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Part 2 of our quality Weather Station based on System designed by Armindo Caneira* Built and written by Trevor Robinson *www.meteocercal.info Starting to build it: the ‘TX’ board L ast month, we told you how we obtained many of the specialised parts from ebay sellers – in fact, quite a number came from just a couple of them. If you’re considering building your own weather station, we’ll assume you’re well on the way to obtaining these parts, along with the PCBs which come from the designer in Portugal (www.meteocercal.info). In this second instalment, we list all the parts, conveniently broken down into individual lists for each component (ie, the transmitter, receiver etc) and then we move on to building the first module – the TX (transmit) Unit. As you can see, apart from the specialised parts, most are “garden variety” components available at virtually any electronics retailer. We understand that some of these retailers may also attempt to obtain stock of the more specialised components as well. Building the TX unit If you’re familiar with building projects you can skip this part as it’s all common practice and common sense. If not, though, there are a few tips to keep in mind: The soldering iron Keep your soldering iron tip clean. Use a wet sponge (often incorporated into soldering iron stands) or a copper or brass woolly pad to regularly drag the tip over. If you’re not using the iron, turn it off – nothing kills a 72  Silicon Chip soldering iron tip faster than leaving it heated. And if you don’t already have one, a temperature-controlled soldering station is a really good investment (particularly if you build more projects, repair devices and so on). Beware of static Quite a few of the components in this project can be damaged by static electricity. This can build up on you and on your tools (including the soldering iron) simply by using them – and usually you don’t know about it! If a component is supplied to you on foam, in foil or in an anti-static tube, take anti-static precautions such as earthing the workspace and yourself, making sure any tools you use are discharged and so on. It also pays to leave the component in the anti-static material until you are ready to use it. You’ll find a lot of helpful tips on the internet, courtesy of Dr Google. Populating the PCB These are double-sided boards so the first thing to do is work out which is the “normal” (or top) component side and which is the reverse side. Use our component overlay diagrams for this. It’s normal practice to insert the lowest height components first – obviously, resistors fall into this category. Capacitors are usually soldered in next, remembering siliconchip.com.au that electrolytic types are polarised and must be inserted into the PCB so that the “-” on the side of the component matches the “-” symbol on the PCB. Leave diodes and other semiconductors until later, with “hardware” the last to go on. Soldering When soldering the components in, make sure you don’t use too much heat but you need enough heat to make sure the component leads are properly soldered to the pads on both sides of the board, where appropriate. If soldering a heat-sensitive component such as a transistor, it’s better to leave as much leg length as possible because this will tend to minimise the heat getting to the transistor itself. You can also use a small clip-on heatsink (or even a crocodile clip) on each lead as you solder to further protect the device. Also make sure you don’t use too much solder and form bridges between pads – most particularly when pads are very close together. Good soldering comes with practice, practice and more practice. Inspection When complete, give your PCB the once-over – twice! First check your component placement, including polari- ties where required, against the overlay diagram. If there are any blank component positions, check that they are supposed to be – blank, that is! If you’re happy with what you’ve done, then use a loupe or magnifying glass to carefully inspect the soldering. Where possible, check both top