Test script for the steppers of BTT SKR Pico. Derived from janelia-arduino/TMC2209's example of the same name.

StallGuard.ino

#include <TMC2209.h>

// This example will not work on Arduino boards without HardwareSerial ports,
// such as the Uno, Nano, and Mini.
//
// See this reference for more details:
// https://www.arduino.cc/reference/en/language/functions/communication/serial/

HardwareSerial & serial_stream = Serial2;

const long SERIAL_BAUD_RATE = 115200;
const int DELAY = 200;
// current values may need to be reduced to prevent overheating depending on
// specific motor and power supply voltage
const uint8_t RUN_CURRENT_PERCENT = 100;
const int32_t VELOCITY = 2000;
const uint8_t STALL_GUARD_THRESHOLD = 50;

// X Z Y E
const uint8_t STEPPER_ENA[4] = { 12,  2, 7, 15 };
const uint8_t STEPPER_STP[4] = { 11, 19, 6, 14 };
const uint8_t STEPPER_DIR[4] = { 10, 28, 5, 13 };
const uint8_t STEPPER_INT[4] = {  4, 25, 3, 16 };
const TMC2209::SerialAddress STEPPER_ADDR[4] = { TMC2209::SERIAL_ADDRESS_0, TMC2209::SERIAL_ADDRESS_1, TMC2209::SERIAL_ADDRESS_2, TMC2209::SERIAL_ADDRESS_3 };

// Instantiate TMC2209
TMC2209 stepper_driver;

void setup()
{
  uint8_t channel = 0;

  pinMode(STEPPER_ENA[channel], OUTPUT);

  Serial.begin(SERIAL_BAUD_RATE);

  stepper_driver.setup(serial_stream, SERIAL_BAUD_RATE, STEPPER_ADDR[channel]);
  stepper_driver.setRunCurrent(RUN_CURRENT_PERCENT);
  stepper_driver.setStallGuardThreshold(STALL_GUARD_THRESHOLD);
  stepper_driver.setMicrostepsPerStepPowerOfTwo(1);

  pinMode(STEPPER_STP[channel], OUTPUT);
  digitalWrite(STEPPER_ENA[channel], 0);
  analogWriteFreq(2000);
  analogWrite(STEPPER_STP[channel], 127);
}

void loop()
{
  if (not stepper_driver.isSetupAndCommunicating())
  {
    Serial.println("Stepper driver not setup and communicating!");
    return;
  }

  Serial.print("run_current_percent = ");
  Serial.println(RUN_CURRENT_PERCENT);

  Serial.print("stall_guard_threshold = ");
  Serial.println(STALL_GUARD_THRESHOLD);

  uint16_t stall_guard_result = stepper_driver.getStallGuardResult();
  Serial.print("half_stall_guard_result = ");
  Serial.println(stall_guard_result / 2);

  Serial.println();
  delay(DELAY);
}

The run current is all messed up... this is effectively useless.