Hello,
I know the question is not directly related to the library, but I still want to give it a shot, since I am a bit stuck there.

I have a MCP3561 with a MAX4208 amplifier to measure the voltage at the output of a strain gauge. The MCP3561 is drived by an ESP32 using this library. I would like the system to work in continuous mode in MUX mode (differential).
Everything is working well (config settings, continuous mode, irq pin) but I have very strange steps showing in the output signal. It seems to be related to some specific ADC count values, and I can't find anything similar on the web too. After some digging I found out that sometimes, somehow, a group of samples has missing ADCDATA bytes, always the less significant ones. So data like 0x3Cxxxx becomes 0x3C0000 and it stays like this until a high/low enough sample appears and change the current value.

Like you can see on this picture (values are calibrated values for my use), there are somes value-based steps appearing at 11.27-21.68-31.04, on the ascent and the descent of the curve.

There is a small antialiasing filter consisting of two RC (1k/100n) filters in between, like in the schematics of the weight scale example application provided by microchip

I have tried with a signal generator directly on the input of the antialiasing filter and it still the same.

If you have any clue or something I could check/test/do to know what's causing this issue...

Hi,

I noticed that you have two licenses: CC0 and MIT. However, they seem pretty identical to me. Is it legal to include just one of the licenses?

Also, this is my first time adding a license. I don't know what the typical approach is for doing this. Should I add the full text of MIT/CC0 in the specific library, or should I create another folder to hold all the licenses?

Keep receiving a value of zero from analogRead. Moving this into its own issue from: #5 (comment)

How is the “_status.dr” logic changed?
(In the IRQ_handler() does not change the “_status.dr”)
Thanks

Recently I run in to some issue that got me good : that is the timming of CS pin pulldown

Another question: does the noInterrupts(); effect on the Interrupts that was pinned to another esp32 core?

Hi,
first of all thank you very much for the code. I was very happy to find something for this ADC family.
Unfortunately the code does not run on my MCP3464 yet. The signals from the CLK, CS and SDI look good but unfortunately the ADC at the SDO gives nothing out. Only a small ripple from the CLK is visible on the Scope. Do you have an idea where the problem could be?

I would be very grateful for any information.
Thanks a lot

Hi!
I'm having some trouble compiling my code after adding this library.
Most likely I'm doing something dumb, but would appreciate any input.

I include and initialise it like this:

#include "lib/MCP3x6x/MCP3x6x.h"
MCP3464 ext_mcp_adc(ADC_CS_PIN, &SPI, ADC_MOSI_PIN, ADC_MISO_PIN, ADC_SCK_PIN);

Then I get the following errors:

Linking .pio/build/PicoADK/firmware.elf
/Users/hallwrk/.platformio/packages/toolchain-rp2040-earlephilhower/bin/../lib/gcc/arm-none-eabi/10.3.0/../../../../arm-none-eabi/bin/ld: .pio/build/PicoADK/src/main.cpp.o: in function `_GLOBAL__sub_I_tft':
main.cpp:(.text.startup._GLOBAL__sub_I_tft+0x42): undefined reference to `_ZN7MCP3x6xC2EhhthPN7arduino11HardwareSPIEhhh'
/Users/hallwrk/.platformio/packages/toolchain-rp2040-earlephilhower/bin/../lib/gcc/arm-none-eabi/10.3.0/../../../../arm-none-eabi/bin/ld: .pio/build/PicoADK/src/main.cpp.o: in function `loop':
main.cpp:(.text.loop+0x98): undefined reference to `_ZN7MCP3x6x20analogReadContinuousENS_3MuxE'

(and so on)

I have some other peripherals on the two SPI channels which are working fine, an OLED and a DAC.

