QUESTION

Question

I have a M20071 Eval board that I would like to send $PAIR commands as listed in the M20071 NMEA Packet Manual.  I have had success sending commands like $PAIR002,*38 and $PAIR003*39 via the GNSSdemo GUI tool, but I would like to be able to send commands from outside this tool.  When I send commands like those I just mentioned from a serial monitor like TerraTerm, the Tx LED lights up on the eval kit momentarily as a confirmation that the board is receiving the message, but nothing else happens.  Is there some sort of procedure to send these commands that I'm missing?

Data sheet: Datasheet

M20071 NMEA Packet Manual: packet manual

Answer 1

Hi,
The GNSSdemo tool does not do anything extra, I think there might be a problem with the \r\n terminator.  I'll send you an email.

Michael

Answer 2

Also having this same issue. any resolution here?

Comments

Hi, this issue was resolved, it was related to the terminator characters. I'll send you an email, and see how we can help you.  Michael

Answer 3

Use the following python code to send a command.  I haven't worked out the best procedure to communicate with the device, but this should get you started.

Source: https://stackoverflow.com/questions/19143360/python-writing-to-and-reading-from-serial-port

import serial, time

ser = serial.Serial('/dev/ttyUSB1', 115200, timeout=0.5)

ser.write(b'$PAIR003*39\r\n')

time.sleep(0.1)

ser.close()

Comments

I slightly changed the reply above, I think it is worth trying some experiements with this line: GNSS_DATA_EINT.  Michael

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Initializing to HIGH and then setting to LOW, issuing command, then setting back to HIGH does not work.

Are there other commands that are being sent automatically by the gnss_demo application that maybe aren't described in the documentation?

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I've learnt that the timing on the GNSS_DATA_IN_EINT pin is important.  The PAIR command must be sent no later than 100ms after GNSS_DATA_IN_EINT goes low.  Also it best to wait 20ms after the pin goes low, therefore there's an 80ms window.  I hope that helps. Michael

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Still no luck on this. Can you send me whatever documentation you are working off of? Also, can you send me the firmware that the dev kits are flashed with? I have a python script where I'm successfully issuing PAIR commands. I'm assuming my GPIO assignments are messed up somewhere

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I'm sending you an email.  We want to understand why this isn't working, and will send an Eval board to you, to help fix this.
Michael