 Fig.5: here are the drilling details for the top and bottom case sections. All the holes are drilled to 3mm diameter. of R2 to 160Ω and R3 to 10Ω (giving a total value for R2 + R3 = 170Ω), or you could use 150Ω for R2 and 22Ω for R3. Again, this should bring the voltage from REG1 pretty close to +3.3V. Once the supply voltage is correct, switch off and install IC1 & IC2 into 34  Silicon Chip their sockets. Make sure they are oriented correctly (see Fig.3) and don’t get them mixed up. Installing the SMD parts The SMD parts (ie, IC3 and SD card socket CON4) mount on the copper side of the board as shown in Fig.4. You will need a fine-tipped soldering iron, some fine solder, some solder wick and (preferably) a magnifying lamp. Begin by carefully aligning the IC with it solder pads, making sure that siliconchip.com.au The PC board fits neatly inside a standard plastic utility case (note: the final board is longer than the version shown here). The memory card can be removed or installed by sliding the adjacent end panel out of its slot. it is oriented as shown (ie, pin 1 at upper right, as indicated by the dot in its body). If you like, you can hold it in position using self-closing tweezers. That done, lightly tack solder pin 1, then remove the tweezers and inspect the IC under a magnifying glass to make sure it is in the correct position. The remaining pins can then be soldered, starting with the diagonally opposite pin (pin 5). Don’t forget to add a little more solder to pin 1 if necessary to complete the job. Do this job quickly, so as not to overheat and damage the tracks on the PC board. Once you have finished, inspect the job under a magnifying glass again. If any of the pins are shorted by solder (other than pins 7 & 8), then you can remove the excess solder using the solder wick. Memory card socket While you are on the copper side of the PC board, you can solder in the memory card socket as well. It is an SMD socket so you must place it over its pads and solder in one of the pins first to anchor it in position. Once that is done, check that it is correctly aligned before soldering the remaining pins. Note that there are two mounting siliconchip.com.au RJ45 CUTOUT 11 16 41 16 DC INPUT CUTOUT 14 12 10 18 17.5 (RIGHTHAND END PANEL) 88 Fig.6: here’s how to make the cutouts in the righthand end panel for the RJ45 socket and the DC power socket. M3 x 6mm SCREWS PC BOARD M3 x 15mm NYLON SPACERS BOTTOM OF CASE M3 x 6mm SCREWS Fig.7: the PC board is mounted in the case on four M3 x 15mm tapped Nylon spacers and secured using M3 x 6mm screws. pads towards the front of the socket that also have to be soldered. Final assembly The prototype was housed in a plastic instrument case measuring 95 x 158 x 47mm (Jaycar HB-5922). This is marked out and drilled as shown in Figs.5 & 6. As shown, you need to drill two 3mm holes in the lid for the LEDs and four 3mm mounting holes in the base (Fig.5). In addition, you have November 2009  35 Installing The Temperature Sensor The optional AD22103 ratiometric temperature sensor (IC4) is installed by mounting it inside a 3.5mm stereo plug – see Fig.8. Its +Vs lead is connected to the ring terminal of the stereo plug, its Vo lead to the sleeve and its GND lead to the tip. This then plugs into a matching stereo jack socket mounted on the end of the case and this is wired back to CON3 on the PC board. As shown in Fig.8, the +Vs supply lead connects to the +Vr terminal (terminal 2) of CON3, the GND lead connects to terminal 7 of CON3, and the Vo (sensor voltage output) lead connects to one of the four analog inputs of CON3 (either terminal 9, 10, 11 or 12). The temperature sensor is mounted outside the case to ensure that it is unaffected by the heat generated by other The AD22103 temperature sensor is mounted inside a 3.5mm stereo jack – see Fig.8. to make two square cut-outs in one of the end panels for the DC socket and RJ45 connector (Fig.6). Each of these cut-outs can be made by drilling a series of small holes GND TO PIN 7 OR 13 OF CON3 +Vs TO PIN 2 OF CON3 Vo TO PIN 9, 10, 11 OR 12 OF CON3 HIS SERVER relies on a username and password for security. This username and password combination must be used to access the FTP server (to modify the file system) and to access private web pages through HTTP (ie, using a web browser). This is the main security mechanism to prevent unauthorised access from a remote location over the Internet. All settings should also be protected by the username/password combination and this is the approach taken in the sample website we are providing for download from the SILICON CHIP website. 36  Silicon Chip RING SLEEVE 3.5mm STEREO PLUG END OF CASE +Vs TO RING TEMP SENSOR PLUGS IN HERE AD22103 TEMP SENSOR (FLAT SIDE) GND TO TIP Vo CONNECTED TO SLEEVE PLUG COVER Fig.8: connect the AD22103 temperature sensor to the 3.5mm stereo plug as shown here. You can use a DMM to identify the tip and ring terminals. parts. This heat comes mainly from the LM317T voltage regulator but the ICs also contribute. Mounting the sensor outside the case ensures an accurate measurement of the room temperature. around the inside perimeter, then knocking out the centre piece and cleaning up the edges with a flat file. If you are installing the specified temperature sensor, then you will also need to drill a 6mm hole in the second end panel (see Fig.8 and photos). Deburr all holes using an oversize drill, then secure four M3 x 15mm Nylon spacers to the base using M3 x 6mm screws. The PC board can then be dropped into place along with the righthand end panel and secured using another four M3 x 6mm screws as shown in Fig.7. Installing the memory card You will need a suitable MMC, SD or SDHC memory card to use with the Security Disclaimer T 3.5mm STEREO JACK SOCKET TIP Note, however, that given the correct username and password combination, a user could log into the server and change all the settings by accessing the file system on the memory card through an FTP client. In addition, they could change the password and username combination to lock others out of the system. If that ever happens, the remedy is to write to the card using a PC and a memory card reader and define a new username/password pair. Of course, this assumes you have physical access to the memory card. This web server cannot be WIB. This should be formatted with a FAT/FAT32 file system before plugging it into the memory card socket (see photo). With the ICs installed and power applied, the orange LED should blink on and off approximately twice a second. That completes the construction of the WIB. However, before using the device, you need to copy the necessary files to the memory card and interface the server to your network. This will involve entering a few settings like the Gateway address, IP Address and Subnet mask, turning on port forwarding in your router and activating a dynamic DNS (DDNS) service. We’ll explain how that’s all done in SC Pt.2 in next month’s issue. considered highly secure because it is prone to DoS (denial of service) attacks, as are most web servers. On a positive note, HTTP authentication occurs server side and therefore no transmission of a coded version of the username and password occurs (although it is possible to intercept the HTTP headers that contain the correct username and password – they are not encrypted but encoded using base64). There are also a limited number of commands, no server side script execution and the microcontroller uses a (modified) Harvard architecture, making the server somewhat more secure than most. siliconchip.com.au