Working with sps30 and esp32 on micropython

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Hello!

I am trying to make the sps30 work with the esp32 but with micropython. I found a library online but it tested using raspberri pi: sps30/sps30.py at master · feyzikesim/sps30 · GitHub so I tried converting it to a usable code for esp32.

I am having problems writing on the i2c bus For example, on the original code:


SPS_ADDR = 0x69
…
R_ARTICLE_CD = [0xD0, 0x25]
…

def read_article_code(self):
result =[]
article_code =[]

    write = i2c_msg.write(self.SPS_ADDR, self.R_ARTICLE_CD)
    self.bus.i2c_rdwr(write)

    read = i2c_msg.read(self.SPS_ADDR, 48)
    self.bus.i2c_rdwr(read)

    for i in range(read.len):
        result.append(bytes_to_int(read.buf[i]))

    if checkCRC(result):
        for i in range (2, len(result), 3):
            article_code.append(chr(result[i-2]))
            article_code.append(chr(result[i-1]))
        return str("".join(article_code))
    else:
        return self.ARTICLE_CODE_ERROR

The code I was able to do was:

SPS_ADDR = b’\x69’
…
R_ARTICLE_CD = bytearray([0xD0, 0x25])
…

def read_article_code(self):
    result = []
    article_code = []

    write = bytearray(self.R_ARTICLE_CD)
    self.i2c.writeto(self.SPS_ADDR, write)

    time.sleep(0.1)

    read = bytearray(48)
    self.i2c.readfrom_into(self.SPS_ADDR, read)
    
    for i in range(read.len):
        result.append(bytes_to_int(read.buf[i]))

    if checkCRC(result):
        for i in range (2, len(result), 3):
            article_code.append(chr(result[i-2]))
            article_code.append(chr(result[i-1]))
        return str("".join(article_code))
    else:
        return self.ARTICLE_CODE_ERROR

The terminal outputs TypeError: can’t convert bytes to int on the self.i2c.writeto(self.SPS_ADDR, write) line. I’m guessing this would happen on the read part also.

I am hoping that maybe someone here could help me? Thanks!

2

I’ve never used microPython, only regular Python, but to me it looks like it’s complaining because you changed what’s passed from an integer (SPS_ADDR = 0x69) to bytes (SPS_ADDR = b’\x69)

3

when I do that, it outputs: OSError: [Errno 116] ETIMEDOUT on the same line. I checked my wirings and i think they are still good. Any other ideas?

4

It appears MicroPython does not support the standard Python smbus2 library. Which means MicroPython also does not support this sps30 library.

I think you are supposed to use the MicroPython Machine library for your processor when using I2C.
https://docs.micropython.org/en/latest/library/machine.I2C.html

I searched around and it appears nobody has written a device driver library for the SPS30 sensor that is compatible with MicroPython.

I did find a driver written for CircuitPython.

So if you don’t mind switching the project from MicroPython to CircuitPython, I suspect you’ll have a much easier time getting it to wok.

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