Arduino library for reading from the LTC2440 ADC

Weird caveats

Haven't figured how to handle the data ready flag on the LTC2440 yet so don't sample more than the programmed sampling rate. Additionally, I haven't implemented programmable sampling rates so you're limited to 880Hz by setting SDI to GND or 7Hz by setting SDI to VCC.

The same sampling rate restriction applies to the .Tare(..) function, ie, pass >=2 into the millis_delay parameter.

Wiring

I'm using the DC570A evaluation board.

DC 570A	Teensy
SDO	MISO
SDI	GND (sets the sampling rate to 880Hz)
CS	pin 10
VCC	3v3
GND	GND

Example

Written for Platformio.

#include <Arduino.h>
#include "ltc2440.h"

#define kLTC2440CSPin 10

int32_t last_reading = 0;
float dt = 0.002; // [s]
float cutoff_dt = 0.005; // [s]
int32_t reading = 0;
int32_t last_print = 0;
float print_dt = 0.01; //[s]


LTC2440 torque_sensor(kLTC2440CSPin);

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

  delay(1000);
  torque_sensor.Tare(1000, 2);
}

void loop() {
  reading = torque_sensor.Read();
  float alpha = dt / (cutoff_dt + dt);
  last_reading = reading * alpha + last_reading * (1-alpha);
  delayMicroseconds(1000000 * dt);

  if (millis() - last_print > 1000 * print_dt) {
    last_print = millis();
    Serial.println(last_reading);
  }
}