Sources of error - InnoRoute/RealtimeHAT GitHub Wiki

What to do if something is not working?

FPGA stops working during operation

  • check the chip temperature using INR_FPGA_status. (If the temperature was trigger the threshold of 75°C, you have to reset the chip first to enable the FPGA interface again)

Error on Register access

No SSH-connection via RT0 and RT2

  • The HAT reduces the available MTU to 1400 bytes, it does no segmentation of incoming packets. Make sure your ssh-client don't send oversized packets. sudo ifconfig <your-interface> mtu 1400

No connection to FPGA

  • The configuration of the FPGA was not successful if it is not responding on the SPI interface. For testing you can manually read a part of the FPGA's device-id with sudo /usr/share/InnoRoute/INR2spi 0x3C0C0200 if the return value is 0 something is wrong with your FPGA connection.

possible causes

Raspberry not booting

If you attach a serial interface to the root-shell of your RPI you might see undervoltage-warnings and maybe the kernel stops booting during attaching the root-partition from MMC.

possible causes

  • as you know for sure, the raspberry is picky in point of its power source. Your should test other usb-cables (yes sometimes its just the cable, especially cheap ones) and other power sources.
  • you can order the power-adapter with you HAT ;)
  • we suggest to use the official RPI4 power adapter

Problems with outgoing https requests:

  • The raspberry hardware and system clock are synchronized vie PTP. If the received time is to far away from now https requests may fail. As hotfix, the ntp-deamon can be enabled until next reboot: sudo service systemd-timesyncd start

Known bugs

  • packets from external RT2 arrive at internal RT0
  • the HAT supports just 1GbE for now, other Linkspeeds are currently not supported