and bottom The miniature 433MHz joints and if in doubt, use a con- transmitter module solders into the TX PCB. tinuity tester (or a multimeter) to check for shorts between pins or pads. If a joint looks doubtful now, re-solder it and avoid problems later! Notes about the PCB and components Normally, you won’t need to install resistors labelled R5 and R6 (10kΩ, 0.25W) on the PCB, as they are for optional I2C devices that don’t have internal pull-up resistors. After installing the 20kΩ preset potentiometer, set it to its mid-point (ie, 10kΩ). This is a fine adjustment for the wind vane but once set to 10kΩ, it’s unlikely to need further adjustment. The 7809 regulator and the IRLZ44N MOSFET both come in “TO-220” packages so are easy to mix up. Refer to SCL OUT +BAT 2 IN 12V 1 GND 100nF 4 3 REG1 7809 +9V 100nF GND POWER 3 SDA 2 +5V 1 1 GND 3.0k 2 2 IC A0 A1 SDA SCL GND +5V 3 1 4 2 5 3 6 4 7 5 8 6 9 10 UV-SOL 4.7k 4.7k 11 12 +5V 13 14 15 V+ OUT IC1 TMP36 D12 D11 3.3V D10 A0 D9 A1 D8 A2 D7 A3 D6 ARDUINO NANO A4 A5 D5 D4 A6 D3 A7 D2 5V GND 30 5 29 4 28 3 27 2 26 1 25 D10 +5V GND EXP 24 3 23 DATA 2 22 20 100nF  19 LED2 FAN K +9V 1 K A 21 GND RF_TX D1 1N4004 A 1 18 +9V 2 17 GND D12 D11 D 100 –V FAN 16 Vin G VR1 20k GND 10k 10k S Q2 IRLZ44N 1 TEMPERATURE SENSOR 2 +5V 2N7000 LM35DZ 3 4 GND V+ D OUT G D D IN S S K K D S G 10k 100nF 4 3 2 1 100nF RAIN CLK 4 3 2 1 WIND K A ARDUINO WEATHER STATION TX MODULE siliconchip.com.au DAT +5V DHT22 390 LEDS OUT 1N4004  Q1 2N7000 GND GND A A TX LED1 1k 7809 IRLZ44N G +9V GND Fig.1: the circuit diagram for the first WeatherDuino module to be built, the TX (Transmitter) Module. April 2015  73 Parts List – TX Unit Parts List – RX Unit 1 WeatherDuino Pro2 TX V4.0 PCB       (Notes) 1 Arduino Nano v3.0 microprocessor module (H) 1 SHT10 digital temperature and humidity sensor module 1 FS100A 433MHz TX module (I) 1 433MHz antenna (D) 1 SMA female panel connector, with pigtail (C) 1 TMP36 temperature sensor (#) (G) 1 case to suit (E) 1 heatsink to suit 7809 (#) 1 12V DC fan (optional – used only with a Stevenson Screen) 1 power supply, 12VDC <at> 1A or higher if fan used Connectors (both plug and socket required #) 1 3-pin polarised header (power & battery voltage sensing) 1 2-pin polarised header (“Stevenson Screen” fan) 2 4-pin RJ-12 4P4C sockets (for temperature sensors) 1 6-pin polarised header (UV solar interface) 1 5-pin header (for expansion port; optional – unused but may be used for later expansion) Semiconductors 1 IRLZ44N N-channel MOSFET (Q2) 1 2N7000 N-channel MOSFET (Q1) 1 7809 9V positive voltage regulator (REG1) 1 1N4004 rectifier diode (D1) 1 3mm red LED (LED1) 1 3mm green LED (LED2) (G) Capacitors 1 100nF ceramic Resistors (0.25W, 5% or better) 3 10kΩ 2 4.7kΩ (J) 1 3kΩ 1 1kΩ 1 20kΩ horizontal trimpot 1 390Ω 1 100Ω (#) – See text for more information their labels and the screen printing on the PCB to get them correct! In both cases, the metal heatsink of both of these devices goes towards the edge of the PCB. To connect the SMA pigtail GND, you have to carefully remove some of green solder-mask on the FS1000A module’s PCB, near the ANT hole. Then solder the centre conductor to the “ANT” and the shielding braid to the 4004 Most constructors will power the TX unit with a 12V DC IC1 LM35 100nF 100nF 10k 4.7k 4.7k GND Vin A7 5V 3.0k UV–SOL WIND 1k 390 DAT 5V CLK GND SCL GND 5V A0 A1 SDA 12V D1 100 SDA 5V GND Power connection VR1 20k 100nF D3 D2 GND D7 D6 D5 D4 A0 A1 A2 A3 A4 A5 A6 REG1 7809 10k WeatherDuino Pro2 TX v2.50 By Werk_AG www.meteocercal.info SCL where you removed the varnish. When installing the Arduino Nano, stagger the soldering of the pins to avoid heat build-up. Even better, use a 30-pin socket and plug the Nano in later. GND Q2 IRLZ44N +Bat 10k GND Q1 2N7000 Arduino Nano 3.3V Resistors (0.25W, 5% or better) 2 10kΩ 1 360Ω 1 120Ω (use 100nF ceramic capacitor instead if your Arduino Nano has a CH340 chipset) POWER 100nF D12 D11 D10 D9 D8 EXP Data Vcc RF_TX SHT21/I2C Connectors (both plug and socket required #) 1 3-pin polarised header (power & battery voltage sensing) 1 2-pin header (for screen mode pushbutton