CODEWITHSUNDEEP
i2cmicropythonraspberry-pi-picoadafruit-circuitpython
neil.morrison
neil.morrison

Reputation: 123

Trouble using I2C in CircuitPython (working MicroPython example)

I'm trying to write some code to run on a Pi Pico to interface with a SNES Mini controller & provide a normal gamepad output (HID device style).

So I finished the following MicroPython code before realising MicroPython (on the Pico) can't do any sort of HID device stuff:

import machine
import time

GAMEPAD_ADDR = 0x52
FREQ_MOD = 3

i2c = machine.I2C(0, scl=machine.Pin(
    17), sda=machine.Pin(16), freq=int(100000 * FREQ_MOD))

i2c.writeto_mem(GAMEPAD_ADDR, 0x40, b'\x00')
time.sleep(0.05)


def reconnect():
    i2c.writeto_mem(GAMEPAD_ADDR, 0x40, b'\x00')
    time.sleep(0.05 / FREQ_MOD)


while True:
    i2c.writeto(GAMEPAD_ADDR, b'\x00')
    time.sleep(0.05 / FREQ_MOD)
    data = i2c.readfrom(GAMEPAD_ADDR, 6)

    if (data[1] == 255):
        reconnect()
    else:
        dataA = 0x17 + (0x17 ^ data[4])
        dataB = 0x17 + (0x17 ^ data[5])

        if not (dataB & ~0b11111110):
            print("UP")
        if not (dataB & ~0b11111101):
            print("LEFT")
        if not (dataA & ~0b10111111):
            print("DOWN")
        if not (dataA & ~0b01111111):
            print("RIGHT")
        if not (dataA & ~0b11011111):
            print("L")
        if not (dataA & ~0b11111101):
            print("R")
        if not (dataB & ~0b11101111):
            print("A")
        if not (dataB & ~0b10111111):
            print("B")
        if not (dataB & ~0b11011111):
            print("Y")
        if not (dataB & ~0b11110111):
            print("X")
        if not (dataA & ~0b11101111):
            print("SELECT")
        if not (dataA & ~0b11111011):
            print("START")

Which isn't neat but it works, (the reconnect bit is a little weird not sure why it disconnects & needs the set up byte again), it'll print out whichever key is being pressed.

So far I've got the following CircuitPython code:

import time
import board
import busio
from adafruit_bus_device.i2c_device import I2CDevice

FREQ_MOD = 3

i2c = busio.I2C(board.GP17, board.GP16, frequency=30000)

while not i2c.try_lock():
    pass

time.sleep(0.01)

print([hex(x) for x in i2c.scan()])

time.sleep(0.01)
data = bytearray(6)

i2c.writeto(0x52, bytes([0x40, 0x00]))
time.sleep(0.01)

while True:
    i2c.writeto_then_readfrom(0x52, bytes([0x00]), data, out_start=0)
    print(data)
    time.sleep(1)

i2c.deinit()

But I'm not able to do the setup bit correctly so it just keeps reading bytearray(b'\xff\xff\xff\xff\xff\xff').

I think I just need the CircuitPython equivalent to MicroPython's i2c.writeto_mem(0x52, 0x40, b'\x00') then I should be fine from there.

It could also be that the writeto_then_readfrom isn't equivalent to what's done in the MicroPython.

Thanks

Upvotes: 0

Views: 2321

Answers (1)

neil.morrison
neil.morrison

Reputation: 123

Just worked it out immediately after posting - the writeto_then_readfrom isn't what I wanted to use.

while True:
    i2c.writeto(0x52, bytes([0x00]))
    time.sleep(0.01)
    i2c.readfrom_into(0x52, data)
    print(data)
    time.sleep(1)

This gets CircuitPython behaving in the way MicroPython was (but seemingly without the random disconnect, which is nice).

Upvotes: 1

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