Apple Remote Control for Buffalo II DAC
I have programmed for the Apple Aluminum Remote Control to control the volume in the Buffalo II DAC. I think this is the nicest remote control available for the application. It can be purchased at any Apple Store for $20 or so.
You can find the code here: Code for Buffalo II vB05
Note: for the latest code, check the “CODE” tab. The Apple remote code is part of the code that controls the DAC
For the manner I used to read the signal pulses from the remote, it required a modification to the Arduino pulseIn library. I defined a replacement pulseIn function with an additional time out parameter. This is explained in the code and also in the Arduino forums. It is further explained here.
WHICH IR RECEIVER?
You can probably use any IR receiver you can find. I had scavenged some IR receivers from old electronics and they work but are too sensitive to ambient light, so I get a lot of spurious signals. The code will only accept valid sequences, so spurious signals will be ignored. However it is not a good idea to have the processor continually process spurious signals.
38 Mhz, AGC4 type
If you are buying one, get one that is designed for remote control and with a frequency of 38 KHz because the NEC protocol that is used by the Apple Remote is designed for 38 KHz operation. Further, the “AGC4″ type is best for the NEC protocol. According to Vishay documentation, “AGC4 is optimized for most common remote control standard applications in very noisy environments (including dimmed LCD backlightings)”.
It is also worthwhile to note that the pin assignment for IR receivers is not standardized so you need to know the exact pin assignment of the receiver. If you need a recommendation, the Vishay TSOP32438 [datasheet] is a good device. The TSOP32838 will also work. The only difference is that it is “not designed for noisy environments”. If you do a search in Digikey or Mouser and confine the results to 38 MHz you will find many candidates.
Below is the connection diagram for the IR receiver
- Disturbance Sources: Describes sources for noise and also prescribes a circuit to filter noise from the power supply
- Choosing an IR Receiver based on AGC Type: Describes what AGC (Automatic Gain Control) means
- Review of Apple Aluminum Remote Controller: Good overall review and also explains why some of the IR codes from the remote contain double commands
I like this picture I scraped from Soomal