switch) 1 2-pin header (for SPST switch used for program/run mode selection) 1 4-pin polarised header (for temperature sensor) 4 4-pin polarised headers (for TFT screen and backlight) 1 jumper shunt (for pressure sensor) Semiconductors 1 2N7000 N-channel MOSFET (Q3) 1 3mm red LED (LED2) Capacitors 5 100nF multi-layer ceramic GND 5V D10 D11 D12 (Notes) 1 WeatherDuino Pro2 RX PCB (M) 1 Arduino Nano v3.0 microprocessor module (H) 1 DS3231 real-time-clock Arduino module (A) 1 3V lithium battery (coin cell) for RTC 1 DHT22 temperature/humidity sensor (A) 1 BX-RM06 ASK OOK RF receiver (B) (K) 1 BMP180 (or BMP085) barometric pressure module (A) 1 SMA female board connector 1 Jumper (sets BMP module voltage) 1 momentary pushbutton switch, NO (E) 1 SPST pushbutton on/off switch (E) 1 display: either ST7735 1.8” TFT, OR 20 x 4 alphanumeric LCD, OR 16 x 2 alphanumeric LCD (A) 1 433MHz antenna (D) 1 case to suit (E) +9V– DHT22/SHT1X FAN FANLED A 100nF TXLED RAIN A Fig.2 (left): the WeatherDuino Pro TX PCB component overlay shown at 1:1 scale, with the blank PCB alongside. There are minor dfferences between the prototype boards and the final production boards. 74  Silicon Chip siliconchip.com.au Parts List – Wireless Display Unit 1 WeatherDuino Pro2 wireless display PCB (includes all SMD parts already soldered on) 1 5V DC power supply, fitted with mini-B USB plug 1 pushbutton switch, momentary, NO 1 SMA female PCB connector (Notes) (M) (E) (C) Semiconductors 1 Arduino Nano (H) 1 DHT22 temperature/humidity sensor (A) 1 BX-RM06 ASK OOK 433MHz RF receiver module (B) 1 3mm red LED (LED4) 1 display – one of: ST7735 1.8” TFT, or ILI0341 2.2” 20 x 4 alphanumeric LCD, or ILI934 2.4” 320 x 240 alphanumeric LCD or 20x4 LCD module OR 16 x 2 with I2C module (#) Capacitors 1 10µF/16V tantalum 3 100nF ceramic Optional components for Rx Unit (Highly recommended, needed if you want to relay data to a wireless display). 1 KXD-10036 433MHz transmitter module 1 433MHz antenna 1 2.5mm DC power socket 1 2N7000 MOSFET 1 3mm green LED 1 7809 9V positive voltage regulator 1 heatsink to suit 7809 Capacitors 1 10µF 16V tantalum Resistors (0.25W, 1% metal film) 7 10kΩ 1 180Ω Notes Table (#) See text for more detail Connectors (recommended, as it makes it a lot easier to connect and remove the PCB from its housing for later firmware updates, troubleshooting, etc). 1 5-pin polarised header (for touch screen interface) 1 SMA female board connector 1 4-pin header (for inside temperature sensor) Resistors (0.25W, 1% metal film) 1 10kΩ 1 470Ω (required for V4.03 PCB only) – please refer to listings last month for ebay item numbers A All these came from same ebay seller. B From supplier nominated, both pieces come together as a pair. These can be brought separately elsewhere but must match the picture as these types work best! C All these came from same ebay seller. D All these came from same ebay seller. E Up to the end user to choose the best for the application/ and desired look. F Also requires 12VDC power pack to suit (positive centre) G All these came from same ebay seller. H All these came from same ebay seller. I This came from the same seller as A (above). Please don’t use the included Receiver module in this pair. It’s not good (but the transmitter is good!). J Only required if you are using the I2C connector with a device that doesn’t have internal pull-up resistors on the SDA and SCL lines. K Can be omitted if you buy the KXD-10036 RF Transmitter/Receiver modules for the optional data relay as this part is included in the kit. M From www.meteocercal.info/forum/index.php plugpack. But if it’s not close to mains power, you could use a solar panel and 12V battery. The TX unit allows remote monitoring of the battery voltage so if using a battery, connect the +BAT terminal to the 12V battery (+) and the 12V terminal to the output of your solar charger controller. If you’re using a plugpack, simply connect the +BAT and 12V terminals together. Your TX unit should now be complete and ready for connection of the External Temperature Sensor. But first you need to attach it to a cable. Temperature