michaeladams.org / Electronics
Irda Remote
Irda Remote
Hacking the KS-959 USB-IRDA adapter to something a little more standard.

This is a pretty basic Irda module I picked up off TradeMe for $10. It probably works just fine, but it doesn't work in WinLirc, which means I can't use it for what I want to do, which is remote control my camera.

Cracking it open, I found the following very basic circuit. Gotta love all-in-one USB ASICs, I spose. Unfortunately it uses a proprietry USB protocol, so isn't supported under Linux.

Which really only leaves me with the option of replacing its guts with a Texas Instruments TUSB3410 USB USART. This little beasty can handle RS232, RS485 and Irda. All it requires is a simple I2C EEPROM to store configuration data (and optionally the USB code; other option is to download it from the host upon instantation.

Pinout of Irda module
This is the Irda module present on the board.

From what I can tell, this is the pinout:

  1. (right-most pin in picture above) — connected to 33 ohm SMT resistor, controls LED anode current
  2. NC — LED cathode, leave open
  3. TXD
  4. RXD
  5. GND — shutdown, active high
  6. VCC (+5 VUSB)
  7. GND — sensitivity control. Pull high to increase sensitivity of device
  8. GND — system ground

This is similar to the Vishay TFDU4100, and indeed in faint letters on the top of the device are the numbers "4100 001" suggesting this is the same device. The datasheet for the TFDU4100 is available from Farnell.