DSP-ADAU1467

ModulosDSP — ESP32-S3 WiFi Bridge for ADAU14xx DSP

An Arduino sketch for the Waveshare ESP32-S3 Zero that provides a WiFi interface to Analog Devices ADAU1401/1701 DSP chips:

• SigmaTCP bridge (port 8086) — lets SigmaStudio connect wirelessly to a physical DSP over I²C
• HTTP EEPROM uploader (port 80) — flash DSP firmware binaries to a 24C256 EEPROM from a browser

This sketch runs on the companion MSD ADAU14-1701 Adapter PCB.

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Hardware

Component	Part	Notes
Microcontroller	Waveshare ESP32-S3 Zero	Onboard WS2812 NeoPixel on GPIO 21
DSP	ADAU1401 / ADAU1701	I²C address 0x68 (7-bit: 0x34)
EEPROM	24C256 (32 KB)	I²C address 0xA0 (7-bit: 0x50)
Display	20×4 hd44780 I²C LCD	Boot status and IP address

Pin Assignments

Signal	GPIO
I²C SDA	13
I²C SCL	12
Status LED (NeoPixel)	21 (built-in)

The DSP, EEPROM, and LCD all share the same I²C bus at 400 kHz.

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Arduino Libraries Required

Install via Sketch → Include Library → Manage Libraries:

Library	Purpose
WiFi	ESP32 WiFi (built-in with ESP32 core)
WebServer	HTTP server (built-in)
Wire	I²C master (built-in)
LittleFS	Embedded filesystem for web assets (built-in)
Adafruit NeoPixel	WS2812 status LED
hd44780	I²C LCD driver

Board: select ESP32S3 Dev Module (or Waveshare ESP32-S3 Zero if your board package includes it) via the ESP32 Arduino core.

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Configuration

Before flashing, edit ModulosDSP_101.ino and update the WiFi credentials:

const char* ssid     = "your_network_ssid";
const char* password = "your_network_password";

There is no runtime configuration — credentials are compiled in.

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Status LED

The onboard NeoPixel (GPIO 21) shows current activity at a glance:

Color	Meaning
Off	Idle — no TCP client connected
Green	DSP write in progress (SigmaTCP)
Blue	DSP read in progress (SigmaTCP)
Yellow	EEPROM write via SigmaTCP
Magenta	EEPROM upload via HTTP
Red flash	Error (I²C failure, buffer overflow, bad packet)

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Using with SigmaStudio

1. Power on the board. The LCD displays the assigned IP address; Serial (115200 baud) also prints it.
2. In SigmaStudio, open Settings → Hardware Configuration.
3. Add a USBi interface and switch the connection type to SigmaTCP.
4. Enter the ESP32's IP address and port 8086.
5. Click Link → Compile Download — SigmaStudio pushes firmware to the DSP wirelessly.

The bridge handles both direct writes and safeload writes (glitch-free atomic parameter updates on a live DSP).

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EEPROM Uploader (Web UI)

Navigate to http://<ESP32-IP>/ in any browser:

1. Click Choose File and select a SigmaStudio-exported binary.
2. Optionally tick Verify (CRC32) to read back and confirm the write.
3. Click Upload — the Magenta LED pulses during the write.

The 24C256 holds 32 KB. The DSP reads this EEPROM at power-up via its SELFBOOT pin, allowing standalone operation without the ESP32 actively present.

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How It Works

SigmaTCP Bridge

SigmaTCP is the protocol used by Analog Devices' SigmaStudio to talk to hardware like the USBi programmer. This sketch implements the server side over TCP/WiFi and forwards all register traffic to the DSP or EEPROM via I²C.

WRITE (opcode 0x09):

• 10-byte header: command, safeload flag, placement, totalLen, chipAddr, dataLen, startAddress
• Payload forwarded to DSP or EEPROM via I²C
• 4-byte ACK sent back: {0x09, 0x00, 0x04, status}

READ (opcode 0x0A):

• 8-byte header: command, totalLen, chipAddr, dataLen, startAddress
• I²C data read in 32-byte chunks
• 6-byte response header (0x0B, totalLen_hi, totalLen_lo, status, dataLen_hi, dataLen_lo) + payload sent back
• On I²C failure, zeros are sent rather than dropping the connection (allows SigmaStudio to probe an unresponsive DSP)

Safeload:
When the safeload flag is set, parameters are queued into the DSP's 5 hardware safeload slots and committed atomically by writing 0x003C to the Core Register. This avoids audio clicks when updating parameters on a running DSP.

The TCP receive loop drains all available bytes into a 50 KB buffer every iteration (keeping the TCP receive window open), then processes complete packets from the buffer. This correctly handles large program downloads that span multiple TCP segments.

EEPROM Writes

Writes are chunked to ≤28 bytes, aligned to 64-byte page boundaries. After each chunk, the firmware polls the EEPROM for ACK (up to 120 ms) to wait for its internal write cycle before continuing.

Fixed-Point Format

The ADAU1401 uses 5.23 fixed-point for parameter RAM (4 bytes per word). Safeload registers add a leading 0x00 padding byte, making them 5 bytes. The DataConversion class handles conversion from float, int32_t, and other C types.

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File Structure

ModulosDSP_101/
├── ModulosDSP_101.ino   Main sketch: WiFi, TCP/HTTP servers, I²C bridge
├── DSPWriter.h          DSP register write interface and address map
├── DSPWriter.cpp        I²C write and safeload implementations
├── DataConversion.h     5.23 fixed-point conversion declarations
├── DataConversion.cpp   Fixed-point conversion implementations
└── index_html.h         Embedded HTML for the EEPROM upload web UI

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ADAU1401 Address Map

Region	Address Range	I²C bytes per register
Parameter RAM	0x0000–0x03FF	4
Program RAM	0x0400–0x07FF	5
Interface Registers 0–7	0x0800–0x0807	1
GPIO Register	0x0808	1
ADC 0–3 (read-only)	0x0809–0x080C	1
Safeload Data 0–4	0x0810–0x0814	5
Safeload Address 0–4	0x0815–0x0819	2
Core Register	0x081C	2 (R0 reset)
MpCfg 0–1	0x0820–0x0821	1
Analog Power Down	0x0822	1
Analog Interface 0	0x0824	1

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Version History

Version	Notes
1.3.1	Current stable. chipAddr 0x01 fix on clean v1.3.0 base
1.3.0	Fixed 6-byte SigmaTCP read response header; added write ACK; I²C read failure returns zeros
1.2.0	Added WS2812 NeoPixel status LED
1.1.0	Buffer overflow checks, explicit chipAddr lookup, safeload dataLen validation
1.4.0	(Changelog entry) Block-read TCP receive with per-packet timeout for large program downloads

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References

• SigmaStudio TCP interface for ESP32 — Analog Devices forum
• roTDSP — ADAU1401 carrier board
• SigmaDSP Arduino library (MCUdude)
• Elektor AudioDSP — ESP32 + ADAU1701
• How to program an Analog Devices DSP