RedPitaya continuously rebooting when no 125 MHz ADC clock

[abregnsbo]

In my application I need to slave the 125 MHz ADC clock to the output from the Zynq (R25/R26 removed, R27/R28 22 ohm).

However, with this modification the Red Pitaya continuously reboot. Booting progresses normally: the yellow SD card activity LED flashes vigorously and the red CPU heartbeat has a 0.8 Hz double-blink. Then the yellow SD card turns on permanently, while the red CPU heartbeat stops blinking. This persists 3-4 seconds and then the Red Pitaya reboots.

As I understand it the PS runs on a separate PS_CLK. Why should it care if PL does not get its 125 MHz clock ? Who controls the red CPU heartbeat LED ? Is some Linux software launched that tries to access the PL, causing the cpu to hang because the AXI bus to the PL hangs ?

I have tried to disable programming of the PL by modifying sbin/startup.sh, but that did not help.

At one point the Red Pitaya booted successfully, and I was able to login with ssh. When I did a "monitor 0x40000030" command to read from a memory mapped PL address, I saw the same behaviour: yellow SD card turning on, red CPU heartbeat stop flashing, and reboot after a couple of seconds.

[abregnsbo]

During a normal boot the red CPU heartbeat blinks for 14 cycles. The Red Pitaya that reboots, hangs after 6-7 heartbeat cycles. I surmise that halfway during booting some program or driver reads from the PL address range.

[redpitaya]

Dear abregnsbo,

Thank you for contacting us through the forum. I apologise for the late reply.

The slave boards need a clock applied through the Sata extension connectors in order to function.

I am sorry to inform you that we cannot help further due to the board receiving hardware modifications not performed by the Red Pitaya team. There is a clear warning on the webpage next to the description of the possible modifications.

Here is a copy of the warning:
"We do not advise altering the board because users have reported problems after doing so. Every board made has undergone rigorous testing, which cannot be claimed for modified boards. Any non-Red Pitaya hardware modification will void the warranty, and we cannot guarantee support for modified boards."