TMC2209 UART ESP32

[michaelboatboy]

I designed a PCB using an esp32-pico-d4 that also has a TMC2209 stepper driver. I would like to use the sensor-less homing feature that is only accessible through the UART protocol. I have succsefully established communication using this library: https://github.com/kjk25/TMC2209_ESP32 , but the code is huge and I would like to program the movement myself through the STEP/DIR protocal. I found a simple program that someone made here: https://forum.micropython.org/viewtopic.php?t=10697 ,but I could never get it working. I could not find a way to continue that discussion. Here is my code in that attempt:

import machine
from machine import Pin
from machine import UART
from time import sleep

# DIAG_PIN = Pin(13,Pin.IN) #, Pin.PULL_UP)input STALL motor
EN_PIN = Pin(12, Pin.OUT)  # output Enable
DIR_PIN = Pin(25, Pin.OUT)  # output Direction
STEP_PIN = Pin(27, Pin.OUT)  # output Step
DRIVER_ADDRESS = b'1'  # TMC2209 Driver address according to MS1 and MS2
STALL_VALUE = 2  # [0..255]
uart2 = UART(1, baudrate=115200, tx=5, rx=18)

###############################
# TMC2209 registermap
GCONF = 0x00
GSTAT = 0x01
IFCNT = 0x02
SLAVECONF = 0x03
OTP_PROG = 0x04
OTP_READ = 0x05
IOIN = 0x06
FACTORY_CONF = 0x07
IHOLD_IRUN = 0x10
TPOWER_DOWN = 0x11
TSTEP = 0x12
TPWMTHRS = 0x13
TCOOLTHRS = 0x14
VACTUAL = 0x22
SGTHRS = 0x40
SG_RESULT = 0x41
COOLCONF = 0x42
MSCNT = 0x6A
MSCURACT = 0x6B
CHOPCONF = 0x6C
DRV_STATUS = 0x6F
PWMCONF = 0x70
PWM_SCALE = 0x71
PWM_AUTO = 0x72

###############################


def compute_crc8_atm(datagram, initial_value=0):
    crc = initial_value
    # Iterate bytes in data
    for byte in datagram:
        # Iterate bits in byte
        for _ in range(0, 8):
            if (crc >> 7) ^ (byte & 0x01):
                crc = ((crc << 1) ^ 0x07) & 0xFF
            else:
                crc = (crc << 1) & 0xFF
            # Shift to next bit
            byte = byte >> 1
    return crc


def read_reg(mtr_id, reg):
    global uart2
    x = [0x55, 0, 0, 0]
    x[1] = mtr_id
    x[2] = reg
    x[3] = compute_crc8_atm(x[:-1])
    y = uart2.write(bytes(x))
    if y != len(x):
        print("Err in read")
        return False
    sleep(.01)
    if uart2.any():
        y = uart2.read(4)  # read what it self send and trash it (RX and TX one line)
        y = uart2.read()
    else:
        y = 0
    sleep(.000005)
    return y


def write_reg(mtr_id, reg, val):
    global uart2
    x = [0x55, 0, 0, 0, 0, 0, 0, 0]
    x[1] = mtr_id
    x[2] = reg | 0x80
    x[3] = 0xFF & (val >> 24)
    x[4] = 0xFF & (val >> 16)
    x[5] = 0xFF & (val >> 8)
    x[6] = 0xFF & val
    x[7] = compute_crc8_atm(x[:-1])
    y = uart2.write(bytes(x))
    if y != len(x):
        print("Err in write")
        return False
    sleep(.01)
    if uart2.any():
        y = uart2.read()  # read what it self send and trash it (RX and TX one line)
    sleep(.000002)


def init():
    print("init")
    global uart2
    uart2.init(115200, bits=8, parity=None, stop=1)

EN_PIN.value(0)
DIR_PIN.value(0)

z = 0
while True:
    z = z + 1
    a = read_reg(0, IOIN)
    print(a[3], a[4], a[5], a[6])
    print("##############################")
    a = read_reg(0, IFCNT)
    write_reg(0, GCONF, 0x000000020)
    b = read_reg(0, IFCNT)
    print("reading reg attempt", z)
    for i in bytearray(a):
        print("REG: ", hex(i))
        print("-")
    for i in bytearray(b):
        print("REG: ", hex(i))
    print("##############################")
    USRInput = input("read again?")
    init()```



The error: 


Traceback (most recent call last):
  File "<stdin>", line 111, in <module>
TypeError: 'NoneType' object isn't subscriptable

The error is caused because the esp32 does not receive anything.

Is this the best approach? Has someone else done something like this elsewhere  ?
Thanks in advance!
 

[robert-hh]

Since you already had a successful communication with the device, I assume that you have the 1k resistor between TX and RX, and the TMC2209 connected to the RX pin.
Do you have a separate means to see the signals on the wire, like a logic analyzer or at least a second MCU board, which just logs the data?
Comparing the code that worked and the one above and the data sheet, I do not see an obvious reason why it fails.

[michaelboatboy]

I did use a 1k resistor like I was supposed to. I do have a separate MCU although I should be able to see everything through the print statement. Do you think that is a necessary step? I have successfully communicated to the TMC2209 with Arduino code and that massive micro-python library I listed so I think the circuit and the UART settings should be fine. I could dissect the working bits of the library that worked and make my own library or try modifying it. Thanks!

[michaelboatboy]

I found the error! In the function read_reg, I had to set the mtr_id which was 1, not 0. Thanks for going through the trouble to try and help a random person like myself, I really appreciate it! Sorry that the error was just a stupid mistake.