GPS Firmware API/Events

[mbooth101]

Major changes:

• Remove the graphical app portion, the firmware now runs in the background only
• Provide 3 API methods for getting the current position as a (lat, lon) tuple, ground speed in knots, and course in degrees from true north
• Add a GPSEvent type and emit events every time a location fix message is received from the GPS
• In both the API and the GPSEvent, when the fix is lost, the position value will be None instead of a tuple

Other fixes:

• Firmware version bumped to 2
• Add a character timeout to the UART configuration to improve the ability of uart.readline() to read a full line, and reduce parsing errors caused by reading partial lines
• Override background_task to manage sleep for longer between UART message bursts, to reduce the impact of the blocking UART timeout on other apps

[mbooth101]

In your Tildagon apps, you can then do this:

# Get the app running on the GPS Hexpansion
self.gps = get_app_by_vid_pid(0xCAFE, 0x1295)

Then use the API directly:

position = self.gps.position
speed_knots = self.gps.speed
speed_kmh = self.gps.speed * 1.852
course_degrees = self.gps.bearing

Or use the event system:

# Subscribe to GPS Events
if self.gps:
    eventbus.on(self.gps.GPSEvent, self._handle_gps_event, self)


def _handle_gps_event(self, e):
    """Method to handle GPS events """
    self.position = e.position
    self.speed_knots = e.speed
    self.speed_mph = e.speed * 1.151
    self.bearing = e.bearing

[mbooth101]

Note I wanted to add speed methods for common units, like mph, kmh, and metres/s, but there wasn't enough space in the EEPROM, so Tildagon app authors must do the conversion from knots. The conversion factors are as follows:

• mph = knots * 1.151
• km/h = knots * 1.852
• m/s = knots * 0.514

[mbooth101]

@Robotmad Will this repo be made redundant by the new Hexpansion firmware manager app that has been added to the Tildagon? https://github.com/emfcamp/badge-2024-software/blob/main/modules/firmware_apps/hexpansionfw.py

[mbooth101]

Note this is the firmware I used to develop my Speedo app against: https://github.com/mbooth101/emf-speedometer

[Robotmad]

background API based GPS hexpansion software - Note this has NO UI.