SGTL5000 needs MCLK to be active before it'll talk I2C

[SmittyHalibut]

Problem Description

I'm trying to get an I2SCodecStream working with an SGTL5000 CODEC, and all I2C comms are failing without getting ACKs.

Probing SDA, SCL, and MCLK with my scope, I'm seeing that the very first I2C transaction is not getting ACK'd, and it all goes down hill from there. MCLK is idle, not clocking.

Page 11 of the SGTL5000 datasheet https://www.nxp.com.cn/docs/en/data-sheet/SGTL5000.pdf shows that MCLK needs to be clocking before the chip will respond:

Is there a way to get AudioDriver/AudioTools to turn on MCLK early in the process, before trying to configure the CODEC over I2C?

Device Description

It's a custom board. It's an RP2040 and an SGTL5000.

Relevant bits of the schematic:

Sketch

Relevant bits:


// Pin assignments, if it matters. Not sure it does, but here ya are.
const static uint8_t PIN_I2C_SDA = 12;
const static uint8_t PIN_I2C_SCL = 13;
const static uint8_t PIN_I2S_DIN = 17;
const static uint8_t PIN_I2S_DOUT = 18;
const static uint8_t PIN_I2S_BCLK = 19;
const static uint8_t PIN_I2S_LRCLK = 20;
const static uint8_t PIN_I2S_MCLK = 21;

AudioInfo info(44100, 2, 16);

// Destination: I2S
DriverDeviceInfo pins_sgtl5000;
AudioDriverSGTL5000Class sgtl5000;
AudioBoard board(sgtl5000, pins_sgtl5000);
I2SCodecStream out(board);

bool started;

void setup() {
    Serial.begin(115200);
    started = false;

    AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Info);

    Wire.setSDA(PIN_I2C_SDA);
    Wire.setSCL(PIN_I2C_SCL);

    Wire.begin();
}

void beginAudio() {
    pins_sgtl5000.addI2C(PinFunction::CODEC, PIN_I2C_SCL, PIN_I2C_SDA);
    pins_sgtl5000.addI2S(PinFunction::CODEC, PIN_I2S_MCLK, PIN_I2S_BCLK, PIN_I2S_LRCLK, PIN_I2S_DOUT, PIN_I2S_DIN);
    pins_sgtl5000.begin();

    board.begin();

    auto i2s_config = out.defaultConfig();
    i2s_config.copyFrom(info);
    out.begin(i2s_config);
}

uint16_t readReg(SGTL5000::Reg reg) {
    Wire.beginTransmission(SGTL5000_ADDR);
    Wire.write((uint16_t)reg >> 8);
    Wire.write((uint16_t)reg & 0xFF);
    Wire.endTransmission(false);

    Wire.requestFrom(SGTL5000_ADDR, 2);
    uint16_t ret_val = (Wire.read() & 0xFF) << 8;
    ret_val |= (Wire.read() & 0xFF);
    return ret_val;
}


void loop() {
    // This waits for the serial port to connect and my terminal to be ready before it starts doing stuff.
    if (!started && Serial.available()) {
        beginAudio();
        started = true;
    }
    if (started) {
        Serial.println(readReg(SGTL5000::Reg::ChipId), 16);
    }
    delay(1000);
}


platformio.ini:

[env:pico]
; platform = raspberrypi
platform = https://github.com/maxgerhardt/platform-raspberrypi.git
board = pico
framework = arduino
board_build.core = earlephilhower
monitor_port = /dev/ttyACM*

build_flags = 
    -DAUDIO_TOOLS_LOG_LEVEL="Debug"

lib_deps = 
    git@github.com:pschatzmann/arduino-audio-tools.git
    git@github.com:pschatzmann/arduino-audio-driver.git


These are the relevant bits.  I removed a bunch of debugging output so the functional code is easier to read.