Sensor As discussed last month, we opted for the SHT10 Temperature Sensor as we feel it offers the best “bang for buck”. Others might be more accurate but are also significantly more expensive. The SHT1x and the DHT22 use a serial protocol to pass information to the Arduino microprocessor. siliconchip.com.au SHT1X FRONT VIEW SHT1X REAR VIEW DH22 FRONT VIEW PCB designation Schematic Pin SHT1x pins DHT 22 pins GND 1 (GND) - 3 or 4 DAT 2 (D6) D 2 5V 3 (5V) + 1 CLK 4 (D9) S April 2015  75 ARDUINO LINGO: In Arduino-speak, software is known as “sketches”. And the add-on boards which plug into the Arduino are known as “shields”. The datasheet for these SHT1x sensors can be found here: www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/Humidity/Sensirion_Humidity_SHT1x_Datasheet_V5.pdf The WeatherDuino TX board also supports the SHT1X (and the SHT2X using the I2C port), so if your budget allows it, feel free to upgrade. However, if you go with the SHT2x module, you will need to visit the Meteocercal forum for the details required to use it. The ebay reference number we gave last month will take you directly to the SHT10 which has the senor already attached to a breakout board, making it easier to connect to the TX Unit. Sensor cable Make up a temperature sensor cable using a 4-pin connector (eg, Jaycar HM3404) and a length of good quality 4-core cable (maximum length 5 metres). Carefully solder the pins and heatshrink the other end of the cable to the sensor pins (or use a suitable plug to connect but remember, this needs to be protected as it is out in the open). Case Temperature sensor The TMP26 temperature sensor gives a voltage output proportional to the temperature. This is used only to monitor the temperature inside the TX unit case. However, it isn’t essential so if you want to save a little money, this can be omitted. Programming the Arduino Nano Programming is done by connecting the Nano to a PC USB port and running suitable software. While all this looks quite complex at first, in reality it’s fairly easy, especially for the TX unit. Once you’ve done these steps once, you shouldn’t need these instructions again. Ok, lets get started on some software fun. Finding the COM Port To program the Nano, you need to see what COM port is created when the Nano is connected to the host PC’s USB port. Before plugging in the Nano, open the Device Manager on the PC (Control Panel>Device Manager) and expand the “Ports (COM & LPT)” item by double clicking it. Now plug in the Nano and you should see a COM port created like that shown below left. If the icon beside it has an exclamation mark then you will need to install the driver. If you purchased the Nano from the ebay supplier listed last month, the required driver for the CH340G serial adaptor is called CH341SER.zip. You can download it from that seller’s site or from this thread at the Meteocercal forum www.meteocercal.info/ forum/Thread-Arduino-Nano-USB-Driver By the way, the Serial/USB converter onboard the Nano dictates which method of reset pullup we use later on the RX/WD boards, but we will cover that in the next part of the series. Keep the Nano plugged in and move on to the next step. Installing and configuring the Arduino IDE Download the Arduino integrated development environment (IDE) software from the Arduino.cc site. You will need the Arduino 1.5.8 BETA IDE as the code needs the extra optimisation that this beta release of the IDE gives, otherwise the code will not fit in the Nano’s 32KB flash memory. You can download the Arduino IDE here: http://arduino. cc/en/Main/Software#toc3 I’d recommend selecting and downloading the Windows Installer option from the above link (if, of course you are running Windows on this PC). Run the installer and give it a little while to install as it’s quite a large program with all the built in libraries. Once it’s installed open it. Then: 1. Click File then Preferences. Take note of the Sketchbook location. The path will have the name of the current logged in user. This is where we’ll extract the WeatherDuino software folders to. 2. While in Preferences, we recommend checking the 76  Silicon Chip siliconchip.com.au “Display line numbers” and “Automatically associate .ino files with Arduino” check boxes. Then click OK. 3. Next click Tools, then Board. Find and Select Arduino Nano. 4. Click Tools again, and then Processor. Select ATmega328. 