why the spi of the am3352 has idle time?

zuobing huang

Intellectual 300 points

Other Parts Discussed in Thread: AM3352

condition：The d-cache and I-cache of the am3352 is on. The SPI use DMA。

the CLK is 24Mhz，so one Byte is 333n.

The idle time is 208ns-20ns=188ns。

Why the spi of the am3352 has idle time?I think the spi must send out contimous wave.

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

There are internal latencies that accumulate over the interconnects. What software are you using?

0 zuobing huang over 9 years ago in reply to Biser Gatchev-XID

Intellectual 300 points

Dear Biser
I use StarterWare.The test go on when the system start up.When the SPI Dma operate,the A8 wait.So the system has very low load.
zuobing huang

0 Wolfgang Muees1 over 9 years ago

Genius 3685 points

- Use the TURBO mode

- Use the SPI FIFO.

Note that TURBO and FIFO are only available for ONE SPI interface at a time.

0 zuobing huang over 9 years ago in reply to Wolfgang Muees1

Intellectual 300 points

Use the Turbo mode

Use the SPI FIFO(one byte).

The SPI idle time is from 60 to 120ns.

if I use FIFo >1 and the DMA,I fail.

0 Yaoming Qin over 9 years ago in reply to Biser Gatchev-XID

TI__Expert 3280 points

Hi Biser,

Mr. Huang is my customer.

Could you help to check internally to confirm his findings?

Thanks!
Yaoming

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why the spi of the am3352 has idle time?