Pytrack and GPS Balloon mode

  • Hello,

    For a stratospheric balloon project, I'm going to ship a Pytrack card.
    But for the I76 GPS to operate at high altitude, it is necessary to activate the "balloon mode" :


    Therefore, send a frame $PMTK886,32B <CR> <LF> and wait for the answer $PMTK001,886,336.

    Has any of you tested and managed to send a frame to the Pytrack GPS module so that I do not start from scratch?

    Thanks for your help

  • @brunos: I think the application note of the gps ( there is one regarding i2c) mentioned to perform a dummy write like this. But I dont have that at hand right now...

  • @this-wiederkehr

    Thank you for the quick reply !
    I tested and I saw well the answer in the flow of the frames.
    What is the purpose of the line :

    self.i2c.writeto(GPS_I2CADDR, bytes([0])) 

  • @brunoS

    class L76GNSS:
        def __init__(self, py=None, sda='P22', scl='P21', writer=None):
            if py is not None:
                self.i2c = py.i2c
                from machine import I2C
                self.i2c = I2C(0, mode=I2C.MASTER, pins=(sda, scl))
            GPS_CONFIG = b'$PMTK314,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*28\r\n'
            self.i2c.writeto(GPS_I2CADDR, GPS_CONFIG)
            self.i2c.writeto(GPS_I2CADDR, bytes([0]))

    That is what I added in the init method to restrict sentence output. Be sure to have the correct checksum.

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