Question to 16x5x driver users

Question to 16x5x driver users

[Alexander Aganichev]

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.

-- 
WBR, Alexander

Re: Question to 16x5x driver users

[Guennadi Liakhovetski]

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.

Thanks
Guennadi
---------------------------------
Guennadi Liakhovetski, Ph.D.
DSA Daten- und Systemtechnik GmbH
Pascalstr. 28
D-52076 Aachen
Germany

Re: Question to 16x5x driver users

[Gary Thomas]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

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
fix.

Alexander, please provide a proper patch, along with ChangeLog
entry to ecos-patches@ecos.sourceware.org.  We'll review and
apply as appropriate.

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