Fullscreen HTML5Med Res (??MB)HTML4

The receiver board at right is capable of 16 channels & you can build up to four to give 64 channels. In practice, one receiver board would be built to control each piece of equipment. A smart remote control with up to 64 channels Have you ever wanted to control a tuner, CD player, VCR or any other device that does not have its own remote control. If so, this project is for you. It was developed to control a tuner & a cassette deck but it could be made to control almost any­thing using the right interfaces. By BRIAN ROBERTS 64  Silicon Chip This project is extremely flexible and uses a universal infrared remote control. These “intelligent” or “learning” remote controls are readily available and can also replace the existing remote controls for your TV, VCR and other equipment. For my application, I required 12 channels for the tuner and eight for the tape deck. I did not want messy wires connect­ing between a remote control receiver and both of these units so the unit was designed to be address selectable which allows a receiver to be fitted inside each unit. This means, for example, that the tuner operates on channels 1-8 and 33-40 and the tape deck on say 9-16. If I needed to remote PARTS LIST Transmitter board The transmitter board (above) is used to teach codes to a learning remote control unit. Up to 64 codes are possible by changing the DIP switch settings & a single link. control another device, it would occupy addresses 17-24 and 49-56. Because the receiver units were fitted internally in my installations, they ran off the power rails in the controlled de­vice. The current drain is small, at approximately 25mA. Alterna­ tively, you could have external receivers which will require their own small power supplies and a multi-way cable to perform the control functions. Each receiver board is capable of handling 16 channels, so to provide a total of 64 channels you would need four separate receiver boards, each of which is programmed via linking options to decode its own 16 channels. The receiver board has two channels capable of either momentary or latched operation for switching relays that turn on and off high current loads. The two outputs per board can be configured for normally on or normally off operation and are capable of sinking 75mA from any rail up to and exceeding 16V. If this feature is used, there is a maximum of 56 channels available (14 per board). Circuit description The circuit of the transmitter board is shown in Fig.1. The transmitter is built up only to provide a source of codes which can be “learnt” by an intelligent remote control. After this is done, the transmitter board is not used. IC1 is an MV500 remote control 1 PC board, code 15105942, 47 x 36mm 1 MV500 remote control (IC1) 1 2N2222 NPN transistor (Q1) 1 CQY89A infrared LED (L1) 1 8-way DIP switch 1 4-way DIP switch 1 2-pin header 1 jumper shunt 1 Murata CSB500E 500kHz ceramic resonator (X1) 1 6V battery & snap connector 2 100pF ceramic capacitors 1 47kΩ 0.25W resistor 1 10kΩ 0.25W resistor 1 47Ω 0.25W resistor Receiver PC board (for 16 channels) 1 PC board, 80 x 86mm, code 15105941 8 4-way pin headers 1 8-way dual pin header 1 2-way dual pin header 4 jumper shunts Semiconductors 1 MV601 infrared decoder (IC1) 1 SL486 infrared preamplifier (IC2) 1 74HC138 3-to-8 