Hi,

I'm new here, and after some help. I'm having an issue with my raspberry pi pico communicating with my DFRobot Gravity O2 sensor via UART. I can get the O2 values from the sensor in the default ‘initiative’ mode where it sends data every 1 sec and the values seem fine. However when I send FF 01 78 04 00 00 00 00 83 to sent to question/answer mode, I do not get the confirmation of mode being set (78 01 00 00 00 00 00 87) and the sensor continues to read every second giving a signal that start ‘ FF 88’ suggesting it is still in default mode (I should be getting a response starting FF 86 as per these instructions ).

Does anyone have any suggestions? Could it be a hardware issue or is it my code?

My micropython code is:

from machine import UART, Pin
from time import sleep

uart0 = UART(0, baudrate=9600, tx=Pin(0), rx=Pin(1), timeout=500)#the UART pins are actually backward on the sensor
uart0.init(9600, bits=8, stop=1)#maybe comment out
uart0.flush()
sleep(1)

while True:

sleep(1)
uart0.flush()
#request question/answer mode, expected response 'xff x78 x01 x00 x00 x00 x00 x00 x87
sequence_to_send =b'\xff\x01\x78\x04\x00\x00\x00\x00\83'
uart0.write(sequence_to_send)
if uart0.any():
O2uart = uart0.read()

print("{}".format(O2uart))
else:
print("O2 Sensor Error")
#actual response "b'\xff\x88\x00\xc9\x05\x01\x01\xe4\xa8\"
uart0.flush()
sleep(1)
#request read, expected response starts '\xff\x86'
sequence_to_send =b'\xff\x01\x86\x04\x00\x00\x00\x00\79'
uart0.write(sequence_to_send)
if uart0.any():
O2uart = uart0.read()

print("{}".format(O2uart))
else:
print("O2 Sensor Error")
#actual response starts 'xff\x88'

The working code for measureing O2 from the default initiative mode is:

from machine import UART, Pin
from time import sleep

uart0 = UART(0, baudrate=9600, tx=Pin(0), rx=Pin(1), timeout=500)#the UART pins are actually backward on the sensor
uart0.init(9600, bits=8, stop=1)#maybe comment out
uart0.flush()
sleep(1)

while True:
uart0.flush()

sleep(1)

if uart0.any():
O2uart = uart0.read()
O2high = O2uart[2]
O2low = O2uart[3]
O2 = (O2high * 256 + O2low)*0.1

print("{}%".format(O2))
else:
print("O2 Sensor Error")