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Altera_Forum's avatar
Altera_Forum
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15 years ago

How to connect UART and DMA?

In the document "Embedded Peripherals IP", I find following paragraph: "The UART core's Avalon-MM interface optionally implements Avalon-MM transfers with flow control. Flow control allows an Aval...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

Still no solve.

1. My developing software is Quartus II 10.1.

2. I used a scope to watch the wave of TX pin. If I write the UART writedata register directly, I can see the right wave. However, when I use DMA to trans this data, the TX will be hold high.

3. When debug on the hardware, I find the dma status will go to 0x03 soon after the alt_dma_txchan_send is run. But still no wave appears on TX pin. The UART writedata register is never changed.

4. When I use signaltap II to watch the dma signals, "writedata, write_n, waitforrequest, writeaddress", all value is what I want. But there is one question, the data rate is half of the cpu clk. I don't believe a writting operation to a UART writedata registor can be so fast. However, the writeaddress is do the UART TXDATA registor.

I am sure the connection of UART, SRAM and DMA is right, and I am so puzzled. Could anybody help me???

Thank your very much!!