line decoder (IC3) 2 4028 BCD to decimal decoders (IC4,5) 1 74HC74 dual D-type flipflop (IC6) 1 4071 quad 2-input OR gate (IC7) 4 4066 quad analog switches (IC8,9,10,11) transmitter IC. Pins 2-9 are the keypad row pins and pins 10-13 are the column pins. The keyboard is scanned in the conventional way and if a key is pressed, the transmitter will deliver a code relevant to that row/column combination. In this circuit, no keypad is used but DIP switches 1-8 and 9-12 provide all the combinations of a 32button keypad. Pins 14 and 15 control the output pulse frequency. SW13 is a link option which ties pin 14 high if inserted while resistor R3 ties this pin low if not. Therefore, two transmitting rates are possible. With the link present, the 1 LM358 dual FET-input op amp (IC12) 1 LM317T adjustable 3-terminal regulator (REG1) 2 BC549 NPN transistors (Q1, Q2) 1 red LED (LED1) 1 BPW50 infrared photodiode (IRD1) 1 1N914 diode (D1) Capacitors 1 68µF 16VW tantalum electrolytic 1 22µF 25VW electrolytic 1 10µF 16VW electrolytic 1 6.8µF 16VW tantalum electrolytic 1 4.7µF 16VW electrolytic 1 0.47µF monolithic 1 0.15µF metallised polyester (greencap) 3 0.1µF monolithic 1 .022µF metallised polyester (greencap) 1 .015µF metallised polyester (greencap) 2 .0047µF metallised polyester (greencap) 2 100pF ceramic Resistors (0.25W, 5%) 1 1MΩ 2 3.3kΩ 1 120kΩ 1 1kΩ 1 100kΩ 1 270Ω 1 27kΩ 1 240Ω 1 10kΩ 1 47Ω 1 4.7kΩ Note: PC boards for this project will be available from RCS Radio Pty Ltd. Phone (02) 587 3491. transmitted rate is 512 clock cycles (fast rate); otherwise it is 2048 clock cycles (slow rate). Pins 16 and 17 connect to ceramic resonator X1 and ca­pacitors C1 and C2 which form an oscillator circuit of 500kHz from which all timing is derived. Q1 is the output driver which is turned on and off by the current pulses from pin 1. L1 is the infrared LED and resistor R1 limits the current to a safe value. Now let’s have a look at the circuit of the receiver board – Fig.2. The signal from the remote control is May 1994  65 +3-6V SW9-12 SW-DIP4 R2 10k 8 1 7 2 6 3 5 4 13 VDD 12 C1 11 C2 SW13 (LINK) 15 RA RB 14 8 9 10 6 11 5 12 4 13 3 14 2 15 11 16 7 R2 6 R3 5 R4 4 R5 3 R6 2 R7 SW1-8 SW-DIP8 R1 47  R3 47k 10 C3 9 R0 8 R1 L1  CQY89A K B OUTPUT 1 7 A C E IC1 MV500 C2 100pF OSC 17 OSC Q1 2N2222 Fig.1: the circuit of the transmitter. IC1 generates a serial pulse code according to the settings of the DIP switches. 32 codes are possible and the total of 64 codes are obtained by varying the pulse rate low or high. X1 500kHz 16 C1 100pF VSS 18 B R C VIEWED FROM BELOW A K 66  Silicon Chip 6 (ie, pulses are fast), the output at pin 7 will switch high and this toggles the rate pin (pin 3) of IC1 so that it has the correct rate selected. We’ll come back to this factor in a moment. IR pulse decoder IC1, the MVA601 infrared pulse decoder, is really the heart of the circuit. Its timing is by the 500kHz ceramic resonator at its oscillator pins (6 & 7). IC1 decodes the pulses from IC2 and the decoded result is presented on five data lines D0-D4 which gives 32 possible channels (ie, 25). You will note that there is one extra data bus line (D5) on the circuit which comes from comparator IC12b. As the decoder chip can only provide 32 independent codes and the design called for 64 codes, we cheat by using the rate of the pulses to