5. Once again click Tools, then Port and then select the COM port that you saw in the step above. All good? Close the Arduino IDE and move to the next step. WeatherDuino software Now you need to download the WeatherDuino software (also called a sketch in the Arduino circles) from the Meteocercal forum site. Here is the link to the thread for the RX and TX unit: www.meteocercal.info/forum/Thread-WeatherDuinoPro2-RX-TX-Software-Latest-Release Save the .zip file to wherever is convenient. Now extract the .zip file to the location found in step 1 above. Choose OK to merge or replace the files. If the libraries are not in the right location the IDE will throw errors when you go to compile and upload the software to the Nano. You can manually ask the IDE to import the Libraries (menu/sketch/Import libraries) tho it’s easier just to put them where the IDE is expecting to find them. Browse to the WeatherDuino_Pro2_vXXX_XXXXXXXX in the location in step 1 above (The “x”’s will change depending on the version). Inside there should be three folders. Open the WeatherDuino_TX_vXXX_bXXX and inside that folder should be WeatherDuino_TX_vXXX_bXXX.ino, double click that and it should open in the Arduino IDE. Make sure it’s the file with TX in the filename. Configuring the WeatherDuino Pro TX options Now you should be looking a window that looks like this: articles, nothing needs to be changed here in the TX config (shown below) unless you need to alter the Stevenson Radiation Screen fan hysteresis (if used), or if you decided against going with the SHT10 temperature sensor, then you would need to alter this line to suit: #define ID1 0     // Temp / Hum data - 0 for SHT1x sensor, 1 for DHT22 sensor for say, a DHT22 temp sensor #define ID1 1     // Temp / Hum data - 0 for SHT1x sensor, 1 for DHT22 sensor An example of WeatherDuino TX user options section of the code: // ----------------------------------------------------------------------------//   User configurable options start here. // ------------------------------------------------------------------------------byte StationID = 0xA1; // Must be equal to your RX Unit (Value from 0x00 to 0xFF) byte UnitID     = 0; // If you use only one TX unit define it as UnitID = 0                          // For a second TX unit, define it as UnitID = 1 // ---------------- Let’s define the data we want to send ----------------//#define ID0       // SHT21 Sensor #define ID1 0     // Temp / Hum data - 0 for SHT1x sensor, 1 for DHT22 sensor #define ID2       // Wind data #define ID3       // Rain data //#define ID4       // UV / SolRad data #define ID5       // Hardware Status - System Temp, Battery Voltage etc byte fanOn_HiTemp = 32; // RS Fan turn on when outside temperature is >= than this value (°C) byte fanOn_LowTemp = 1; // RS Fan turn on when outside temperature is <= than this value (°C) byte fanOn_LowWind = 2; // RS Fan turn on when Wind Average is <= than this value (m/s) //------------------------------------------------------------------------------ Uploading the software to the WeatherDuino TX_unit You can read the comments which always start with “//” (the // tells the device not to run the code), doing so should make it fairly self explanatory what that line of code does. We will attempt to explain main config lines, where needed, that you need to change to get a working Weather Station suited to you location and set up. Any queries regarding changes to settings besides the usual basic configuration discussed in these articles, should be asked in the Metocercal forum (www.meteocercal.info/ forum). For this Weather Station we’re building in this series of 78  Silicon Chip If you have made changes, we would recommend saving them with a descriptive name (file/save as). Then it’s as easy as clicking the right arrow in the IDE to compile and