UART DMA

Hello everybody,

Now I'm working for a project which is need data transfer from UART. My data are too many so the transfer speed is too long and make the processor stop working and cannot continue the calculation. I want to make the data from UART is saved directly to the RAM using DMA. Is that possible? Is there any tutorial to make it?

Sorry for my English, Thx before

0 bhfletcher over 10 years ago

I'm not aware if it is possible to DMA PS UART data directly to the DDR3. I don't think so. I have not seen any discussion or tutorial that shows how to do this.

If may be possible to put the UART controller in the PL and then design a wrapper around that PL function and DMA that into DDR3, but again, I have not seen that anyone has already done that.

Bryan
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0 Former Member over 10 years ago

thx for the answer. I also had looking for the example and cannot found anything.
I got an idea to get the manage the uart using the second core of cortex A9, so the first core processor still can do the calculation. is that possible?
can both of the core share the same RAM?

thx before
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0 Former Member over 10 years ago

Are you using interrupts? The built-in UARTs each have an 8 byte FIFO... it would be interesting to know how fast your data is to fully saturate a CPU?
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0 bhfletcher over 10 years ago in reply to Former Member

Both cores do share the same RAM, so using the one processor to communicate over UART and populate the RAM while using the other processor to read the RAM and perform calculations would be a possibility. Avnet covers a simple dual-processor example in the Vivado 2013.3 Zynq Software Development Speedway. This is available through your local FAE now and will soon be available online here.
Bryan
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0 Former Member over 10 years ago

Yes I'm using interrupt. The data is about 400 char. With baudrate 115200 I'll get about 34 ms. The data came every 1 s. But I need to a calculation every 25ms. I'll miss 1 sample every time the data come.
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0 Former Member over 10 years ago in reply to bhfletcher

Thx for the answer. It helps a lot. But I'm from indonesia and I think there is no local fae right now in my country. Is there any other tutorial show me how to use the second core?
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0 Former Member over 10 years ago

Can you guard the critical part of your 25ms routine against interrupts; the FIFO is 8 characters deep; you have a window of about 600 microseconds before you lose serial data?

Maybe I am reading it wrong?
See "Figure 19-9: UART RxFIFO and TxFIFO Interrupt"
Zynq-7000 AP SoC Technical Reference Manual
UG585 (v1.7) February 11, 2014
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