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StageConnect

This repository contains an Arduino-Library to create a StageConnect device (subordinated node-device as well as controlling main-device) using AnalogDevices AD242x-ICs like the AD2428.

StageConnect is based on the automotive A²B and is used to connect the Behringer WING to the Midas DP48, for instance. Analog Devices A²B audio bus is used as the technology basis and uses simple XLR connectors between two devices to transmit 32 channels of uncompressed 48kHz 32bit audio.

A StageConnect/A2B main-device uses a virtual I2C-connection through the A2B-link that is routed via the AD242x-IC to the Arduino microcontroller.

Usage

The library supports both roles on the A2B link:

  • Subordinate node (isMaster = false): the Arduino is an I2C slave of the AD242x. The A2B main-device (e.g. a Behringer WING) discovers it over the A2B link and reads/writes the StageConnect register map through the AD242x.
  • Main / controlling device (isMaster = true): the Arduino is the I2C master of the AD242x. The chip is configured as A2B master and runs the discovery round for any subordinated devices connected via XLR/CAT cable.

Subordinate node

Include the main-library as well as the I2C-Wrapper-Class, instantiate both classes and setup the Wire-library:

#include <StageConnect.h>
#include <ci2c_com.h>

Ci2c_com i2c_com;
StageConnect stageConnect(false, 1, 0xD0, &i2c_com);

void I2C_RxHandler(int numBytes) {...}
void I2C_TxHandler(void) {...}

void setup() {
    Wire.begin(0x3D);
	Wire.onReceive(I2C_RxHandler);
	Wire.onRequest(I2C_TxHandler);
}

stageConnect.update() should be then called every 100ms.

See examples/SimpleSlave to learn how to use the callbacks and the mailbox-system to receive channel-names from the host-device.

Main / controlling device

#include <StageConnect.h>
#include <ci2c_com.h>

Ci2c_com i2c_com;
StageConnect stageConnect(true, 1, 0x68, &i2c_com); // isMaster = true

void setup() {
    Wire.begin();                // Arduino acts as I2C master
    stageConnect.config(0x80, 0x0001, 16, 16,
                        AD242X_I2SGCFG_EARLY | AD242X_I2SGCFG_TDM16, 32);
}

Call stageConnect.update() every 100ms. Internally it runs the A2B discovery round and keeps the chain alive. Use stageConnect.master() to access the Csc_master interface for sending/receiving messages, querying the number of discovered nodes, reading channel allocations, etc.

See examples/SimpleMaster for a complete sketch.

For electrical connection have a look at the following picture showing the connection with the AD2428MINI evaluation board: alt text

Technical information

Analog Devices suggests cable-length of up to 15 meters, while Behringer allows longer cables. The filter-network of the AD242x-chips is quite tricky and needs caution on adjusting the hardware-parameters. Use the schematics of the AD2428MINI as a reference.

Read the files in the folder "Documentation" for more information about the configuration-options and technical details regarding the brand- and product-ID as well as the specific commands for the mailbox-system.

Please use brand-IDs above 0x80 to prevent interference with other products.

Credits

Many thanks to MusicTribe/Behringer for sharing detailed information about the used protocol and for the permission to share the code publicly.