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Altera_Forum's avatar
Altera_Forum
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11 years ago

IORD and IOWR issues

Hello there, I am struggling to understand a simple write and read with the nios processor. With qsys, I have setup a simple testcase where a nios (e) with no cache and a PIO are connected...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
11 years ago

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Afterwards, with eclipse program, I do a

IOWR(PIO_BASE,0,0xA);

printf("%X ",IORD(PIO_BASE,0));

I was expecting that "10101" in binary from a IOWR of 0xA.

However, it reads "0xA".

--- Quote End ---

Make sure Nios doesn't perform a cache access instead of the actual IORD access.

Flush the cache between the two instructions or force IORD to be uncached by setting address bit 31.