Re: [ECOS] Double buffers using US_RPR and US_RCR

[Laurent GONZALEZ <laurent dot gonzalez at silicomp dot fr>]

On Fri, 24 Oct 2003 13:19:33 +0200
Magnus Nilsson <man@lundinova.se> wrote:

> Hi,
> 
> I'm doing speed tests using double receive buffers and US_RPR/US_RCR.
> I don't have access to any flow control, and I'm losing a byte of
> every now and then, regardless of baudrate.
> Presumably this happens when I receive a byte just as I'm switching
> buffers.
> 
> My buffer switching routine looks like this (it runs often enough not
> to get any overruns):
> US_RCR = 0; // disable transfer
> current_chars = US_RPR - (uint32)rx_buffer_1; // see how many chars 
> there are in the buffer
> US_RPR = (uint32)rx_buffer_2; // receive in the other buffer, as we're
> 
> going to read the first one
> US_RCR = BUFFER_SIZE; // re-enable transfer
> 
> I have experimented with using:
> if ((US_CSR & US_TIMEOUT) == US_TIMEOUT) {
>  // switch buffers
> }
> which greatly increased the accuracy, but I'm still losing ~1 byte
> every ~100kB.
> 
> Do you have any ideas on how to switch buffers without using flow
> control?
> 

Hello Magnus,

This is a known issue in atmel's core. I discussed about that with
ATMEL's engineer and we together found the way to make it work without
any char loss.
Have a look on my driver. I recently contributed in the ecos-patches
mailing list.

regards,

-- 
GONZALEZ Laurent
Silicomp Research Institute
Tel: 04 76 41 66 98

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