I THINK I'm following the procedure of a Stand Alone board:
https://github.com/pschatzmann/arduino-audio-driver/wiki/Stand%E2%80%90Alone:-Custom-Boards

One thing that is different between my code and the documentation is that I had to instantiate an `AudioDriverSGTL5000Class` object and pass that to the `board()` instantiator, where as all your documentation and shows passing the CLASS to the instantiator.  When I try to pass the class instead of an object, it tries to interpret the `DriverDeviceInfo` object (second parameter) as an `<error_type>` instead.  I can't even find where that instantiator is defined!  Passing the object matches with the instantiators that I CAN find, so I'm assuming your docs are a touch out of date on that one.

Other Steps to Reproduce

Running this code returns FFFF when reading the ChipID. The other debug output shows that endTransmission() is returning with error code 4, which says it's not getting an ACK.

I have I2C SDA and SCL, and I2S MCLK going into my o-scope. I can verify that there is no ACK after the address/write packet, or the immediately following address/read packet (since my code isn't error checking on the register address write.)

All the while, MCLK remains inactive, no clocking. And the SGTL5000 documentation says that MCLK needs to be live before trying to talk to it on I2C.

What is your development environment (with Arduino Core Version information)

• Linux: Ubuntu 24.04, up to date, literally updated this morning.
• VScode: 1.126.0 (Part of that update this morning. :-)
• PlatformIO: Core 6.1.19, Home 3.4.4
• Audio Tools hash: b90c162140a1674aabddca091c635bf8f9273d96
• Audio Driver hash: adf7d79

I have checked existing issues, discussions and online documentation

• I confirm I have checked existing issues, discussions and online documentation

[pschatzmann]

Did you run an Arduino I2C Port Scan to confirm the address ?

For testing, I suggest that you use and initialize a simple I2SStream first: this should get the I2S signalling started: define the pins via the I2SConfiguration.

    config.pin_bck = PIN_I2S_BCLK;
    config.pin_ws = PIN_I2S_LRCLK;
    config.pin_data = PIN_I2S_DOUT;
   //   config.pin_data_in = PIN_I2S_DIN; 
    config.pin_mck = PIN_I2S_MCLK; 

Since in this case you will be setting up I2S and I2C via the Arduino API you can simplify by using

AudioBoard board(sgtl5000, NoPins);

After that you can call your board.begin(); to setup the SGTL5000

If that is working we can discuss if the sequence of initialization in I2SCodecStream needs to be changed.

ps.

• I confirm that the static AudioDriverSGTL5000Class AudioDriverSGTL5000; was indeed missing. I added it and updated the documentation
• I suggest that you start with out.defaultConfig(TX_MODE). In the example above the ESP32 will be sending the audio data via gpio 18
• is the CTRL_MODE pin pulled low to activate i2c ?

[pschatzmann]

I was double checking with ChagGPT:

If a codec doesn't ACK on I²C, it is almost always because of one of these reasons instead:

RESET pin still asserted.
PDN/SHDN pin held low.
Wrong I²C address (many codecs have address-select pins).
Missing DVDD/IOVDD supply.
Power sequencing issue.
Chip in hardware control mode rather than software/I²C mode.

[SmittyHalibut]

Was away at Field Day all weekend, and catching back up yesterday. I'll dig into this today. But real quick response:

• I have not done a probe for the address yes, but there's only one option according to the documentation. I'll do the probe.
• I'll do what you suggest to get I2S started before calling board.begin().
• I'm using the 20-pin variant of the SGTL5000, there is no CTRL_MODE pin. It hard codes for I2C, and only the first I2C address.
• Similarly, there's no RESET, Power Down, or Shutdown pins.
• All supplies are ... supplied, and are correct. Verified with test meter.
• There is no hardware control mode, it's only I2C.

Power sequence is exactly what I think we are dealing with here.

Let me test by changing around the order of start-up, see if that helps. I'll get back to you.

[SmittyHalibut]

Ran the I2C scanner at https://learn.adafruit.com/scanning-i2c-addresses/arduino and it finds nothing on the bus.

SUCCESS!

Ok. The working code is:

    auto i2s_config = out.defaultConfig(TX_MODE);
    i2s_config.copyFrom(info);
    i2s_config.pin_bck = PIN_I2S_BCLK;
    i2s_config.pin_data = PIN_I2S_DOUT;
    i2s_config.pin_mck = PIN_I2S_MCLK;
    i2s_config.pin_ws = PIN_I2S_LRCLK;
    
    out.begin(i2s_config) || Serial.println("FAILED");

After doing that, I'm able to request the Chip ID register, and the chip responds to the I2C bus scan.

