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DSP Musicolour: adding a remote control With a small and low-cost add-on PC board, the DSP Musicolour can be operated via an infrared remote control – very handy if you want to use it in hard-to-reach places. Part Four – by Mauro Grassi R emote control adds so much more convenience! After completing the DSP Musicolour design (as published in the June, July and August issues) we looked at the possibility of adding infrared remote control. It turned out to be really simple – so here we describe how to build a simple remote control receiver PC board to allow the DSP Musicolour to be operated via a remote control which uses RC5 codes – the vast majority – or a universal remote control. The DSP Musicolour firmware contains the decoding functions. The schematic for the remote control receiver board is shown overleaf It contains little more than an infra72  Silicon Chip red receiver module that amplifies and demodulates the remote control signal. The signal is then decoded by the firmware. Apart from the IDC header which connects the Remote Control PC board back to the main board, there are only three other components: a 47mF capacitor to bypass the supply rail (taken from the DSP Musicolour’s 5V MUSICOLOUR - THE MOVIE! It’s quite hard to put into words just how sensational the DSP Musicolour lightshow really is . . . so you’ll be able to see it! Around the time this issue appears, we hope to have ready a short demonstration movie which can be accessed via the SILICON CHIP website. rail) and a 100W resistor to limit the current and further isolate the infrared module from the supply rail. Finally, there is a 330W resistor. As the RF6 pin of the microcontroller (IC1) can function as an output as well as input, this resistor is used on the output of the module to limit the current into the data output of the infrared receiver module. Construction This is a simple board that should take a matter of minutes to build. Simply refer to the component overlay and the accompanying photograph. Begin by installing the resistors. There are only two of them so it’s going siliconchip.com.au to be particularly difficult to mix them up. (Hint: the 100W has bands which start with brown and black while the 330W has two orange bands!) But if in doubt, check them with a DMM. Next is the 47mF capacitor which, being polarised, must be oriented correctly as shown in the component overlay. To make the PC board as low in height as possible, it must be “laid over” 90° so that it lies along the board. Therefore you will need to bend both leads down 90° before soldering it in. Then solder in the infrared receiver module, allowing around 7mm of lead. Similarly to the electrolytic, it mounts so that it lies flush with (ie, parallel with) the PC board surface, as shown in the enlarged photo at right. The last thing to solder in is the 10-way IDC header. The remote control board connects to the main board via a 10-way ribbon cable, from CON1 on the remote control board to CON3 on the main board. We explained how to make a 26-way ribbon cable connecting the main board to the display board in the July 2008 issue (page 26 under Ribbon Cable Assembly). The 10-way ribbon cable used to connect the remote control board is made in the same way. The completed remote control PC board sits between the red acrylic front panel and the display board, as photographed below. It actually sits Here’s the DSP Musicolour Infrared Controller Receiver, shown much larger than life size for clarity. Note how both the infrared detector itself and the electrolytic smoothing capacitor are both “laid over” to give minimum height to the Receiver and allow it to be sandwiched between the red acrylic front panel and the display PC board. on top of some resistors between LED array 3 and two 74HC595 ICs. It is secured in place with a selfadhesive foam pad or two (available at any newsagent or stationer). Being a couple of millimetres thick, these pads have the added advantage of providing insulation between the remote control board and the components on the display board underneath. You will need to open the case to install it so you must first make absolutely certain that the IEC mains power lead is not plugged in. The ribbon cable connecting to the remote control PC board also helps locate the board – when its IDC con- nector is plugged in, the top edges of both the controller PC board and the display board are in alignment, with just enough room for the IDC cable to go over the top of the display board and wedge between the display board and case top. Once the board is connected, close the case and insert the screws which hold the two halves together, then (and only then) power up the DSP Musicolour. Don’t be tempted to take a short cut and leave the screws out! Defining the codes There are only nine remote control codes used to control the DSP Musi- Here’s where the add-on remote control receiver board fits, between the display and IC3 & 4. It’s held in place by an adhesive foam pad on its back, which also insulates it from the components underneath on the the display board. Inset at left is the board in situ, looking down. siliconchip.com.au September 2008  73 100Ω IRD1 5 8 47 µF 16V 3 λ 10 330Ω 1 Parts List – Remote Control for DSP Musicolour CON1 1 PC Board coded 10107083 measuring 24mm x 44mm 1 infrared remote control using RC5 code, at least nine buttons (see text) 9 2 4 Semiconductors 1 infrared receiver module (IRD1) (Jaycar ZD1952, Altronics Z1611) 2 Miscellaneous 1 10-way right-angled IDC header (Jaycar PP1118, Altronics P5060) 1 10-way ribbon cable, approx 20cm long 2 10-way IDC cable line sockets (Jaycar PS0984, Altronics P5310) 2 self-adhesive foam pads (adhesive both sides) 3 SC 2008 IRD1 DSP MUSICOLOUR REMOTE CONTROL RECEIVER 1 3 If you can find