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9-Channel Infrared Remote Control Using a tiny, prebuilt 9-button remote, this infrared remote control receiver is ideal for use with TVs, hifi & audio-visual equipment, model train layouts and for robot control. Not only that but the one tiny handheld remote can be used to control up to three separate receivers, each with seven channels. No surface-mount parts are used in the design and it can run from a 12V battery or DC plugpack. By JOHN CLARKE I NFRARED REMOTE controllers are great but most universal remote controls tend to have lots of pushbuttons to cater for numerous functions and are quite bulky. If you only need a few functions, a much smaller remote is a lot more convenient. That is why this project uses a tiny IR remote from Sparkfun in the USA and available in Australia from Little­bird Electronics. Normally sold for use in Arduino projects, it’s used here with a dedicated receiver which controls up to nine output channels. Alternatively, it can control three independent receivers, with up to seven outputs each. That might sound a little confusing but the upshot is that this is a powerful control system with lots of options. The Sparkfun IR remote measures only 80 x 40 x 7mm and is powered by a 3V lithium CR2025 button cell. It has nine snap-action pushbuttons: on/off (shown with the Power logo), A, B and C, and a 5-switch array with “OK”, up, down, left and right. The 5-button array is ideal for volume and channel selectors or forward, reverse, left and right functions (eg, in a model railway system). The Sparkfun remote comes fully assembled and uses a 16-pin surfacemount IC, type HB8101P. It sends a unique code via an infrared LED for each of the nine pushbuttons. The infrared signal is in 38kHz bursts, in a format known as “Pulse Distance Protocol”. The controller has nine corresponding outputs and one of these will be switched if a valid code is received. The nine outputs can be switched by reed relays, open-collector transistors or a combination of both. The transistor outputs can be used to directly switch LEDs or to switch relays with higher contact ratings than those of the on-board reed relays. By the way, you don’t need to build the controller with all nine outputs if you don’t need them; just build it with as many as you need. Momentary or toggle? Each output can be set for momentary or toggle (sometimes called alter78  Silicon Chip siliconchip.com.au INTO RADIO? How about SiDRADIO? Take a Cheap DTV Dongle and end up with a 100kHz2GHz SoftwareDefined Radio! Published October 2013 It’sDon’t yours with the 200W pay $$$$ for a commercial Ultra LD Amplifier from receiver: this uses a <$20 USB DTV/DAB+ dongle as the basis for a very high performance SSB, FM, CW, AM etc radio that tunes from DC to daylight! Features:  Tuned RF front end  Up-converter inbuilt  Powered from PC via USB cable  Single PCB construction Lots of follow-up articles, too! The receiver can control nine output channels or can be built as an A, B or C device with seven output channels. Want to know more? Search for “sidradio” at siliconchip.com.au/project/sidradio PCBs & Micros available from PartShop Features & Specifications Features • • • • • • Uses pre-built miniature 9-button hand-held remote Nine output channels (single receiver unit) Optional A, B or C device (receiver) addressing with seven channels per device Reed relay outputs or open-collector outputs (suitable for a 12V DC coil relay) LED indicators Momentary or toggle operation on each output Specifications • • • • • IR reception range: 15m Power: 12VDC at 150mA minimum (increase the current rating for any added relay coil current) Output ratings: Reed relay contacts or open collector outputs, 24V <at> 500mA IR coding: Pulse Distance Protocol Reception frequency adjustment: ±12.5% in 16 steps (~1.5% steps) nate) operation. Momentary operation is where an output and its associated indicating LED is switched on only while the button for that function is being pressed. It goes off immediately when the button is released. For toggle operation, an output is set to switch on with one press of an siliconchip.com.au IR remote button and it will stay on until the same button is pressed again; a further press of the button switches the output off again. A pushbutton switch on the controller board is used to select momentary or toggle operation for each individual output and the unit remembers this MaxiMite miniMaximite or MicroMite Which one do you