Input overruns at 375K baud on ATSAMA5D3 Xpalined

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rambabureddi
Posts: 1
Joined: Wed May 27, 2015 3:00 pm

Input overruns at 375K baud on ATSAMA5D3 Xpalined

Wed May 27, 2015 3:29 pm

Hi,

i'm running linux kernel linux-at91-linux-3.18-at91 on ATSMA5d3 Xplained board.
This board(Slave module) is communicating on Baudrate 375000(I'm using USART1 in async mode) with Master. Master continiously sends command and slave should respond within 400micro sec. during receive packets i'm observing overrun errors (oe: 34 and increasing so on). I could observe "2 Input Overrun(s)" on debug console.
i have configured USART1 Tx in DMA mode and Rx in Noraml mode. reason to use Rx in normal mode is: Master sends frame start byte with MARK parity and remaining bytes on SPACE parity. As DMA is not reporting parity errors i haved configured Rx in normal mode.

Can any one suggest me on How to over come this input overruns.
blue_z
Location: USA
Posts: 1943
Joined: Thu Apr 19, 2007 10:15 pm

Re: Input overruns at 375K baud on ATSAMA5D3 Xpalined

Thu May 28, 2015 9:17 pm

rambabureddi wrote:Master sends frame start byte with MARK parity and remaining bytes on SPACE parity.
This reads like a hack to emulate 9-bit char frames using eight data bits with a parity bit.
Is that what you are doing?
FYI the Atmet USART has 9-bit capability.
rambabureddi wrote:As DMA is not reporting parity errors i haved configured Rx in normal mode.
Is "normal mode" supposed to be programmed I/O?
Did you try elevating the interrupt priority?

Regards

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