Again, the only thing that changed is that I'm starting the I2S config before trying to talk to the chip on I2C, which is backed up by documentation for the SGTL5000 chip (see above).

I haven't done it yet, but I assume setting up the board with NoPins will now do what I want. Assuming that works, then I have what I need for the immediate term. But this seems like something that should be covered by your library.

I'm happy to perform any tests you'd like me to, or whatever I can do to help.

[pschatzmann]

Should there be some delay() after starting i2s before running the codec configuration via i2c ?

[SmittyHalibut]

I started playing around with Pins and Boards, and couldn't get it to work. So I backed out to the same code that worked above, and ... its not working now. I have a suspicion that I have to wait until tomorrow to test (I have plans tonight.)

I saw the delay(400); in your SGTL5000 driver, so I added that after turning on I2S to my code as well.

[pschatzmann]

Did you try i2s_config.pin_data = PIN_I2S_DIN ? I think your data naming is from the view of the codec and not the ESP32;

[SmittyHalibut]

deleted I was wrong about it working again, let me collect more data, stand by.

[SmittyHalibut]

Here's my initialization code:

AudioInfo info(44100, 2, 16);
// Source: sine wave
SineWaveGenerator<int16_t> sineWave(16000);
GeneratedSoundStream<int16_t> usb_stream(sineWave);
//USBAudioStream usb_stream;

// Destination: I2S
DriverDeviceInfo pins;
AudioBoard board(AudioDriverSGTL5000, pins);
I2SStream i2s_stream;
//I2SCodecStream out(board);

bool beginAudio() {
    // We have to start I2S first to get MCLK going, before the SGTL5000
    // will respond to I2C.
    Serial.println("I2SConfig...");
    auto i2s_config = i2s_stream.defaultConfig(TX_MODE);
    i2s_config.copyFrom(info);
    i2s_config.pin_bck = PIN_I2S_BCLK;
    i2s_config.pin_data = PIN_I2S_DOUT;
    i2s_config.pin_mck = PIN_I2S_MCLK;
    i2s_config.pin_ws = PIN_I2S_LRCLK;
    if (!i2s_stream.begin(i2s_config)) {
        Serial.println("I2SStream.begin() FAILED");
        return false;
    }
    delay(400);

    // Now that MCLK is running, we can talk to the chip over I2C.
    Serial.printf("Pins... %04X\r\n", readReg(SGTL5000::Reg::ChipId));

    if (!pins.addI2C(PinFunction::CODEC, Wire)) {
        Serial.println("pins.addI2C() FAILED");
        return false;
    } 
    Serial.printf("Board... %04X\r\n", readReg(SGTL5000::Reg::ChipId));
    if (!board.begin()) {
        Serial.println("board.begin() FAILED");
        return false;
    }

    // Start the sine wave generator.
    Serial.println("Sine...");
    if (!usb_stream.begin(info)) {
        Serial.println("in.begin() FAILED");
        return false;
    }
    if (!sineWave.begin(info, N_B4)) {
        Serial.println("board.begin() FAILED");
        return false;
    }
    return true;
}

And here's the console output:

--- Terminal on /dev/ttyACM0 | 9600 8-N-1
--- Available filters and text transformations: debug, default, direct, hexlify, log2file, nocontrol, printable, send_on_enter, time
--- More details at https://bit.ly/pio-monitor-filters
--- Quit: Ctrl+C | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H
I2SConfig...
[I] AudioTypes.h : 122 - out: sample_rate: 44100 / channels: 2 / bits_per_sample: 16
[I] I2SDriverRP2040.h : 52 - virtual bool audio_tools::I2SDriverRP2040::begin(audio_tools::I2SConfigStd)
[I] AudioTypes.h : 122 -  sample_rate: 44100 / channels: 2 / bits_per_sample: 16
[I] I2SConfigSTD.h : 91 - rx/tx mode: TX_MODE
[I] I2SConfigSTD.h : 93 - is_master: Master
[I] I2SConfigSTD.h : 94 - sample rate: 44100
[I] I2SConfigSTD.h : 95 - bits per sample: 16
[I] I2SConfigSTD.h : 96 - number of channels: 2
[I] I2SConfigSTD.h : 97 - i2s_format: I2S_STD_FORMAT
[I] I2SConfigSTD.h : 98 - buffer_count:6
[I] I2SConfigSTD.h : 99 - buffer_size:512
[I] I2SConfigSTD.h : 103 - pin_mck: 21
[I] I2SConfigSTD.h : 105 - pin_bck: 19
[I] I2SConfigSTD.h : 107 - pin_ws: 20
[I] I2SConfigSTD.h : 109 - pin_data: 18
[I] I2SDriverRP2040.h : 222 - Using MCK pin: 21 with multiplier 64
write():  1  1
endTransmission: 0
requestFrom: 2
Pins... A011
write():  1  1
endTransmission: 0
requestFrom: 2
Board... A011
Info:    AudioDriver::begin
Info:    setupI2CAddress: 0xa
Info:    ==> Updating address: 0xa
Info:    sd_active: 0
Info:    sdmmc_active: 0
Info:    AudioDriver::setConfig
Error:   ->p_wire->endTransmission: 4
Error:   ->p_wire->endTransmission: 4
Error:   ->p_wire->endTransmission: 4
Error:   ->p_wire->endTransmission: 4
Error:   ->p_wire->endTransmission: 4
Error:   ->p_wire->endTransmission: 4
Error:   ->p_wire->endTransmission: 4
setVoiceMute.writeReg()
Error:   ->p_wire->endTransmission: 4
setVoiceMute.writeReg()
Error:   ->p_wire->endTransmission: 4
Error:   AudioDriver controlState failed
Error:   setConfig has failed
Error:   AudioBoard::driver::begin failed
board.begin() FAILED
write():  1  1
endTransmission: 4
requestFrom: 0
FFFF

Setting up I2SStream first, I2C is responding correctly. Look for A011 in the output, that's the output of getting register 0, Chip ID. It's just a simple "is it working and responding?" register.

Board... A011 shows that its still responding as its calling board.begin(). Inside there, it gets down to AudioDriver::setConfig() where endTransmission() starts responding with 4, meaning it's not being ACKd on I2C.

So, something in board.begin() is breaking either I2C, or MCLK on I2S. I'll keep digging into the Board code, see if I can figure out where it is.

[pschatzmann]

Cool, I changed the logic in I2SCodecStream to set up I2S before the codec: so your initial intended functionality should work as well

[pschatzmann]

Oh, i am confused: I have seen the message that it is working, but it seems that you have deleted it. If it is not working I suggest set the audio driver to debug mode and activate the ESP32 logging: I dont see anywhere how you define the i2c pins..

[SmittyHalibut]

Yeah, sorry. So, initializing I2S before I2C is correct. So I think the initial problem is this issue is resolved.

But it's still not working, and I think it's something else unrelated. Would you like me to open a separate issue for it?

Summary: The SGTL5000 stops responding after writing to the DigPower register.

Debug:   writeReg(Reg::AnaCtrl)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x2400 
Debug:   writeReg(Reg::AnaPower)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x3000 
Debug:   writeReg(Reg::DigPower)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x0200 
Debug:   writeReg(Reg::LineOutVol)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x2E00 
Error:   ->p_wire->endTransmission: 4
Debug:   writeReg(Reg::SssCtrl)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x0A00 
Error:   ->p_wire->endTransmission: 4
Debug:   writeReg(Reg::AdcDacCtrl)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x0E00 
Error:   ->p_wire->endTransmission: 4

[pschatzmann]

Please provide the full log: is any transactins successful ? So far I do not see that you use the right pins...