want? They’re the beginner’s computers that the experts love, because they’re so versatile! And they’ve started a cult following around the world from Afghanistan to Zanzibar! Very low cost, easy to program, easy to use – the Maximite, miniMaximite and the Micromite are the perfect D-I-Y computers for every level. Read the articles – and you’ll be convinced . . . You’ll find the articles at: siliconchip.com.au/Project/Graham/Mite Maximite: Mar, Apr, May 2011 miniMaximite: Nov 2011 Colour MaxiMite: Sept, Oct 2012 MicroMite: May, June 2014 plus loads of Circuit Notebook ideas! PCBs & Micros available from PartShop September 2015  79 Parts List 1 double-sided PCB, code 15108151, 132 x 87mm 1 front panel label, 148 x 45mm 1 9-button IR remote control, (LittleBird Electronics, Sparkfun COM-11759) – see either: http://littlebirdelectronics.com. au/products/infrared-remotecontrol or http://littlebirdelectronics.com. au/products/ir-control-kit-retail 1 CR2025 3V alkaline cell 1 UB1 plastic case, 158 x 95 x 53mm 1 SPST micro-tactile switch with 0.7mm (or similar length) actuator (eg, Jaycar SP-0600) (S1) 1 12V DC plugpack rated at 150mA or more (see text) 1 2.1mm or 2.5mm PCB-mount DC socket to suit plugpack (CON10) 9 2-way screw terminals, 5.08mm pitch (CON1-CON9) 1 cable gland to suit wiring 1 18-pin DIL IC socket 1 3-way DIL header (2.54mm spacings) 1 jumper shunt for header 3 PC stakes (TP GND, TP1, TP2) Semiconductors 1 PIC16F88-I/P microcontroller programmed with 1510815A.HEX (IC1) 1 TOSOP4838 or equivalent 38kHz IR receiver (IRRx1) (Jaycar ZD1952, Altronics Z1611A) 1 78L05 5V 100mA regulator (REG1) 9 high brightness 3mm red LEDs (LED1-LED9) 1 high brightness 3mm green LED (LED10) 1 1N4004 1A diode (D10) Capacitors 2 100µF 16V PC electrolytic 1 10µF 16V PC electrolytic 1 100nF MKT polyester Resistors (0.25W, 1%) 10 1kΩ 1 470Ω 1 100Ω Reed relay outputs* 9 SPST DIP 5V reed relays (Altronics S4100A, Jaycar SY-4030) (Relay1-Relay9) 9 1N4148 diodes (D11-D19) 9 100Ω 0.25W, 1% resistors Open collector outputs* 9 BC337 NPN transistors (Q1-Q9) 9 1N4004 diodes (D1-D9) 9 470Ω 0.25W, 1% resistors LK1-LK9 = resistor lead off-cuts * Adjust part numbers required for a mix of reed relay and open collector outputs setting even if the power is switched off. Note that all the outputs are always initially off whenever power is applied to the controller. mode, all nine outputs in the receiver unit are active and can be controlled by the remote. Three separate devices Now have a look at Fig.1 which shows the circuit details of the controller. It employs an infrared receiver/ decoder (IRRx1) and a PIC16F88-I/P microcontroller (IC1) which directly drives reed relays, NPN transistors or a combination of both, depending on how you configure the PCB. IRRx1 is a 3-lead device that comprises an infrared detector, amplifier, 38kHz bandpass filter and automatic gain control (AGC). Normally, IRRx1’s output is high (5V) and it goes low when it receives a 38kHz IR signal. The supply for IRRx1 is derived via a 100Ω resistor from the 5V rail and is decoupled by a 100µF electrolytic capacitor. IRRx1’s output connects to the RB0 As already noted, the Sparkfun remote can be used to select and control up to three separate devices, designated A, B and C. But if you want three separate devices, you need three separate receivers. So to select one of the three devices, you press button A, B or C on the remote and then the remaining buttons on the remote can be pressed to control the various functions on the selected receiver. The receiver incorporates three jumper positions that allow it to be set as an A, B or C device. Alternatively, if you don’t need to control multiple receiver units, you simply leave out the jumper. In this 80  Silicon Chip Circuit details input of IC1. IC1 in turn decodes the 38kHz signal to drive the outputs according to the infrared code sent by the handheld remote. Each output comprises an indicator LED driven via a 1kΩ resistor and either a 100Ω resistor which drives a reed relay or a 470Ω resistor which drives the base of an NPN transistor. Note that wherever a reed relay is used, a reverse-biased diode (D11D19) is used to clamp any transient voltage from the relay’s coil when it is switched off. By contrast, if a transistor is used instead, a diode (D1-D9) is used to clamp any transients from an external relay. Whenever the transistor is turned on, the external relay is enabled (turned on). Note that the circuit shows one output driven from RB1 (pin 7) and one driven