S-Link 40khz IR Demodulator

Why and what is this?

This project adds an IR 40Khz demodulator that attaches to the S-Link port on my STR-DA90ESG amp. This allows any programmed remote to send normal 40Khz signals across the room and control most basic functions of the amp. Because this is a standard IR signal, any learning remote can learn these codes from a correctly programmed transmitter. This external device does not require that you modify your Sony product in any way, or require a second Sony product to attach to.

Why do this? Because the VisionTouch units (model numbers ending in G) use a 455Khz IR remote. There is no learning remote, or pre-programmed remote on the market today (end of 1999) that can control the VisionTouch units directly (including ones made by Sony). The Philips Pronto can send 455Khz commands, but can not learn them. To date there is no VisionTouch CCF to solve this problem (I'm working on one).

How it works:

This is not a basic primer on IR functionality. Sony S-Link uses a simple repeatable binary command code (no parity). This code has 5 or more bits depending on the age of the command (current commands have 20 or more bits). Sony first started using this simple command in two forms, 40Khz modulated IR signals and direct TTL signals on the Control-S ports. Sony later used two protocols, one for IR commands and one for TTL bus commands (Control-S/Control-A/S-Link). This IR demodulator just converts binary S-Link commands sent by the remote into TTL signals injected into the S-Link bus. The Sony amp just thinks there is a device (like a DVD player) sending commands to it...like, power on please and select DVD video input while you are at it...Because newer components were not meant to be user controlled from a remote by the S-Link port most of the commands are discrete. For example there is 'power on' and 'power off' as separate commands, but no simple 'power' command (to turn on or off the unit) ...or at least I have not found them yet....(see commands section)

Stuff you need:

Parts from Radio Shack, or just sitting around the house: Cost about $23 to $27 depending on if you need the patch cable. (I used an 18" one I had siting around)
The power adapter should be 5V, but the 4.5V version works ok. It does need to be regulated AND filtered, remember you are ataching this to an expensive item! Regulation is required so the TTL signal is the correct voltage and filtering keeps the signal clean so your equipment is not confused.

Tools you need:

Construction:

Pronto Programming information:

S-Link Commands for my STR-DA90ESG Amp