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Altera_Forum's avatar
Altera_Forum
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16 years ago

Nios instability

Hello, I'm using nios II processor with a high_res_timer for different test before continuing my project. The test i'm trying to do is to generate on a pin a square frequency with a 400µs period...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

What is the amount of instability you observe in the square wave?

I have a similar situation for a 1kHz wave and have very good stability, far below 1us.

I use IOWR_ALTERA_AVALON_PIO_DATA, too, so I think this is not your actual problem. I'd rather think it's due to alt_timestamp function or to your nios/sopc configuration (as DSL suggested). Infact, I don't use alt_timestamp but I have tried the following solutions, both achieving similar stability:

- pio controlled in timer interrupt service

- polling directly the timer count register until switching condition is achieved, in the same way you did through alt_timestamp.

Cris