by RA1 (pin 18) but seven other outputs are also available, depending on whether you install the relevant components on the PCB. The acknowledge LED (LED10) is driven via IC1’s RA6 output and flashes whenever an infrared signal is received. It’s turned on when signal from IRRx1 is detected by IC1 as a low and is off when IRRx1’s output is high. In addition, LED10 does doubleduty as a power indicator. When power is applied, it briefly flashes every second (ie, at a 1Hz rate) but flashes rapidly if an IR signal is received by IRRx1. The RB4, RB5, RB6 & RB7 inputs are normally high (+5V) unless pulled to 0V via momentary pushbutton switch S1 (for RB4) or the link options for the A, B or C inputs at RB7, RB6 & RB5. Only one jumper shunt should be used if the controller is to be used in its device mode (ie, with A, B or C). If more than one jumper is connected, say A and B, only A will be recognised. Note that if the Device A jumper is installed, then outputs B & C are disabled while the others all function normally. However, pressing either button B or C on the remote will always turn the A output off (if it’s on), while the other outputs will be left in their current state. These outputs will then not respond to further button presses on the remote unless the Device A button on the remote is pressed again. The Device B and Device C jumper options work in similar fashion, ie, a Device B jumper selection disables the receiver’s A & C outputs, while a Device C jumper selection disables the A & B outputs. siliconchip.com.au 12V DC INPUT + D10 1N4004 A +12V REG1 78L05 K – GND 100 µF CON10 OUT IN 10 µF 16V 10V OUTPUT LEGEND ON REMOTE BUTTON CON1 A CON2 B CON3 C R1-R9 = 100 Ω FOR RELAY OUTPUTS; 470 Ω FOR OPEN COLLECTOR OUTPUTS CON4 100Ω 100 µF IRRx1 λ 1 6 2 14 Vdd MCLR/ RA5 RB1 ACK RB2 TP GND λ LED10 RB3 DEVICE A 13 RB7 OSC1/RA7 RA0 DEVICE B 12 9 B TO TO TO TO TO 1 16 3 17 2 SC 20 1 5 A LED2, LED3, LED4, LED5, LED6, D12, D13, D14, D15, D16, K 7,8 CON2 CON3 CON4 CON5 CON6 K LED9 λ D1 – D10: 1N4004 6 K 2 CON9 D9 + A C B 1,14 CON9 – Q9 BC337 E EXTERNAL RELAY CONFIGURATION (R9 = 470 Ω) D19 A LK9 +12V RELAY9 A A 2 RELAY2/Q2+D2+LK2, RELAY3/Q3+D3+LK3, RELAY4/Q4+D4+LK4, RELAY5/Q5+D5+LK5, RELAY6/Q6+D6+LK6, 1k 18 5 D01 – D09: 1N4148 EXTERNAL RELAY CONFIGURATION (R1 = 470 Ω) TO R8, LED8, D18, RELAY8/Q8+D8+LK8, CON8 K 1 E TO R7, LED7, D17, RELAY7/Q7+D7+LK7, CON7 Vss IRRx1 R2, R3, R4, R5, R6, R9 RA1 CON1 C RB6 RB5 B 1,14 – Q1 BC337 ON-BOARD REED RELAY CONFIGURATION (R1 = 100 Ω) DEVICE C 11 A RA3 RB4 RA2 S1 (MOM. OR TOGGLE) 8 6 D11 λ 3 IC1 PIC1 6F88 6F8 8-- RA4 I/P 2 K 10 K A K RA6/OSC2 C RELAY1 1k 7 LED1 15 A R1 A CON1 + D1 CON8 TP2 470Ω A RB0 K CON7 CON9 4 TP1 LK1 +12V CON6 100nF 1k 3 CON5 +5V 7,8 ON-BOARD REED RELAY CONFIGURATION (R9 = 100 Ω) K 9–CHANNEL IR REMOTE CONTROL RECEIVER BC 33 7 LEDS K A 78L05 GND B E C IN OUT Fig.1: the circuit is based on infrared receiver/decoder (IRRx1) and a PIC16F88-I/P microcontroller (IC1). IC1 decodes the signal from IRRx1 and its outputs drive either reed relays (Relays1-9) or open-collector transistors (Q1-Q9). LEDs19 provide channel on/off indication, while the jumpers at IC1’s RB5-RB7 inputs provide optional device selection. If no device jumper is fitted, then no channels are disabled and the remote controls all of the receiver’s outputs. Frequency adjustment While the handheld remote and the controller are designed to operate with Pulse Distance Protocol, the actual times for each 38kHz burst and the off times can vary from specification. This is due to tolerances in the clocking rate for the code transmission and in measuring the transmission time periods. That’s because both the transmitter and controller ICs run using internal oscillators that are not precise. We have dealt with that by arranging for the microcontroller’s software to cater for up to a 10% variation in frequency siliconchip.com.au for the transmission rate and the detected time period. However, in some cases this may not be sufficient to reliably detect and decode transmissions. If that is the case, the software controller allows IC1’s internal oscillator to be shifted in frequency. The available range of correction is ±12.5%, with adjustment steps in either direction of about 1.5%. All of the relays and/or transistor outputs are powered from the +12V rail which is fed via reverse-polarity protection diode D10. The 5V supply for IRRx1 and IC1 comes from REG1, a 78L05 regulator. Its input and output are bypassed with 100µF and 10µF capacitors, respectively. In