* mpc8xx memory mapped 16550A uart garbage
@ 2003-10-15 13:42 Lokesh Kumar
2003-10-15 14:21 ` Steven Scholz
0 siblings, 1 reply; 5+ messages in thread
From: Lokesh Kumar @ 2003-10-15 13:42 UTC (permalink / raw)
To: 'linuxppc-embedded@lists•linuxppc.org'
Hi,
I got the serial.c from DENX linuxppc_2.4._devel tree which has support for
16550A as memory mapped uart, and am using it as a module. I made
modifications to match my board. When I start it, it correctly recognizes
that I have a 16550A and at correct IRQ. However, when I open and send
something through the port (I just do cat>/dev/ttySe0), I get garbage on the
other side. My 16550 has a crystal of 3.6864MHz and the processor runs at
49MHz. I thought that this kind of garbage problem is generally due to baud
rate not set correctly. I see the divisor correctly calculated as
3686400/16/9600 = 24 and being sent to 16550. What else could I be doing
wrong?
Thanks
Lokesh Kumar
Wireless Matrix USA Inc.
703-262-4032
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: mpc8xx memory mapped 16550A uart garbage
2003-10-15 13:42 Lokesh Kumar
@ 2003-10-15 14:21 ` Steven Scholz
0 siblings, 0 replies; 5+ messages in thread
From: Steven Scholz @ 2003-10-15 14:21 UTC (permalink / raw)
To: Lokesh Kumar; +Cc: 'linuxppc-embedded@lists•linuxppc.org'
Lokesh Kumar wrote:
> Hi,
> I got the serial.c from DENX linuxppc_2.4._devel tree which has support for
> 16550A as memory mapped uart, and am using it as a module. I made
> modifications to match my board. When I start it, it correctly recognizes
> that I have a 16550A and at correct IRQ. However, when I open and send
> something through the port (I just do cat>/dev/ttySe0), I get garbage on the
> other side. My 16550 has a crystal of 3.6864MHz and the processor runs at
> 49MHz. I thought that this kind of garbage problem is generally due to baud
> rate not set correctly. I see the divisor correctly calculated as
> 3686400/16/9600 = 24 and being sent to 16550. What else could I be doing
> wrong?
Did you verify the baudrate using a scope to measure the bittime?
Steven
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 5+ messages in thread
* RE: mpc8xx memory mapped 16550A uart garbage
@ 2003-10-15 20:34 Lokesh Kumar
2003-10-16 7:08 ` Steven Scholz
0 siblings, 1 reply; 5+ messages in thread
From: Lokesh Kumar @ 2003-10-15 20:34 UTC (permalink / raw)
To: 'Steven Scholz', Lokesh Kumar
Cc: 'linuxppc-embedded@lists•linuxppc.org'
Hi Steven,
I did measure the bit width and that is around 104us, which is correct.
Anything else?
Thanks,
Lokesh
-----Original Message-----
From: Steven Scholz [mailto:steven.scholz@imc-berlin•de]
Sent: Wednesday, October 15, 2003 10:22 AM
To: Lokesh Kumar
Cc: 'linuxppc-embedded@lists•linuxppc.org'
Subject: Re: mpc8xx memory mapped 16550A uart garbage
Lokesh Kumar wrote:
> Hi,
> I got the serial.c from DENX linuxppc_2.4._devel tree which has support
for
> 16550A as memory mapped uart, and am using it as a module. I made
> modifications to match my board. When I start it, it correctly recognizes
> that I have a 16550A and at correct IRQ. However, when I open and send
> something through the port (I just do cat>/dev/ttySe0), I get garbage on
the
> other side. My 16550 has a crystal of 3.6864MHz and the processor runs at
> 49MHz. I thought that this kind of garbage problem is generally due to
baud
> rate not set correctly. I see the divisor correctly calculated as
> 3686400/16/9600 = 24 and being sent to 16550. What else could I be doing
> wrong?
Did you verify the baudrate using a scope to measure the bittime?
Steven
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: mpc8xx memory mapped 16550A uart garbage
2003-10-15 20:34 mpc8xx memory mapped 16550A uart garbage Lokesh Kumar
@ 2003-10-16 7:08 ` Steven Scholz
0 siblings, 0 replies; 5+ messages in thread
From: Steven Scholz @ 2003-10-16 7:08 UTC (permalink / raw)
To: Lokesh Kumar; +Cc: 'linuxppc-embedded@lists•linuxppc.org'
Lokesh,
> I did measure the bit width and that is around 104us, which is correct.
> Anything else?
Hmm. I suppose you tried sending only character again and again and verified
that your board is indeed sending this character over the lines by looking at
the scope...
Steven
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 5+ messages in thread
* RE: mpc8xx memory mapped 16550A uart garbage
@ 2003-10-16 20:14 Lokesh Kumar
0 siblings, 0 replies; 5+ messages in thread
From: Lokesh Kumar @ 2003-10-16 20:14 UTC (permalink / raw)
To: 'Steven Scholz', Lokesh Kumar
Cc: 'linuxppc-embedded@lists•linuxppc.org'
Thanks Steven,
The problem turned out to be my hardware fixture for testing 16550A. So, I
traced it and fixed and it works now.
Lokesh
-----Original Message-----
From: Steven Scholz [mailto:steven.scholz@imc-berlin•de]
Sent: Thursday, October 16, 2003 3:08 AM
To: Lokesh Kumar
Cc: 'linuxppc-embedded@lists•linuxppc.org'
Subject: Re: mpc8xx memory mapped 16550A uart garbage
Lokesh,
> I did measure the bit width and that is around 104us, which is correct.
> Anything else?
Hmm. I suppose you tried sending only character again and again and verified
that your board is indeed sending this character over the lines by looking
at
the scope...
Steven
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 5+ messages in thread
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2003-10-15 20:34 mpc8xx memory mapped 16550A uart garbage Lokesh Kumar
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