We have a recent batch of the F9R GPS (SparkFun GPS-RTK Dead Reckoning Breakout - ZED-F9R (Qwiic) - GPS-22693 - SparkFun Electronics). Once it has been powered on for a while, they dont seem to enumerate on USB. Are there any issues with the F9Rs where they wont enumerate when warm ? How much USB current do they consume on power up ? Is there anyway to limit USB current on startup ?
No, no known issues there…how are the devices being powered? How hot/warm are we talking lol? Are you using a known-good cable?
Have you noticed any pattern to anything (timing, temp, position, etc)?
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They are powered by the USB port. We have tried multiple USB cables and multiple CPUS. The issue may be on our CPU host USB side. The GPS, any time it comes up, is fine so far. Pattern is start cold, GPS runs. Start warm and GPS does not enumerate on the USB bus. Thus it is important to know the USB current the board draws on startup, at steady state and if it can be reduced by configuration. It happens under multiple firmware versions for the F9R. Its takes maybe 15 minutes warm or more.
The product page says:
- Current: ~85mA to ~130mA (varies with constellations and tracking state)
So maybe ~2-3x that for startup (with hotstart)
Can you test with a different PC?