addition, IC1’s supply is bypassed with a 100nF capacitor close to the supply pins. Construction Building the Remote Control Receiver is easy, with all parts installed on a PCB coded 15108151 (132 x 87mm). This is housed in a UB1 plastic case measuring 158 x 95 x 53mm, while a 148 x 45mm panel label is affixed to the side. Figs.2 & 3 show the parts layouts for two different versions. Follow Fig.2 to build the unit with reed relay outputs or Fig.3 if you want open collector transistor outputs (eg, to switch external relays). Alternatively, you can have a mix of relay and open-collector outputs. It’s September 2015  81 DEVICE LED10 ACK. IC1 1k 100Ω 100 µF A K S1 Select GND Mom. or Toggle 10 µF 100nF PIC16F88 CON10 12V 78L05 Select A B C A,B,C or Nil 470Ω REG1 TP2 4004 TP1 (A) RELAY2 (B) RELAY3 (C) RELAY4 D1 2 4148 LED2 ( B ) A K 100Ω 1k D1 3 4148 LED3 ( C ) A K 100Ω 1k D1 4 4148 > LED4 ( ) A K 100Ω 1k CON5 CON6 ( ) RELAY7 ( >) RELAY8 ( ) RELAY9 RELAY5 RELAY6 D1 6 4148 LED6 ( ) A K LED7 ( > ) 1k 100Ω 15180151 D1 7 4148 1k 100Ω A K D1 8 4148 > LED8 ( ) A K ) 1k C 2015 15108151 A K 1k 100Ω D1 9 4148 100Ω > (< ) CON7 100Ω 1k CON8 A K ( ) CON9 D1 5 4148 LED5 ( < ) LED9 ( RELAY1 CON1 100Ω 1k CON2 A K CON3 D1 1 4148 LED1 ( A ) D10 100 µF CON4 > IRRx1 IR REMOTE CONTROLLER ALL CHANNELS CONFIGURED WITH ON-BOARD RELAYS Fig.2: follow this PCB layout to build the unit with reed relay outputs. A jumper is shown here in the Device A position but this should be omitted if you only want a single 9-channel receiver. just a matter of referring to either Fig.2 or Fig.3 and installing the appropriate output components for that channel. As shown in the photos, our prototype was built with open-collector transistors for outputs A, B & C and reed relays for the remaining six out- puts. Note that the output channel symbols match the buttons on the remote control. Note also that if you plan to set the controller for device operation, you don’t need to fit the output components for the disabled channels. For Front Panel Labels The front-panel label is optional. It can be made by downloading the relevant PDF file from the SILICON CHIP website and then printing it out as a mirror image onto clear overhead projector film (use film that’s suitable for your printer). By printing a mirror image, the toner or ink will be on the back of the film when it’s fitted. The label can be secured in place using white or grey silicone adhesive. Alternatively, you can print onto a 82  Silicon Chip synthetic Data­flex sticky label if using an inkjet printer or onto a Datapol sticky label if using a laser printer. (1) For Dataflex labels, go to: www.blanklabels.com.au/index. php?main_page=product_info& cPath=49_60&products_id=335 (2) For Datapol labels go to: www. blanklabels.com.au/index.php? main_page=product_info&cPath =49_55&products_id=326 Our prototype PCB was built with open collector transistors for outputs A, B & C and reed relays for the remaining six outputs. example, if the controller is to be an A device, then the B and C output components (including LEDs 2 & 3) do not need to be installed. Similarly, you can leave out the output components for any other channel that isn’t required but note that LED1 is required for Device A operation since this is the Device A indicator. Alternatively, you will need to install LED2 for Device B operation or LED3 for Device C operation. If sorting that out all sounds too hard, then you can just install all the parts for each output channel. Begin the assembly by fitting the resistors. Table 1 shows the resistor colour codes but you should also check their values using a DMM before soldering them to the PCB. Be sure to fit the correct values for resistors R1-R9. 100Ω resistors must be installed for the reed relay channels, while 470Ω resistors are used with the open collector transistors. The diodes go in next. Note that D11-D19 on Fig.2 are 1N4148 types, while D1-D9 on Fig.3 are 1N4004s and occupy different positions. D10 is a 1N4004 on both versions. Take care to ensure that the diodes are all orientated correctly. Next, fit the PC stakes for TP1, TP2 and TP GND, then install an 18-pin DIL socket for IC1 (notched end to the left). The capacitors can then be soldered in place, taking care to ensure that the three electrolytics are oriensiliconchip.com.au DEVICE S1 GND Select Mom. or Toggle 10 µF CON10 12V 78L05 100nF PIC16F88 IC1 1k 100 µF 100Ω LED10 ACK. A K Select A B C A,B,C or Nil 470Ω REG1 TP2 4004 D7 4004 Q7 BC337 470Ω 1k D8 > LED8 ( ) 