Spresense and DFRobot HCHO sensor

[Kaduwela]

I am integrating the DFRobot HCHO (formaldehyde) sense with Spresense. I am running circuit-python on spresense. The HCHO sensor can do either UART or DAC. When I did UART using the code below, I got a stream of 'None..'

import time
import board
import busio

import digitalio

For most CircuitPython boards:

#uart = busio.UART(board.TX, D0, baudrate=9600)
uart = busio.UART(board.TX, board.RX)
#uart = board.UART(baudrate=9600)
time.sleep(2)

while True:

time.sleep(0.1)
data = uart.read()
time.sleep(0.1)

The HCHO sensor is a three wire thing. Two for power and one for RX.

I must be doing something wrong here. Do you see what it is?
Now I am trying to use DAC with A2 pin. My questions are

1. What is reference voltage for this pin? (I have JP1 jumper set to 3V3 for several other sensors I am incorporating)
2. Is the DAC truly 10-bit or is it acting as it is 16-bit?

[KamilTomaszewski]

Hi @kaduwela

Did you connect the signal to the main board or extension board?

Here is the link to the documentation: https://developer.sony.com/develop/spresense/docs/circuitpython_tutorials_en.html#_circuitpython_uart

Reference Voltage of A2 and A3 pins on Main board is 0.7V.
Reference Voltage of A0 ~ A5 pins on Extension board is 5.0V.

It is 10-bit but value is outputted as unsigned 16-bit data.

Best Regards,
Kamil Tomaszewski