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README.md

PmodGPS Hierarchical Block

Using the Hierarchical Block in Vivado

A tutorial for using Pmod Hierarchical Blocks in Vivado is available here. This Pmod Hierarchical Block does not require interrupts for normal operation, but the demo supplied with the drivers requires interrupts, be sure to connect them to an interrupt controller. Follow the section for connecting interrupts in the tutorial above if you will be using the demo. More details on interrupts and polling are available in the following section.

Demo Program in Xilinx SDK

The demo program continuously prints location data provided by the PmodGPS. That data is formatted as follows:

  • Latitude:
  • Longitude:
  • Altitude:
  • Number of Satellites:

If the PmodGPS fails to connect to the GPS satellites, the demo will only print out the line for number of satellites.

The demo program uses interrupts, but the Hierarchical Block can also be polled for data. To use the PmodGPS in polling mode, call the function GPS_getData(), then call the functions that return the information you want (getLatitude(), getLongitude(), etc.).

The PmodGPS generally has trouble connecting to the satellites while indoors. If you have connectivity issues, try taking the Pmod outdoors or next to a window. A way to see if the Pmod has been able to determine its location is to check the LED on the Pmod. If the Pmod has determined its location, the LED will stay off; otherwise, the LED will alternate between on and off every second.

To set up the demo you will need to open a serial terminal, such as TeraTerm, to see the data being printed out. Settings for the terminal will vary depending on your board.

For Zynq projects, apply the following settings:

  • Baud rate: 115200
  • Data bits: 8
  • Parity: none
  • Stop bits: 1

For MicroBlaze projects, apply the settings according to the AXI Uartlite IP configurations. These settings can be found by double clicking the AXI Uartlite IP in the block design and clicking the IP Configuration tab. By default, these settings are:

  • Baud rate: 9600
  • Data bits: 8
  • Parity: none
  • Stop bits: 1

When viewing the demo's output in certain terminals, the degree symbol in the latitude and longitude lines may not display correctly. A way to work around this is to log the terminal's output to a text file, which should display all characters correctly.

An example project on how to use the PmodGPS Hierarchical Block can be found here

Constraints

  • When using the Board Flow, no additional constraints are required.
  • When not using the Board Flow, template constraints for the Pmod_out port can be found in the imported "PmodGPS_*.xdc" file.