4004 A K D9 4004 Q9 BC337 470Ω 1k – LK9 ) C 2015 15108151 + Q8 BC337 470Ω 1k – + ( ) (< ) ( ) ( >) ( ) > A K + LK8 A K + – LK7 15180151 LED7 ( > ) Q6 BC337 470Ω 1k CON1 4004 A K – LK6 D6 LED6 ( ) + CON2 Q5 BC337 470Ω 1k CON3 4004 A K – LK5 D5 LED5 ( < ) + > Q4 BC337 470Ω 1k (C) CON4 > 4004 A K + – LK4 D4 LED4 ( ) Fig.4 shows how the LEDs are installed. As shown, their leads must be bent down by 90° exactly 6mm from their bodies and that’s best done using a 6mm-wide cardboard template. Make sure that each LED’s cathode (K) lead (the shorter of the two) is facing Q3 BC337 470Ω 1k (B) CON5 4004 A K + – LK3 D3 LED3 ( C ) LEDs & infrared detector Q2 BC337 470Ω 1k (A) CON6 4004 A K + – LK2 D2 LED2 ( B ) LED9 ( Q1 BC337 470Ω 1k CON7 4004 A K tated correctly. The 100nF polyester (MKT) capacitor can be fitted either way around. Follow with the DC socket and switch S1, then install transistors Q1Q9 (as required) and regulator REG1. Links LK1-LK9 can now be installed in those channels where a transistor is fitted. These links are only very short (less than 5mm) and can be fashioned using resistor lead off-cuts. The 3-way DIL header for device selection is installed near IC1. Its short pin lengths go into the PCB, while the longer pin lengths on top accommodate the jumper shunt (if fitted). Screw-terminal blocks CON1-CON9 can now all be installed. Make sure that they sit flush against the PCB and that their wire entry holes are to the right before soldering their pins. LK1 D1 LED1 ( A ) D10 100 µF CON8 TP1 CON9 IRRx1 – IR REMOTE CONTROLLER ALL CHANNELS CONFIGURED WITH OPEN COLLECTOR OUTPUTS Fig.3: here’s how to build the unit with open-collector transistor outputs. You can have a mixture of outputs on the same board if you wish – just configure each channel according to the relevant PCB layout diagram. 6mm IRRx1 HOW TO BEND THE LED LEADS 15mm 15mm 6mm PCB 5mm Fig.4: each LED has its leads bent down through 90° exactly 6mm from its body before installation on the PCB. That’s best done using a 6mm-wide cardboard template. Note that the LEDs are soldered to the PCB only after the latter has been installed in the case (see text). 5mm PCB Fig.5: the diagram shows how to bend the leads of infrared receiver IRRx1. Bend the leads around 5mm and 6mm-wide cardboard templates and make sure that the centre of the lens is 15mm above surface of the PCB when soldering the device in place. Table 1: Resistor Colour Codes o o o o siliconchip.com.au No. 10    1    1 Value 1kΩ 470Ω 100Ω 4-Band Code (1%) brown black red brown yellow violet brown brown brown black brown brown 5-Band Code (1%) brown black black brown brown yellow violet black black brown brown black black black brown September 2015  83 A B C Ack + + + + + > Power 12V DC + + On-board relay contacts: 24V, 500mA max. + > + > + . IR Remote Control Receiver > + + SILICON CHIP Outputs On-board relays: 24V max. <at> 500mA + . 12V DC Fig.6(a): use this front-panel artwork if you are building a single unit to control nine output channels. It can either be copied or downloaded in PDF format from the SILICON CHIP website and printed onto clear film or a sticky label (see text). The rear panel artwork is shown to the right. A B C Ack + + + + > + Outputs Device On-board relays: 24V max. <at> 500mA + . 12V DC + Power 12V DC + On-board relay contacts: 24V, 500mA max. + > + > + . IR Remote Control Receiver > + + SILICON CHIP Fig.6(b): use these artworks if you are building more that one receiver and will be using device selection. Note that either of the above two front-panel artworks can be used as a drilling template for the case. Rear-panel drilling template 65mm A = 12mm diameter B = 11mm diameter A + 25mm 27mm B + 22mm Fig.7: this is the rear-panel drilling template. The two holes are best made by first drilling small pilot holes and then carefully enlarging them to size using a tapered reamer. towards you before bending its leads down, so that the LEDs go in with the correct polarity. Don’t solder the LEDs to the PCB at this stage though – that step comes later, after the PCB has been installed in the case. Having prepared the LEDs, you can now bend the infrared detector’s leads as shown in Fig.5. Again, that’s best done using cardboard templates, one 6mm wide and the other 5mm wide. Use the 6mm template to first bend the leads back by 90°, then use 84  Silicon Chip the 5mm template to bend them back down again. Having bent IRRx1’s leads to shape, solder it in place with the centre of its lens exactly 15mm above the PCB. Fig.5 