give the extra 32 codes. If the rate of the pulses is fast, then D5 is high. Conversely, if the rate is slow then D5 is low. We now have 32 combinations when the pulse rate is fast and 32 when the pulse rate is slow. Pin 10 of IC1 is the Data Ready pin and it goes low to light LED 1 when a valid code has been received. IC3, IC7, IC5 and IC4 convert the binary data (D0-D5) from IC1 to 16 decoded outputs. IC3 is a 74HC138 3-to-8 line decoder. Dependent on the data on its pins 1, 2 & 3, one of its eight outputs will go low. If the data was 00000 for D0-D5 and the links on PL1 & PL2 are as shown on the schematic, then the following Construction Let’s discuss construction of the transmitter first. It is built on a PC board measuring 47 x 36mm and coded 15105942 – see Fig.3 Mount all the Fig.2 (right): the circuit of the receiver board can decode up to 16 channels. Four receivers are required to give a total of 64 channels. IC1 is the heart of the circuit & it decodes the serial data from IC2 & presents it as parallel data on lines D0-D5. This parallel data is then decoded by IC3, IC4 & IC5 to drive the 4066 bilateral switches (IC8-11). ▲ received by infrared photodiode IRD1 and then processed by IC2 which is an SL486 infrared preamplifier chip with AGC. This IC has a number of features that ensure operation under a wide range of operating conditions. The chip has a differential input stage to minimise noise, while capacitors C2 and C3 are part of the gyrator circuitry to roll off the frequency response below 2kHz so that the attenua­ tion at 100Hz is approximately 20dB. C9 further reduces the gain below 2kHz in the first stage of the chip. The output signal from pin 9 is coupled back into the stretch input (pin 10) via capacitor C10 to lengthen the very narrow received pulses. This is done to make the rate detector formed by IC12 operate with wider margins. It also provides noise immunity as the stretch input has a threshold below which any noise spikes are ignored. The stretched pulses from pin 11 are fed via op amp IC12a and then to pin 1 of IC1, the infrared pulse decoder. The output of IC12a is also fed via diode D1 to a circuit that detects whether the pulse frequency is fast (output is high) or slow (output is low). Resistors R7 and R4 and capacitor C11 form a filter circuit for the rectified pulses from D1 and, depending on whether the pulse frequency is high or low, the filter voltage will be high or low. Op amp IC12b is connected as a comparator to monitor the filter voltage. If pin 5 is more positive than pin conditions occur. Pin 15 of IC3 would be low as a valid code (000) is being received which means that pin 8 of IC7c is also low. Pin 10 of IC1 (Data Ready) would also be low, so pins 9 and 2 of IC7 would also be low. Pin 10 of IC7c would then go low to drive the D input of IC4, a 4028 BCD-to-decimal decoder. This then turns on bilateral switch IC8 and channel 1 is enabled. The purpose of the dual 8-pin headers PL1 and PL2 is to allow link selection of a block of any 16 channels from 64. This ena­bles us to have multiple decoders which allow the flexibility talked about in the introduction – see Table 1. IC6a is a latch and channel 39 can be selected for latched operation by linking the pins of header SW1a, or for momentary operation by linking across SW1b. The same applies