Communication between ESP32 and MCP3551

Projects Networking, Protocols, and Devices
1

I am trying to read RTD with MCP3551 over SPI...
Can anyone please guide me regarding any available resource for communication between ESP32 and MCP3551...
I have seen mcp3551.h file in man examples but now can't locate this file on entire google i have searched...
Will be obliged if someone can share this file to me, since there are demo examples available with this library which i can try....

Also if someone can give reference code for other 22/24 bit ADC over SPI with ESP32 then will be great guide....

2

Did you know that built into the ESP32 is a Sigma-delta Modulation module?

https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/sigmadelta.html

3

rohimo:
I am trying to read RTD with MCP3551 over SPI...
Can anyone please guide me regarding any available resource for communication between ESP32 and MCP3551...
I have seen mcp3551.h file in man examples but now can't locate this file on entire google i have searched...
Will be obliged if someone can share this file to me, since there are demo examples available with this library which i can try....

Also if someone can give reference code for other 22/24 bit ADC over SPI with ESP32 then will be great guide....

You don't really need a library for this.

Looking at the datasheet probably something like this could work:

(compiles but not tested!!!)

#include "SPI.h"

union {
  int32_t val;
  uint8_t bytes[4];
} conv;

void setup() {
  Serial.begin(115200);

  //Initialise SPI interface
  //SPI clock speed:5MHz, Data Shift:MSB First, Data Clock Idle: SPI_MODE3 (Mode 1,1)
  SPI.beginTransaction(SPISettings(5000000, MSBFIRST, SPI_MODE3));

  digitalWrite(SS, HIGH); //set CS pin HIGH (using board's default SPI SS pin)

  Serial.println("MCP3551 Single Conversion Example...");
}

void loop() {
  //Start conversion
  digitalWrite(SS, LOW); //set CS pin LOW
  delayMicroseconds(1);
  digitalWrite(SS, HIGH); //set CS pin HIGH

  //wait for conversion to complete
  delayMicroseconds(1);
  digitalWrite(SS, LOW); //set CS pin LOW
  while (digitalRead(MISO)); //wait for SDO/RDY to go low

  //read data
  conv.bytes[2] = SPI.transfer(0x00);
  conv.bytes[1] = SPI.transfer(0x00);
  conv.bytes[0] = SPI.transfer(0x00);

  digitalWrite(SS, HIGH); //set CS pin HIGH

  //check if conversion value is negative. adjust bytes[2] and bytes[3] accordingly
  if ( (conv.bytes[2] & 0x08 == 0x08) || ((conv.bytes[2] & 0x02 == 0x02) && (conv.bytes[2] & 0x04 == 0)) ) {
    conv.bytes[2] |= 0xC0; //bits 23-22 masked
    conv.bytes[3] = 0xFF;
  }
  else {
    conv.bytes[2] &= 0x3F; //bits 23-22 masked
    conv.bytes[3] = 0;
  }

  //print out data
  Serial.print("Overflow HIGH (OVH): ");
  if (conv.bytes[2] & 0x04 == 0x04) Serial.println("1");
  else Serial.println("0");

  Serial.print("Overflow LOW (OVL): ");
  if (conv.bytes[2] & 0x08 == 0x08) Serial.println("1");
  else Serial.println("0");

  Serial.print("Conversion value: ");
  Serial.println(conv.val, DEC);

  delay(1000); // Abitrary delay value for loop
}

hope that helps