shows the details. Drilling the case The assembled PCB (minus the LEDs) can now be put aside while you drill the UB1 plastic case. Figs.6(a) & (b) show the alternative front panels for the receiver and you can make a photocopy and use either one as a drilling template. Alternatively, you can download the labels as a single PDF file from the SILICON CHIP website and print them out. You need to drill 3mm-diameter holes for the 10 LEDs and a 6mm hole for infrared receiver IRRx1. Deburr all holes using an oversize drill, then drill two holes in the rear panel using the template shown in Fig.7 – one to provide access to the DC socket and the other to mount a cable gland. The DC socket hole has a diameter of 11mm, while the cable gland hole is siliconchip.com.au Fig.8: the top trace of this scope grab shows the output from IR detector IRRx1, while the lower trace is the Acknowledge LED voltage and shows the processed and decoded signal from the microcontroller. The initial 9ms pulse and 4.5ms gap indicate the start of the sequence (note: the coding shown is for the remote’s power button). Fig.9: this scope grab shows the button repeat signal pulses. The top trace is IRRx1’s output, the lower trace is the Acknowledge LED’s decoded output. Fig.9: the bottom trace here shows the bursts of 38kHz signal as sent by the remote’s IR LED, while the top trace is the demodulated output from IRRx1. Note that IRRx1’s output is low when the 38kHz IR signal is present. The rear panel carries the cable gland and also has an access hole for the DC power socket. 12mm in diameter. They are best made using a small pilot drill to begin with and then carefully enlarged to size using a tapered reamer. Now take a look inside the case. You will find that one of the LED holes goes through one the internal plastic ribs, while another hole will be immediately adjacent to one of these ribs. You will need to cut away the ribs from around these holes using sharp side cutters, so that the LEDs will later fit correctly. Final assembly Once all the holes have been drilled, the PCB can be slid into the case and clipped into the slots in the integral side ribs. Check that the PCB is the right way siliconchip.com.au Fig.10: this shows an expanded view of the IR signal’s 38kHz carrier frequency. The carrier is sent as a series of on and off pulses; ie, it’s switched on and off with a particular pattern to identify a particular button. September 2015  85 This view shows the completed remote control receiver. It’s powered using a 12V DC plugpack rated at 150mA or more. Compensating For Frequency Tolerances Normally, you will not need to compensate for transmission rate tolerances. However, if the receiver fails to operate reliably, you will need to adjust IC1’s clock rate. The procedure is as follows: (1) Switch off the power to the receiver, then reapply power while holding S1 down. (2) Continue holding S1 down; LED5 (the centre LED in the row on nine) will light to indicate the current oscillator setting (this is the default “zero change” setting). (3) Release S1; LED 5 will turn off and the Acknowledge LED (LED10) will turn on to indicate that the receiver is now in the oscillator adjustment mode (it can still flash if it receives a signal from the remote). (4) Press switch S1 again. LEDs 5 & 6 will now both light to indicate that IC1’s oscillator frequency has been slowed. (5) Release S1 and test the receiver using the remote to see if it now operates reliably. In not, press S1 again; LED6 will now be lit on its own, indicating a further slowing of the oscillator frequency. Check the unit once again to see if it now operates reliably. (6) Pressing S1 again will now light LEDs6 & 7, then LED7 on its own, then LEDs7 & 8 and so on up to LED9, with each step progressively slowing IC1’s oscillator. Check for reliable operation after each step. (7) Pressing S1 after LED9 has been lit moves the display back to the left (ie, towards LED1). When LED5 is reached, pressing S1 again will light LEDs5 & 4. This indicates that the frequency has been increased by one step from the default value. Further presses of S1 then light LED4, then LEDs4 & 3, then LED3 on its own, then LEDs3 & 2 and so on, with each step increasing the frequency. (8) Once you’ve found a setting that gives reliable operation, switch off and then reapply power to get out of the frequency adjustment mode. The Acknowledge LED should now resume normal operation (ie, it will flash briefly at a 1Hz rate to indicate that power is