RE: mpc8xx memory mapped 16550A uart garbage

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


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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


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