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Re: Question to 16x5x driver users

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Guennadi Liakhovetski wrote:
> On Mon, 18 Jun 2007, Alexander Aganichev wrote:
>> I found that driver not transmit anything in interrupt driving mode
>> unless I made the following patch:
>> Index: packages/devs/serial/generic/16x5x/current/src/ser_16x5x.c
>> ===================================================================
>> RCS file:
>> /cvs/ecos/ecos/packages/devs/serial/generic/16x5x/current/src/ser_16x5x.c,v
>> retrieving revision 1.14
>> diff -u -r1.14 ser_16x5x.c
>> --- packages/devs/serial/generic/16x5x/current/src/ser_16x5x.c	27 Nov
>> 2006 13:59:50 -0000	1.14
>> +++ packages/devs/serial/generic/16x5x/current/src/ser_16x5x.c	18 Jun
>> 2007 12:21:30 -0000
>> @@ -516,6 +516,7 @@
>>     HAL_READ_UINT8(base+REG_ier, _ier);
>>     _ier |= IER_XMT;                    // Enable xmit interrupt
>>     HAL_WRITE_UINT8(base+REG_ier, _ier);
>> +    (chan->callbacks->xmt_char)(chan); // <<<<<<
>> }
>> // Disable the transmitter on the device
>> Am I right to make this change or I just missed another process that
>> should call xmt_char? I'm using LPC2294 based board and use this
>> driver for the UART1.
> It looks like eCos uses the usual UART sending procedure - enable tx-empty 
> (IER_XMT) interrupt and return, then the interrupt should trigger as soon 
> as tx is empty / tx fifo can take more data, and you write more data in 
> your interrupt handler to the port. The fact it doesn't work for you means 
> most probably that you're not getting tx-empty interrupts, and, perhaps, 
> no UART interrupts at all.

In my experience, this [incorrect] behaviour is not all that
uncommon.  I think that a CDL controlled option to enable this
initial "push" (although I'd call it 'priming') is the correct

Alexander, please provide a proper patch, along with ChangeLog
entry to  We'll review and
apply as appropriate.

- --
- ------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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