applied, or flash rapidly if a signal is received from the remote). around – the pads for the LEDs must be adjacent to LED holes in the side of the case. The 10 LEDs can now be fitted in 86  Silicon Chip place and their leads soldered to their pads on the top of the PCB. Check that each LED is correctly orientated and that it protrudes through its front- panel hole before soldering its leads. LEDs1-9 are all red LEDs while LED10 (Power/Acknowledge) is green. Now check that the infrared detector’s lens is correctly aligned with its front-panel hole. If not, bend its leads until it’s centred. Testing Now for the smoke test. Apply power using a 12V DC plugpack and check that the voltage between pins 14 & 5 of IC1’s socket is close to 5V (4.855.15V). If no voltage is present, check diode D10’s polarity and check the polarity of the plugpack supply (the centre of the plug should be positive). Make sure also that REG1 is correctly orientated and that all leads have been correctly soldered to their PCB pads. If the supply checks out, switch off and install IC1, making sure that its notched end faces towards LED10 and that all its pins go into the socket correctly. That done, reapply power and check that the hand-held remote can activate each output. By the way, you will need to insert a CR2025 cell into the remote before using it. The cell’s tray is accessed from the bottom edge of the case. It’s opened by first pulling its locking tab sideways (towards the centre) and then sliding the tray out (it may require some force to move it). The cell is then installed with its negative side towards the pushbutton (top) side of the case. By default, the outputs are all configsiliconchip.com.au Driving Devices Using The Open Collector Outputs RELAY 1 CON X 390Ω RELAY 2 + + – – NO NC NC CON Y A CON 1-9 + λ LED – NO K Fig.11(b): driving a LED output. MOTOR 390Ω + VOLTAGE TO SUIT MOTOR Fig.11(a): using two open collector outputs to drive a motor in both directions: (1) Both outputs set for momentary operation Pressing (and holding) the button for open-collector output “X” activates Relay 1 and causes to the motor to rotate one way, while pressing the button for output “Y” activates Relay 2 and causes the motor to rotate the other way. 1 CON 1-9 + 4N28 OPTOCOUPLER 5 λ – 4 2 Fig.11(c): driving an optocoupler. (2) Both outputs set for toggle operation The motor will be stopped until one of the outputs is toggled (its direction will depend on which output is turned on). The motor can then be reversed by toggling both outputs or stopped by toggling either output. (3) One output set for toggle and the other momentary operation The motor will run continuously in one direction if the toggle output is on or in the other direction for as long as the momentary output is on while the toggle output remains off (ie, it runs while the button on the remote is pressed). ured for momentary operation. If you want toggle operation for an output, press and hold S1 on the receiver’s PCB, then press the required button on the remote and release S1. Switching back from toggle to momentary operation is done the same way If you find that the unit doesn’t operate reliably, or only works with certain orientations of the remote, it may be due to frequency tolerances. In that case, it’s just a matter of altering IC1’s frequency to improve the IR code detection. The accompanying panel (Compensating For Frequency Tolerances) describes how that’s done. If the unit fails to work at all, check your soldering and check that all parts have been correctly placed and orientated. Front panel Assuming that it’s all working correctly, all that remains now is to fit the front panel. As shown in Figs.6(a) & 6(b), there are two to choose from. Use 12V RELAY CON 1-9 + – NO C NC Fig.11(d): driving a 12V relay. Fig.6(a) if you are simply using the unit to control nine output channels and don’t need device selection (ie, you don’t need to select another receiver). Alternatively, if you are using device selection (eg, you have two or more receivers), use the front panel shown in Fig.6(b). Don’t forget that you will need to install a jumper on the 3-way pin header (near IC1) on the PCB to select either device A, B or C. An accompanying panel describes how to make a front panel using either Are Your S ILICON C HIP Issues Getting Dog-Eared? $ REAL VALUE AT Are your SILICON CHIP copies getting damaged or dogeared just lying around in a cupboard or on a shelf? Can you quickly find a particular issue that you need to refer