UART on Lopy not recognizing non-default pins

Reply to UART on Lopy not recognizing non-default pins on Fri, 21 Sep 2018 21:11:20 GMT

Paloma — Fri, 21 Sep 2018 21:11:20 GMT

I'm trying to setup a LoPy 1.0 with expansion board 2.0 to read GPS data and write that data to an SD card. In the process of debugging the system I noticed that the SD and Uart1 share the use of pin G11/P4. I figured the best option would be to redefine the UART pins in order to be able to use both the UART and SD card at the same time.

My problem is that when I change the pins to something like P20 and P21 (like in the example) the board will not recognize input and instead continues to only accept data on the G11/P4 pin. Below is some test code that I wrote to try to figure this out. Any help would be greatly appreciated.

from machine import UART, Pin
from micropyGPS import MicropyGPS
import time

uart = UART(1,9600, pins = ('P21','P22'))
uart.init(9600,bits = 8, parity = None, stop = 1)

while(True):
    if(uart.any()):
        a = uart.read(100)
        print(a)
    else:
        print("No data")

Reply to UART on Lopy not recognizing non-default pins on Sat, 22 Sep 2018 10:39:00 GMT

Eric73 — Sat, 22 Sep 2018 10:39:00 GMT

@paloma
Hello i have fall in same trap than you (but with i2c pin)

uart = UART(1,9600, pins = ('P21','P22'))

You set P21 and P22 as TX/RX, but please notice that when you call

uart.init(9600,bits = 8, parity = None, stop = 1)

This function have again internaly default value for RX/TX pin according to pycom documentation -> uart.init(baudrate=9600, bits=8, parity=None, stop=1, * , timeout_chars=2, pins=(TXD, RXD, RTS, CTS))

So i strongly think that if you change your function call by

uart.init(baudrate=9600, bits=8, parity=None, stop=1, pins=('P21', 'P22'))

it will work as you want

Reply to UART on Lopy not recognizing non-default pins on Mon, 24 Sep 2018 16:25:27 GMT

Paloma — Mon, 24 Sep 2018 16:25:27 GMT

@eric73 This seems to have solved my problem! Thanks!