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Adc interfaceing problem on PDAP DMA

Question asked by vaibhav on Jan 21, 2012
Latest reply on Jan 23, 2012 by Harshit.Gaharwar

I am trying to interface one continnuous time sigma delta 16 bit ADC to ADSP21469 on PDAP (DAI pins). PDAP_CLOCK pin is provided with output clock signal from ADC (5MHz). PDAP_HOLD signal is grounded. i need to collect 1000 samples from ADC everytime. so my DMA counter is 1000 and modifier is 1. I except that after every 1000 samples DMA should generate an interrupt for the core to pick up samples for further processing. with 5MHz clock, i expect that the interrupt needs to be generated every 200 microseconds. (200ns * 1000 samples). with prsent code approach it is getting generated every 500ns. i am attaching code for your ready reference. this is confirmed by making one port pin high and low in PDAP ISR. please help me out to resolve the issue.