MAX10 ADC Sampling Issue after Power On

Hi,

I'm using a MAX10 (10M05DAF...) with a Nios 2 Processor. For the ADC the "Modular Dual ADC Core Intel FPGA IP" is used. Under some circumstances the sample_store registers never get filled with ADC values (all 0x00). Probably the ADC Sequencer does not run or has a problem.

Sometimes, everything works properly. To reach one of the mentioned "states" a reboot and reprogramming is required since we are running everything from volatile memory.

Facts:

- the VCC_3V3_Good signal is used as main reset_n and is high 1 ms before the VCC_2V5 is ready

- Bank 1A (ADC bank) is supplied by VCC_2V5

What did I notice?:

- I tried different initialisation sequences in software and sometimes after a reboot the software got stuck in this loop:

(function: adc_recalibrate(SEQ_BASE))

- I tried to delay the VCC_2V5 for about 100 ms on a "good tested" HW and couldn't reproduce the ADC issue. The 1 ms delay of the power supplies does not seem to be the cause.

Thank you for your help.

Cheers, Sven