to IC6b and channel 40 (link SW2a for momentary operation and SW2b for latched). The time constant consisting of R12 and C1 ensures that latch IC6 has its pins 9 and 5 low at power up. The Q outputs of IC6 turn on transistors Q1 and Q2 which can sink more current than the bilateral switches. If the transistors are fitted, then IC11 is omitted and vice versa. The solder straps indicated by the dotted lines on the circuit diagram of Fig.2 allow the transistors to be normally off or normally on by se­lecting either the Q or Q-bar outputs from IC6. REG1 is an LM317 3-terminal adjustable regulator which is set to provide an output of +6.3V. This is a compromise supply between IC1’s maximum operating voltage of 7V and the desire to obtain a low on-resistance in the bilateral switches (IC8-11). VCC C7 .0047 R10 47  C6 .022 5 4 C2 6.8 2 C3 68 3 C5 10 IRD1 BPW41 C8 0.15 8 16 A 6 11 3 DEC4 OVCC DEC2 IVCC SOUT C1 IC2 SL486 DECA A C O/P 9 C10 .0047 DEC1 DEC1 1 IC12a 2 LM358 11 C2 R6 1M 8 D1 1N914 R3 4.7k  K R5 10k 7 C9 15 .015 C11 0.47 IC12b 10 B C 10 11 I/OA 6 CC 12 I/OA CD 5 I/OB CB 13 I/OB CA IC8 4066 I/OC I/OC I/OD 3 Q0 14 Q1 2 Q2 IC4 Q3 15 4028 1 Q4 6 Q5 7 Q6 4 Q7 VCC 14 14 16 D 7 I/OD 8 I/OA 6 CC 12 I/OA CD 5 I/OB CB 13 I/OB CA IC9 4066 I/OC I/OC I/OD I/OD VCC 16 1 10 A 13 B 12 C IC7a 11 3 2 +9-16V C4 22 IN IN REG1 REG1 LM317 LM317 ADJ R8 1k 11 D0 12 D1 OB 13 D2 OC A RB B C VCC OD OE OUT 7 R1 1k 14 D3 11 6 16 15 14 13 12 Y0 A E3 2 Y1 B 3 Y2 C IC3 Y3 74HC138 Y4 4 Y5 E1 5 Y6 E2 Y7 15 D4 D5 C13 100pF OUT R9 240  C12 4.7 CH1-8 CH9-16 1 2 3 1 2 3 CH17-24 CH25-32 CH33-40 4 11 5 6 7 D 4 5 CH41-48 6 CH49-56 7 8 8 CH57-64 PL1 PL2 1 2 3 4 E F 1 2 3 4 PL4 8 9 10 1 2 3 11 4 CH4 14 D 1 2 3 4 8 9 10 11 1 2 3 4 PL6 1 2 3 4 Q7 8 R12 100k C1 0.1 0.1 INTELLIGENT REMOTE CONTROL 1 PL7 2 CH36 6 CC 12 CD 5 IC10 CB 4066 8 13 I/OC CA 9 I/OC 10 I/OD 11 I/OD CH1 CH2 VCC PL5 VCC I/OA 1 2 I/OA 3 I/OB 4 I/OB CH3 CH5 13 CA 12 CD 6 CC 5 CB CH7 CH6 7 CH35 4 1 PL8 2 CH33 3 CH34 4 VCC 14 CH8 3 7 Q1, Q2, R13 AND R14 OPTIONAL. SEE TEXT 3 Q0 14 Q1 2 Q2 IC5 15 Q3 4028 1 Q4 6 Q5 Q6 7 VCC VCC PL3 7 14 E F 10 8 10 A 13 B 12 C 9  K VCC A D PPM C14 100pF SIN C15 100pF IC7c 4071 8 IC1 MV601 8 VSS 9 0/E OSC 6 X1 500kHz 7 4 R4 120k VDD DR 6 5 16 M/L C16 0.1 OA 3 R7 27k 5 RA RST C17 0.1 11 GND TP IVSS 14 13 OVSS 12 REG 4 2 R11 270  A LED1 RED 1 PL9 2 CH37 I/OA 1 2 I/OA 3 I/OB 4 I/OB IC11 8 4066 I/OC 9 I/OC 10 I/OD 11 I/OD 3 CH40 4 1PL10 2 CH39 3 CH38 4 7 Q1 R14 BC549 C 3.3k B E R13 3.3k B SW1b SW2a MOMENTARY 4 VCC 10 PR 9 12 Q CK IC6b 8 11 D Q CLR 13 MOMENTARY E SW1a LATCHED SW2b LATCHED C Q2 BC549 74HC74 VCC 14 2 3 5 Q CK IC6a 6 D Q CLR 1 7 A K A K B E C VIEWED FROM BELOW ADJ OUT IN May 1994  67 L1 3-6V Q1 47  A K 2x100pF 47k 10k SW-DIP4 IC1 MV500 SW-DIP8 X1 1 SW13 Fig.3: the component overlay for the transmitter. Note that you could substitute a 32-way keypad for the DIP switches if you wish. This would make coding much easier. Fig.4 at right shows the full size artwork for the receiver board. TABLE 1 Sw 1-8 Sw 9-12 Sw13 PL1,2 Channel Sw13 PL1,2 Channel 00000001 0001 out Pos 1 Ch1 in Pos 5 Ch33 00000001 0010 out Pos 1 Ch2 in Pos 5 Ch34 00000001 0100 out Pos 1 Ch3 in Pos 5 Ch35 00000001 1000 out Pos 1 Ch4 in Pos 5 Ch36 00000010 0001 out Pos 1 Ch5 in Pos 5 Ch37 00000010 0010 out Pos 1 Ch6 in Pos 5 Ch38 00000010 0100 out Pos 1 Ch7 in