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I may be asking about something that has already been done, so apologies if that is the case...

I have a USB GPS plugged into one of the USB ports on my RPi(2). It works now in that GPS data is passed and processed by RPi based applications.

What I want to do, is to take that same GPS data string moving to/from the GPS device via the RPi's USB port and move it to/from the GPIO as TTL level (not RS-232, but serial nonetheless) data that it may be used on other devices which do not have USB host capability and therefor cannot communicate to a USB GPS.

In the current setup, most application are looking at the USB GPS as being on a virtual com port (/dev/ttyUSBxx).

So I suppose what I am wanting to do is send/receive serial GPS data between a USB based virtual com port and a GPIO virtual com port.

A virtual 'router' or 'message switch' if you will.

What I am NOT looking to create is a USB port using the GPIO.

Physical: USB GPS <---> RPi USB port---RPi GPIO <---> GPS Data to/from other devices.

Logical: USB GPS Data <----- GPS Data Routed in RPi ----> GPIO GPS Data

R Marks
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1 Answers1

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You could do it with the pyserial package http://pyserial.readthedocs.io/en/latest/pyserial.html

Create two instances, one for the usb port, the second for the UART (GPIO14/GPIO15)

read from usb port, process the gps data, if it is necessary and finally write it to the uart. 

import serial

reading = True

serial_usb = serial.Serial('/dev/ttyUSB0', 9600)
serial_uart = serial.Serial('/dev/ttyAMA0', 9600)

while reading:
    gps_data = str(serial_usb.readline(), 'utf-8').split(',')
    # process the gps_data
    serial_uart.write(bytes(gps_data))
bierschi
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