Last year you discovered my repo for this chip and even helped out.
https://github.com/fhnw-ise-qcrypt/mcp3564

I just wanted to let you know that my library is now at a point where it is working in a product that I am still developing.
https://github.com/fhnw-ise-qcrypt/stm32-wiggly-pointy

And I came up with a conf.h file to have various configuration examples because this chip is just so damn adaptable.
So feel free to cheat by looking through my code. This is how I handle the "streaming" mode via GPIO interrupts. It actually works according to the timing from the Excel sheet:
https://github.com/fhnw-ise-qcrypt/stm32-wiggly-pointy/blob/main/Core/Src/stm32f3xx_it.c#L225

I am really curious how you implement the Stream class as I have seen in the example that you want to achieve.

Not really an issue, more of a question so apologies...

I'm attempting to read from channel 0 in mux mode but having issues even entering the setup and loop sections. I'm assuming it's something to do with my mcp definition since I've tested the println function and it seems to work. I'm using an Arduino Zero which is SAMD21. I added a lot of print statements to try and figure out where the program is/isn't making it to. If I go by these statements, the setup and loop aren't being read. Assuming that I've done something really dumb since I'm quite new to this.

MCP3462 mcp(10); //the problem?

void setup() {
Serial.begin(115200);
while (!Serial)
;
Serial.println(FILE);
if (!mcp.begin()) {
Serial.println("failed to initialize MCP");
while (1)
;
}
}

// the loop routine runs over and over again forever:
void loop() {
// read the input on default analog channel:
int32_t adcdata = mcp.analogRead(MCP_CH0);

// Convert the analog reading
double voltage = adcdata * mcp.getReference() / mcp.getMaxValue();
Serial.println("converted voltage");

// print out the value you read:
Serial.println("voltage: ");
Serial.print(voltage, 10);
Serial.println("printed voltage");

// pause program for one second
delay(1000);
}

Hi, it's me again

I found out while the value should be negative number returns a very large positive number when I'm in data_format::SGN_DATA (int24)mode. For example, when the ADCDATA REGISTER have value FFFE2F, _getValue(raw) will return 16776751 while it should return -465;

The problem happend here:

I can't figure out what when wrong so I modified it like this:

case (data_format::SGN_DATA):  
  if(bitRead(raw, 23)){
    return (((~raw+1) & 0x7FFFFF)*-1);  // OR return((0x1000000 - raw & 0x7FFFFF)*-1);
  }else{
    return raw & 0x7FFFFF;
  }

if MSB==1(Negative Number), turn it to nergative number by two's complement, but we don't need to consider bytes greater then 22(0~22). So we & 0x007FFFFFF, but we still needs the negative sign so *-1.

I think there is some way to simplify this but this will work for me.

void MCP3x6x::setConfig0(){
  settings.config0.vref_sel=1;
  settings.config0.cfg0=1;
  settings.config0.clk=clk_sel::INTERN;
  settings.config0.bias=cs_sel::BIAS_0UA;
  settings.config0.adc=adc_mode::STANDBY;
  _status = write(settings.config0);
}
void MCP3x6x::setConfig1(){
  settings.config1.pre=pre::MCLK_0;
  settings.config1.osr=osr::OSR_256;
  _status = write(settings.config1);
}
void MCP3x6x::setConfig2(){
  settings.config2.boost=boost::BOOST_1;
  settings.config2.gain=gain::GAIN_32;
  settings.config2.az_mu=0;
  settings.config2.az_ref=1;
  settings.config2.reserved=1;
  _status = write(settings.config2);
}
void MCP3x6x::setConfig3(){
  settings.config3.conv_mode=conv_mode::CONTINUOUS;
  settings.config3.data_format=data_format::SGN_DATA;
  settings.config3.crc_format=0;
  settings.config3.en_crccom=0;
  settings.config3.en_offcal=1;
  settings.config3.en_gaincal=1;
  _status = write(settings.config3);
}
bool MCP3x6x::begin(uint16_t channelmask, float vref) {
  pinMode(_pinCS, OUTPUT);
  digitalWrite(_pinCS, HIGH);
  
  _spi->begin(_pinCLK,_pinMISO,_pinMOSI,_pinCS);
  _status = reset();

  setConfig0();
  setConfig1();
  setConfig2();
  setConfig3();
  return true;
}

to check if the counfigurations actually apply to MCP3X6X

void MCP3x6x:: readBuffer(){  
  uint8_t buffer[1];
  _transfer(buffer, MCP3x6x_CMD_IREAD | MCP3x6x_ADR_CONFIG0);
  Serial.printf("CONFIG0: %02X\n",buffer[0]);

