IR2SLink

Arduino sketch allowing translation of IR sequeces to Sony S-Link Control-A1 commands for Sony audio devices

Arduino infrared input driver for the Sony S-Link Control-A1 interface, implementing a general purpose infrared interface to remotely drive Sony audio consumer devices connected through the Sony S-Link bus-system.

Installation

Create a new folder called "IR2SLink" in your Arduino sketchbook folder. Place IR2SLink.ino in the "IR2SLink" folder.

This software needs the following libraries:

Check https://github.com/Ircama/AtTinyTestIR to monitor infrared sequences through an ATTINY85.

Check also this note: https://gist.github.com/Ircama/22707e938e9c8f169d9fe187797a2a2c

Description

This code allows receiving IR sequeces from a generic IR remote and drive a consumer audio Sony device via Sony S-Link Control-A1 input interface; it also includes trivial monitoring capabilities for IR codes and for the S-Link interface, to test and dump received sequences, which can be used for code customization.

In standard operation, the code is targeted to the ATtiny85 microcontroller (e.g. Digispark Digistump ATtiny85). As the ATtiny85 USB interface does not allow confortable monitoring and debugging features, testing IR codes or dumping the S-Link interface can be achieved through an ATmega328P micro (e.g., Arduino Nano). (Also, a separate program allows raw IR code monitorig with the ATtiny85.)

The code uses the IRemote library (http://z3t0.github.io/Arduino-IRremote) to read IR keys and Sony_SLink to drive the S-Link interface. IRemote should be appropriately customized by editing IRremote.h and disabling all the IR protocols except the needed one (keeping just the reception part, not the transmission which is not used by this program); this is in order to reduce the code size to the minimum so that it can fit the very limited ATtiny85 space.

The code sets the ATtiny85 to the sleep mode and keeps the micro in quiescent state for most of the time, in order to save power when the IR receiver does not detect data (total consumption < 1mA including IR receiver); a timer limits the operation time of the mocrocontroller just to process infrared sequences (tyical consumption of about 10 mA @ 3.2 V during IR reception and for MILLIS_TO_SLEEP milliseconds).

The Digispark Digistump ATtiny85 device has to be modified as follows to save power:

remove the power led;
to supply power, either the 12.6V internal rectifier of the Sony device (e.g., close to the secondary AC transformer) or the 5.6V logic circuit rail can be used; if supplying power with 5.6V, remove the linear voltage regulator of the Digispark (LM78L05 has a quiescent current of about 2.5 to 3 milliamperes) and substitute it with diodes in series (or zener) to reduce the voltage to about 3.2V (this will be the most effective way to reduce quiescent current to the minimum);
enable D- pull-up only when the USB is connected (this can be achieved by moving the pull-up resistor connection to take the positive voltage directly from the USB +5V and not from the Digispark internal +5V, which is after the schottky diode separating USB from the internal +5V; this configuration reduces power consumption by avoiding current flow throgh the D- zener during normal operation, preserving the D- pull-up when USB is connected, which is anyway needed by the USB hw interface);
use a low power infrared receiver (e.g., TSOP4838 connected to P0);
connect S-Link to P2
flash the Digispark bootloader with the latest Micronucleus V2.03 version (which has a significantly compact size) and with "#define ENTRYMODE ENTRY_EXT_RESET" in micronucleus-master/firmware/configuration/t85_default/bootloaderconfig.h
Use the Digispark reset pin to enable the firmware upload (setting ENTRYMODE to ENTRY_EXT_RESET avoids to hang the Digispark if D- is not pulled-up); a microswitch between D5 and ground is appropriate, also pulling up D5 to VCC with a 22kohm resistor.

How to use

connect the Digispark Digistump ATtiny85 to the S-Link interface of the Sony device
provide power supply from the Sony device (or through external unit, or battery)
the mapping of IR sequences with related S-Link commands has to be preconfigured (code customization is needed for this)
Pressing a key on the IR remote will control the Sony device

How to customize this program

edit IRremote.h and configure the needed protocols (e.g, just to read SAMSUNG codes)
select the related "results.decode_type" (e.g, decode SAMSUNG)
within the code, define the S-Link commands to be invoked by each IR key

Notes for this program