We bought a couple of ZED-F9P boards from Sparkfun and have been testing them.
We have been seeing a problem with them powering up, that is, sometimes they power up just fine but other times they just won’t come up properly. The issue sounds like this one: viewtopic.php?f=116&t=50872&p=207662&hilit=pps#p207662
We are powering them up via USB, and when they don’t power up correctly we see this in dmesg on linux:
[748579.524199] usb 3-1.7.1: new full-speed USB device number 15 using xhci_hcd
[748579.649377] usb 3-1.7.1: device descriptor read/64, error -32
[748579.861431] usb 3-1.7.1: device descriptor read/64, error -32
[748580.260162] usb 3-1.7.1: new full-speed USB device number 16 using xhci_hcd
[748580.381539] usb 3-1.7.1: device descriptor read/64, error -32
[748580.593411] usb 3-1.7.1: device descriptor read/64, error -32
[748580.700351] usb 3-1.7-port1: attempt power cycle
[748583.016175] usb 3-1.7.1: new full-speed USB device number 17 using xhci_hcd
[748583.024860] usb 3-1.7.1: Device not responding to setup address.
[748583.244853] usb 3-1.7.1: Device not responding to setup address.
[748583.456271] usb 3-1.7.1: device not accepting address 17, error -71
[748583.748289] usb 3-1.7.1: new full-speed USB device number 18 using xhci_hcd
[748583.756997] usb 3-1.7.1: Device not responding to setup address.
[748583.976901] usb 3-1.7.1: Device not responding to setup address.
[748584.188155] usb 3-1.7.1: device not accepting address 18, error -71
[748584.188348] usb 3-1.7-port1: unable to enumerate USB device
We’ve tested this on different machines and with different cables, so the problem does not seem to lie there.
There is also no communication through the UARTs or I2C.
In a successful powerup the PPS light is on for a bit and then turns off until PPS sync is acquired and then it starts blinking.
In this failure mode the PPS light is solid on along with PWR and FENCE.
When they start behaving this way, they seem to do so repeatedly, i.e. if I disconnect it and reconnect, it just comes up the same way. Then maybe the next day it works fine.
Based on that, once the board got to this state, we tried to drain the RTC battery using a resistor, and when powering the GPS after that it starts normally.
There’s also another startup failure mode. In this one, the PWR and FENCE lights are on, and the PPS light slowly blinks (on for 1s off for 1s, maybe?) for 10-20 seconds before turning off, then RTK turns on and after a GPS signal is acquired PPS starts to blink normally. When this happens it seems that UART communication works, but USB does not. We get this message:
[2157536.030140] cdc_acm 1-1:1.0: failed to set dtr/rts
Power cycling the GPS usually fixes this problem, but that is far from ideal.
We are powering the unit through USB, and have PPS and UART1 and UART2 connected to a Toradex Colibri IMX7 along with the USB.
Does anyone have any idea what may be causing this and/or have any solution to it?