Pos 5 Ch39 00000010 1000 out Pos 1 Ch8 in Pos 5 Ch40 00000100 0001 out Pos 2 Ch9 in Pos 6 Ch41 00000100 0010 out Pos 2 Ch10 in Pos 6 Ch42 00000100 0100 out Pos 2 Ch11 in Pos 6 Ch43 00000100 1000 out Pos 2 Ch12 in Pos 6 Ch44 00001000 0001 out Pos 2 Ch13 in Pos 6 Ch45 00001000 0010 out Pos 2 Ch14 in Pos 6 Ch46 00001000 0100 out Pos 2 Ch15 in Pos 6 Ch47 00001000 1000 out Pos 2 Ch16 in Pos 6 Ch48 00010000 0001 out Pos 3 Ch17 in Pos 7 Ch49 00010000 0010 out Pos 3 Ch18 in Pos 7 Ch50 00010000 0100 out Pos 3 Ch19 in Pos 7 Ch51 00010000 1000 out Pos 3 Ch20 in Pos 7 Ch52 00100000 0001 out Pos 3 Ch21 in Pos 7 Ch53 00100000 0010 out Pos 3 Ch22 in Pos 7 Ch54 00100000 0100 out Pos 3 Ch23 in Pos 7 Ch55 00100000 1000 out Pos 3 Ch24 in Pos 7 Ch56 01000000 0001 out Pos 4 Ch25 in Pos 8 Ch57 01000000 0010 out Pos 4 Ch26 in Pos 8 Ch58 01000000 0100 out Pos 4 Ch27 in Pos 8 Ch59 01000000 1000 out Pos 4 Ch28 in Pos 8 Ch60 10000000 0001 out Pos 4 Ch29 in Pos 8 Ch61 10000000 0010 out Pos 4 Ch30 in Pos 8 Ch62 10000000 0100 out Pos 4 Ch31 in Pos 8 Ch63 10000000 1000 out Pos 4 Ch32 in Pos 8 Ch64 68  Silicon Chip small components first, leaving the MV500 IC till last. Watch the polarity of the IC, the transistor and infrared LED. Next, assemble the receiver. This is built on a board measuring 86 x 80mm and coded 15105941. Before you begin any soldering, check the board thoroughly for any shorts or breaks in the copper tracks. These should be repaired with a small artwork knife or a touch of the soldering iron where appropriate. If fitting the unit internally in a piece of audio equip­ment, you will need to look for a place to install the board and the infrared LED. You will also require a suitable relay which must be installed inside the equipment if you intend it to switch 240V AC. Naturally, you must follow standard wiring practice and take care with the isolation of all 240V AC wiring. You will need to make a number of choices during construc­tion and they are as follows: (1). Are you powering the receiver circuit from a regulated voltage of between 5V and 6.8V? If so, you will not need the LM317, R8 and R9. (2). Do you need to operate relays? If so, you are advised to delete IC11 and fit transistors Q1, Q2, R14 and R13. This enables you to drive two relays up to 16V and 75mA. Note that a reverse-biased diode should be connected across each relay coil. (3). If you are driving relays in the latched mode, do you want the transistor normally on or normally off? Using the solder links on the copper side of the board, short pin 8 of IC6b to pin 2 of SW2a for normally on and pin 9 of IC6b to pin 2 of SW2a for normally off (Q1); and pin 6 of IC6b to pin 2 of SW1a for normally on and pin 5 of IC6b to pin 2 of SW1a for normally off (Q2). Note: if you are using Q1 and Q2, it is advisable to con­nect any load to the unregulated positive voltage to avoid the need for a heatsink to be fitted to the LM317 regulator. With these decisions made, it is now a fairly straightfor­ ward matter of loading all the components onto the board, start­ing with small passive components and headers first and leaving the integrated circuits and other semiconductors till last. Take care with the polarity of semiconductors and electrolytic capacitors. Testing the transmitter There is not much to testing the 10uF .022 .0047 IC2 SL486 SW 2b 0.47 