GPS on USB

Projects LimeNET
2

Hi @mpb,

It looks like you are looking to 2v0 version schematic, while all the backers got 2v1. Will assume 2v1 version.

There are two possibilities to get data from GNSS module to Raspberry Pi:

  1. Serial interface. GNSS_UART_TX is connected to FPGA via 0R resistor (fit by default) to RAPI_UART1_RX. GNSS_UART_RX is connected to FPGA via R56 resistor 0R (not fit by default) to RAPI_UART1_TX. This configuration enables FPGA and Raspberry receiving data from GNSS module TX line simultaneously. At the same time FPGA can send commands to GNSS module. If some application running on RPi module requires to control GNSS module, R57 must be soldered and must be ensured that FPGA pin is not configured as output. Baudrate is 9600. Hence you can get NMEA messages from /dev/serial1 already.
  2. USB interface. GNSS USB interface is connected to internal USB hub port 4 via 0R resistors R96 and R97. These resistors are not mounted by default - you have to solder them if you want to access GNSS module via USB. Baudrate is 9600.

Both GNSS module interfaces can work simultaneously and functionality is the same.