to? 16.95* PLUS P &P Keep them safe, secure and always available with these handy binders Order now from www.siliconchip.com.au/Shop/4 or call (02) 9939 3295 and quote your credit card number. *See website for overseas prices. siliconchip.com.au September 2015  87 Pulse Distance Protocol (PDP) Most infrared (IR) controllers use a modulation frequency somewhere between 36kHz and 40kHz – typically 38kHz. This is the frequency at which an infrared LED is switched on and off when a signal code is sent to the receiver. A series of 38kHz signal pulses is called a “burst” and is inter-spaced with a pause during which no IR signal is sent. This series of bursts and pauses usually conforms to a particular format or protocol and there are several in common use. These include the Manchesterencoded RC5 and RC6 protocols as used by Philips, while Sony uses the Pulse Width Protocol. By contrast, the remote used in this project uses NEC’s Pulse Distance Protocol. Further details on all these protocols can be found in application note AN3053 by Freescale Semiconductor (formerly Motorola) – see: http://cache. freescale.com/files/microcontrollers/ doc/app_note/AN3053.pdf Fig.12 shows the basics of the Pulse Distance Protocol. Logic 1 and logic 0 both comprise an initial 560μs-long 38kHz burst. Each logic 1 is followed by a 1690μs pause but a logic 0 is followed by a shorter 560μs pause (ie, the same length as the logic 0’s 38kHz burst). The entire data stream uses a 9ms burst and a 4.5ms pause starting train. The following data consists first of the address bits and then the command bits. The address identifies the handheld remote, while the command bits correspond to the buttons on the remote. Note that the address and command data is sent with the least significant bit transmitted first. The data comprises an 8-bit address, after which a complementary 8-bit address is sent. This is essentially the opposite bit of the address that’s sent. So for every “0” bit that’s sent in the address, a “1” will be sent in the complementary address. Similarly, for every 1 that’s sent in the address, a 0 will be sent in the comple- clear film or a Dataflex or Datapol sticky label. Once you have the label, remove the PCB from the case, then affix the label in position and cut out the holes using a sharp hobby knife. Output connections The reed relays are ideal for switching low voltages (up to 24V maximum) 88  Silicon Chip Logic Bit Encoding Data Frame Sequence Repeat Frame Overall Sequence Fig.12: the basics of the Pulse Distance Protocol (PDP). The data stream consists first of the address bits and then the command bits (see text). mentary address. The command bits are also resent in complementary form. As an aside, if you look up the address and command values that the remote produces (see https://learn.sparkfun. com/tutorials/ir-control-kit-hookupguide), you will see that the address is 10EF hex. In addition, the operate button code is D827 hex. 10 hex is the address value and EF hex is the address complement value. These values are in hexadecimal format (ie, values from 10-15 are designated A-F). The complementary address and command bytes are sent so that they can be compared to detect errors. If the complementary data value received and currents up to 500mA. They can be used to duplicate pushbutton switches on equipment by wiring the reed relay output in parallel with the switch. If switching inductive loads, then a reverse-biased diode should be connected across the relay’s contacts. Do not under any circumstances use the on-board reed relays to switch doesn’t match the complement of the data value received, the signal has been corrupted somehow (eg, due to interference). Alternatively, the received data may not be PDP protocol data, which means that the signal is being sent by a different hand-held remote. Following the address and command data, an end (or tail) comprising a 560μs burst is sent to complete the data frame. Any further holding of the hand-held remote’s button will then produce a repeat frame. This consists of a 9ms burst followed by a 2.25ms pause and then a 560μs burst. The repeat frame is repeated at 110ms intervals while ever the remote’s button is held down. mains voltages. That would be dangerous since neither the relays nor the PCB tracks are designed to handle high voltages. If you do need to switch high voltages, use either the reed relay or the open-collector transistor outputs to switch appropriately-rated external SC relays. siliconchip.com.au