SW 1a 1 10k 1k X1 2x100pF 4.7uF +9-16V REG1 LM317 1M 1 IC3 74HC138 PL1/2 PL3 1 IC4 4028 IC9 4066 1k IC1 MV601 1 PL6 IC12 LM358 D1 1 1 IC6 74HC74 1 120k 4.7k IC8 4066 SW 1b 0.1 PL5 .0047 1 22uF .015 27k SW2a PL10 R13 Q2 M L IC5 4028 1Q1 R14 IC11 PL9 PL7 100pF 1 IRD1 1 0.15 GND TP IC10 4066 47  68uF 6.8uF PL8 240  0.1 100k transmitter until you have built the receiver circuitry. One simple go/ no-go test is to see if your intelligent remote control indicates that it has learnt a code when the two units are placed together. Another simple test is to replace the infrared LED with a visible LED and note if it is pulsing. Alternatively, use a logic probe on the collector of Q1. To set up a code, the transmitter must have one switch of SW1-8 on and one switch of SW9-12 on (see Table 1). The receiver must be powered up and tested before it is installed in the device to be controlled. You will also need to set the two shorting links on PL1 and PL2 to select the addresses so that you can set the transmitter code accordingly (again, see Table 1). Power up the receiver board and check that the current drain is around 30mA (with no relays operating). Select a code for a channel you would like to test and bring the transmitter close to the receiver’s infrared detector (IRD1). The Data Ready LED should light, until the transmitter is turned off. With a multimeter set to “ohms”, check the channel you have selected with the transmitter. Ensure that the transmitter is on and the Data Ready LED is on while checking the resistance between the two pins for the channel. When the channel is selected, the resistance should be less than 200Ω. If all is well, continue testing all channels. 1 PL4 IC7 4071 A 270  IC11 NOT FITTED WHEN Q1, Q2, R13 AND R14 ARE USED LINK ON REG1 FITTED WHEN OPERATING ON LESS THAN 6.5V LED1 Fig.5: the component overlay for the 16 channel receiver board. Take note of the settings in Table 1 when wiring up the board & refer to the text to select the pin header options. Troubleshooting If you have followed the testing procedure correctly and things are not working, here are some checks to make: (1). If the Data Ready LED does not light when the transmitter is sending a valid code, check that the supply voltage is correct for IC1 and IC2. Are you testing under direct sunlight or under very bright lights? Shade the infrared detector (IRD1) or bring the transmitter closer to the receiver. (2). If the Data Ready LED lights but the channels are not switching, try sending three or four different codes with the transmitter to see if it is an isolated problem. Check that PL1 and PL2 are set correctly; check the supply rails on ICs 3, 4 & 5; check the binary code from IC1 on pins 3, 11, 12, 13, 14 & 15; and check that it is the code that you expected the transmitter to send. Check that the Fig.6: full size artwork for the transmitter board. correct output for this code is enabled on IC3 (pins 7-15, excluding pin 8). Finally, check that the appropriate output of IC4 or IC5 is high to select its particular bilateral switch. (3). If channels 39 or 40 don’t latch or transistors Q1 or Q2 don’t turn on, check the solder straps on the copper side of the board associated with IC6. Check that SW1 and SW2 have short­ ing links in either the momentary or latched positions, as appropriate. SC May 1994  69