upload the sketch. Normally it will work without error if configured correctly. But there’s two problems that can happen: 1. The IDE will give an error that the sketch won’t fit. That’s usually caused by not using the latest beta version of the IDE. 2. The IDE will give an error if it can’t find the libraries required. Check the location of the libraries or use the manual import function in the IDE (Sketch/Import Library). At this point you can disconnect the TX unit from the Host computer and when you power it up from a 12VDC power pack, you should have an operating TX unit sending data packets out over 433MHz. The green transmission LED should also blink when it does. The sensors and instruments Also at this point, it would be a good idea to read up on sensor and instrument placement. There are quite a siliconchip.com.au few “rules” on where specific sensors need to go to obtain correct readings. For example, the rain sensor needs to be located away from buildings so that any rain which falls into it is not subject to amplifying or shielding; the temperature sensor should ideally be located in a “Stevenson’s Screen”; wind sensors cannot be located in either a wind shadow or wind funnel and so on. The location will also govern where you would locate your TX unit and its sensor suite – and of course the cable run lengths required. There’s plenty of great information on the internet regarding this subject. A fairly good summary can be found here: www.wunderground.com/weatherstation/installationguide.asp Connecting the “Fine Offset” sensors: As mentioned in the first part of this series, the TX unit supports the Fine Offset weather station sensors. These look like this: The Anemometer The Wind Vane The Rain Gauge New! Compact, 94% Efficient Powerful DC-DC Converters KSDC-DCD100 100W Buck (Down) DC-DC Converter I/P Voltage: DC 4.5V-30V (16Amp) O/P Voltage: DC 0.8V-28V 12A(adj.) COMPACT 60mm x 52mm x 20mm $21.70 inc. GST inc. GST Plus $8.40 P&P KSDC-DCU-100 72W Boost (Step up) DC-DC Converter Input Voltage: DC10V=32V (10amps) Output: DC 12V to 35V (adj.) (6Amps) COMPACT 65mm x 58mm x 20mm $22.70 inc. GST inc. GST Plus $8.40 P&P Digital Panel Meters at Analogue Prices KSDVM-30 ULTRA-COMPACT 4.5-30VDC Digital Panel Meter Features: Bright 0.36” Red LED Digits, Snap-Fit Housing, Range optimized for solar, automotive & trucking applications. $6.70 Usually with the Fine Offset sensors, the Anemometer connects to the Wind vane via the common old flat 4-core telephone cable, using one pair. Then the Anemometer connects to the TX unit using the same cable. The Wind vane data goes via one pair to pins 1 & 2 and the Anemometer goes via the other pair to pins 3 & 4. The board has screen printed designations showing which RJ11 socket is which. If your sensors don’t usually connect in this fashion, then you will need to make or buy a splitter of sorts. Check the schematic – it shouldn’t be too difficult. You may even be able to use a phone line splitter (though not a ADSL splitter). Wind and Rain sensors are available via ebay and some online stores. Tip: By using multiple TX units, you can mount more than one sensor, in various locations. This is handy. for example, if your anemometer needs to be higher than the cable allows, or, another example, when you need to move the temperature sensor to a better or shadier position. To use more than one sensor, you need to alter this code and upload it to the second TX unit (the system supports a maximum of three TX units). A third unit can only be used with temperature/humidity and solar/UV sensors, not with rain or wind sensors. byte UnitID = 0; // If you use only one TX unit define it as UnitID = 0                          // For a second TX unit, define it as UnitID = 1 So this part of the series was fairly easy. huh? Good, as it was bit of a warm-up as the next part gets a little more involved with the configuration of the RX unit. And at the end of the next part you will have a fully operational weather station that’s capable of sending data to the Internet! See you then. 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