[SmittyHalibut]

Full log:

--- Terminal on /dev/ttyACM1 | 9600 8-N-1
--- Available filters and text transformations: debug, default, direct, hexlify, log2file, nocontrol, printable, send_on_enter, time
--- More details at https://bit.ly/pio-monitor-filters
--- Quit: Ctrl+C | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H
I2SConfig...
[D] I2SStream.h : 78 - bool audio_tools::I2SStream::begin(audio_tools::I2SConfig)
[D] BaseStream.h : 129 - virtual void audio_tools::AudioStream::setAudioInfo(audio_tools::AudioInfo)
[I] AudioTypes.h : 122 - out: sample_rate: 44100 / channels: 2 / bits_per_sample: 16
[I] I2SDriverRP2040.h : 52 - virtual bool audio_tools::I2SDriverRP2040::begin(audio_tools::I2SConfigStd)
[I] AudioTypes.h : 122 -  sample_rate: 44100 / channels: 2 / bits_per_sample: 16
[I] I2SConfigSTD.h : 91 - rx/tx mode: TX_MODE
[I] I2SConfigSTD.h : 93 - is_master: Master
[I] I2SConfigSTD.h : 94 - sample rate: 44100
[I] I2SConfigSTD.h : 95 - bits per sample: 16
[I] I2SConfigSTD.h : 96 - number of channels: 2
[I] I2SConfigSTD.h : 97 - i2s_format: I2S_STD_FORMAT
[I] I2SConfigSTD.h : 98 - buffer_count:6
[I] I2SConfigSTD.h : 99 - buffer_size:512
[I] I2SConfigSTD.h : 103 - pin_mck: 21
[I] I2SConfigSTD.h : 105 - pin_bck: 19
[I] I2SConfigSTD.h : 107 - pin_ws: 20
[I] I2SConfigSTD.h : 109 - pin_data: 18
[I] I2SDriverRP2040.h : 222 - Using MCK pin: 21 with multiplier 64
write():  1  1
endTransmission: 0
requestFrom: 2
Pins... A011
write():  1  1
endTransmission: 0
requestFrom: 2
Board... A011
Debug:   AudioBoard::begin
Info:    AudioDriver::begin
Info:    setupI2CAddress: 0xa
Info:    ==> Updating address: 0xa
Info:    sd_active: 0
Debug:   DriverDeviceInfo::setSPIActiveForSD: 0
Info:    sdmmc_active: 0
Debug:   DriverDeviceInfo::setSDMMCActive: 0
Debug:   DriverDeviceInfo::begin
Debug:   DriverDeviceInfo::setupPinMode
Info:    AudioDriver::setConfig
Debug:   writeReg(Reg::AnaPower)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x3000 
Debug:   writeReg(Reg::LinregCtrl)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x2600 
Debug:   writeReg(Reg::RefCtrl)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x2800 
Debug:   writeReg(Reg::LineOutCtrl)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x2C00 
Debug:   writeReg(Reg::ShortCtrl)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x3C00 
Debug:   writeReg(Reg::AnaCtrl)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x2400 
Debug:   writeReg(Reg::AnaPower)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x3000 
Debug:   writeReg(Reg::DigPower)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x0200 
Debug:   writeReg(Reg::LineOutVol)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x2E00 
Error:   ->p_wire->endTransmission: 4
Debug:   writeReg(Reg::SssCtrl)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x0A00 
Error:   ->p_wire->endTransmission: 4
Debug:   writeReg(Reg::AdcDacCtrl)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x0E00 
Error:   ->p_wire->endTransmission: 4
Debug:   writeReg(Reg::DacVol)
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x1000 
Error:   ->p_wire->endTransmission: 4
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x0600 
Error:   ->p_wire->endTransmission: 4
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x0400 
Error:   ->p_wire->endTransmission: 4
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x2200 
Error:   ->p_wire->endTransmission: 4
setVoiceMute.writeReg()
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x2400 
Error:   ->p_wire->endTransmission: 4
Debug:   mode->CODEC_MODE_BOTH
setVoiceMute.writeReg()
Debug:   i2c_bus_write_bytes: addr=0xA reglen=2 datalen=2 - reg=0x2400 
Error:   ->p_wire->endTransmission: 4
Error:   AudioDriver controlState failed
Error:   setConfig has failed
Error:   AudioBoard::driver::begin failed
board.begin() FAILED
write():  1  1
endTransmission: 4
requestFrom: 0
FFFF