IOWR and direct adress access

Hi hugeant,

> I do not know what different between these two way.

When you use "direct access" you end up using stx/ldx instructions. When you use

the IOWR/IORD macros, you get the stxio/ldxio instructions. The "io" instructions

bypass the data cache.

> but the data never send out from the uart

Do you mean you didn't see any data on your terminal? ... or nothing was

transmitted at all? Your terminal software simply may not be displaying NULL

for example -- but the transmission may actually be occurring.

If you're using a data cache, you should flush prior to calling alt_dma_txchan_send.

The last time I looked at that code, it didn't flush the cache for you ... so it's your

program's responsibility. You might be transmitting all NULL, since your buffer data

is still in the cache (it was never written back).

Regards,

--Scott