  _transfer(buffer, MCP3x6x_CMD_IREAD | MCP3x6x_ADR_CONFIG1);
  Serial.printf("CONFIG1: %02X\n",buffer[0]);

  _transfer(buffer, MCP3x6x_CMD_IREAD | MCP3x6x_ADR_CONFIG2);
  Serial.printf("CONFIG2: %02X\n",buffer[0]);
  
  _transfer(buffer, MCP3x6x_CMD_IREAD | MCP3x6x_ADR_CONFIG3);
  Serial.printf("CONFIG3: %02X\n",buffer[0]);
}

Best,

Hi,
Thank you for making this ADC library. It's one of the few library that support MCP3562.

But when I'm implement this code to my ESP32 S3 it seems to stuck in analogread infinite loop.
The differences are I make the MCP3562 instance aka mcp a global instance by adding extern MCP3562 mcp; in MCP3x6x.h and MCP3562 mcp=MCP3562(); in MCP3x6x.cpp .
Also dude to the layout error I swap the pin definition of MISO & MOSI in the class Constructor .

MCP3x6x::MCP3x6x(const uint16_t MCP3x6x_DEVICE_TYPE, const uint8_t pinCS, SPIClass *theSPI,
                 const uint8_t pinMOSI, const uint8_t pinMISO, const uint8_t pinCLK) {
  switch (MCP3x6x_DEVICE_TYPE) {
    case MCP3461_DEVICE_TYPE:
      _resolution_max = 16;
      _channels_max   = 2;
      break;
    case MCP3462_DEVICE_TYPE:
      _resolution_max = 16;
      _channels_max   = 4;
      break;
    case MCP3464_DEVICE_TYPE:
      _resolution_max = 16;
      _channels_max   = 8;
      break;
    case MCP3561_DEVICE_TYPE:
      _resolution_max = 24;
      _channels_max   = 2;
      break;
    case MCP3562_DEVICE_TYPE:
      _resolution_max = 24;
      _channels_max   = 4;
      break;
    case MCP3564_DEVICE_TYPE:
      _resolution_max = 24;
      _channels_max   = 8;
      break;
    default:
#warning "undefined MCP3x6x_DEVICE_TYPE"
      break;
  }

  //  settings.id = MCP3x6x_DEVICE_TYPE;
/* ========================================= */

  _spi        = theSPI;
  _pinMISO    = pinMOSI;//SWAP DUE TO LAYOUT ERROR
  _pinMOSI    = pinMISO;//SWAP DUE TO LAYOUT ERROR
  _pinCLK     = pinCLK;
  _pinCS      = pinCS;

  Serial.print("_pinMISO: ");
  Serial.println(_pinMISO);
  Serial.print("_pinMOSI: ");
  Serial.println(_pinMOSI);
  Serial.print("_pinCLK: ");
  Serial.println(_pinCLK);
  Serial.print("_pinCS: ");
  Serial.println(_pinCS);

/* ========================================= */

  _resolution = _resolution_max;
  _channel_mask |= 0xff << _channels_max;  // todo use this one
};

And this is my main task

#include <SPI.h>
#include "MCP3x6x.h"

void setup()
{  
  Serial.begin(115200);  
  while (!mcp.begin()) {
    Serial.println("failed to initialize MCP");
    delay(200);
  }
}
void loop()
{
  Serial.println("1");//stuck detect
  int32_t adcdata = mcp.analogRead(MCP_CH0);
  Serial.println("2");//stuck detect
  double voltage = adcdata * mcp.getReference() / mcp.getMaxValue();  
  Serial.print("voltage: ");
  Serial.println(voltage, 10);
  delay(1000);
}

And the Serial out put:
_pinMISO: 11
_pinMOSI: 13
_pinCLK: 12
_pinCS: 10
1
mux

Any advice is greatly appreciated.