a simpler circuit, good luck! The Infrared Detector both receives and decodes the signal from the Remote Control. The microcontroller in the DSP Musicolour does all the hard work! colour. These must be defined at least once, using the front panel buttons, before operating the DSP Musicolour with a remote control. First, you must make sure that your remote control is an RC5-compliant remote control. RC5 is a protocol designed by Philips but not all remote controls in use today actually work with this protocol. Other protocols will not work with this decoder, so you should make sure that you have an RC5 remote control. If you are using a universal remote, there is a good chance of it working if you set it to a Philips appliance (eg, a TV set or VCR). Go to SYSTEM>Remote Control and follow the prompts. You will be asked to define each of the nine keys in turn, keys 1 to 7 correspond to the buttons on the front panel in the following order: UP, SET, DOWN, CH1, CH2, CH3 and CH4. The corresponding button LED will light and you should press the key on your remote control that you want to use to emulate that key on the front panel. Naturally, you would use the channel up and channel down buttons for up and (RIBBON CABLE TO MAIN BOARD) 1 2 CON1 CS 3 8 0 7 0 1 0 1 9 10 47 µF 100Ω 330Ω + IRD1 BEND BOTH OVER 90 o Here the Infrared Receiver PC board and component overlay are shown life size. And there’s not much to it! Watch the polarity on the 47mF electrolytic capacitor and note which way around the pins go on the infrared detector (actually, if you get this back to front, the lens will face down into the PC board – a pretty good indication that it’s not quite right!). 74  Silicon Chip Capacitors 1 47mF 16V electrolytic, PC board mounting Resistors (0.25W, 1%) 1 330W 1 100W down – it makes it easier to remember. After the seven buttons on the front panel, the next two buttons are used to emulate the SELECT potentiometer and require you to enter a key for “+” and “-” to emulate the analog potentiometer. Again, you would normally define these two buttons as Volume UP and Volume DOWN on your remote control. Even universal (programmable) remote controls normally have channel up/down and volume up/down labeled. To test that the DSP Musicolour is correctly understanding the remote control signal you can go to the SYSTEM>RC5 Echo submenu. This will display (in hexadecimal) the 12-bit code received by the Musicolour. You should see the numbers displayed as you send commands to the Musicolour using your remote control. We have tested the DSP Musicolour with the Digitech AR-1725 (Jaycar AR-1725) universal remote shown earlier, and we set it up as follows (most other universal remotes will work too). We had intended to use the much cheaper Select1 remote control (Jaycar AR1703) but found it only had seven buttons, so was not suitable. However, if your household is typical, you probably have a growing collection of once-used infrared remote controls. One of these may be suitable if it uses the Philips (RC5) protocol. If you don’t know and can find the code sheet for it, program it for any Philips device and try it out. You can’t do any harm, even if it is wrong. It simply won’t work! Of course, it may be that the batteries are flat . . . If it doesn’t have a visible LED tell-tale, the easiest way to check Here’s the display for programming your remote control – as each LED lights, you press the appropriate button on your remote control. siliconchip.com.au Button on Front Panel to Emulate Press this key on remote control when prompted AUTO/UP “Volume UP” button SET/OK “OK” button USER/DOWN “Volume DOWN” button CH1/A “1” button CH2/B “2” button CH3/C “3” button CH4/D “4” button Potentiometer + control (*) “Channel UP” button Potentiometer – control (*) “Channel DOWN” button Table 1: this shows a suggested remote control code definition sequence using a Digitech AR-1725 universal remote control (or any RC5 remote control with 9 buttons or more) and the optional remote control decoder PC board. Note (*): this control is not a button on the front panel, but is used to emulate the SELECT potentiometer on the front panel using the remote control. that an infrared remote control is actually outputting infrared is to view it through just about any digital or video camera. Most are sensitive to infrared and you should see bright white (or sometimes green) flashes in the viewfinder when aimed at the remote control. If you are using the Digitech remote control, set it for the VCR 115 code (this is the code for a Philips VCR, although many other Philips codes should work too). Go to the SYSTEM>Remote Control submenu. There you will see whether the remote control has been defined. If it indicates that it has not been defined, you may press SET to define the remote control codes. You will be asked for confirmation and if you proceed, you will be able to define the remote control codes to suit your remote. You’ll be prompted to define each of the nine keys in turn. You can refer to Table 1 giving a suggested definition (you can of course choose another sequence of keys to define if you wish). Once you’ve defined the remote control codes, the DSP Musicolour will respond to both the buttons on the front panel and to the remote control keys you have defined. So you can operate the DSP Musicolour with either. Finally, an errata: on the Display PC board component overlay published on page 26 of the July issue, the ICs labelled IC1, IC2, IC3 and IC4 should be labelled IC3, IC4, IC5 and IC6 respectively to agree with the circuit diagram published in June. The actual type numbers of those ICs are all correct as published. SC This screen is for checking the remote control: it displays the received codes from your remote control as decoded by the firmware. siliconchip.com.au September 2008  75