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Altera_Forum's avatar
Altera_Forum
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20 years ago

IOWR and direct adress access

I can use IOWR,IORD and direct address access to operate SDRAM, But i can not use address to access Uart, for example: 1. use address alt_u8 * UartTxAdr; UartTxAdr = UART0_BASE+1; ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
20 years ago

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originally posted by jasondiplomat@Oct 22 2005, 05:20 AM

any "i/o variables" should be qualified as volatile[/b]

so : volatile alt_u8 * UartTxAdr

This prevents the optimiser from tuning the code out (because it will detect that nothing is "reading" the location).

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[/b]

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Thanks for you reply ,JasonDiplomat.

you means that the DMA controller also effected by "volatile" ??