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Serial Drivers Confusion

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Serial Drivers Confusion

Postby tassman » Tue Feb 28, 2006 4:18 pm

Hi all!

I'm currently working on a Total5200 board with QNX 6.2.1 and I'm wondering what's the maximum baudrate through the UARTs. I know that by hardware the limit is set to IPBI frequency / 32, that is 132MHz / 32 = 4.125 Mbps. But first I'm kinda confused by the existance of two serial drivers: devc-psc-uart-total5200sdp + devc-16c654-total5200sdp. What is the difference of those two? bootup.serial.ksh just uses devc-16c654-total5200sdp. What's the devc-psc-uart-total5200sdp for?
Next, the parameters allow to set some clock values (-c on both drivers): Here I read something about 7.3728MHz for the 16c654, there I read something about the IPBI freq with divisors by 1 or 16. Where do I have to set what? How do these clocks relate to each other?

This was the long part of the question, the short version is: Is it possible to get a UART baudrate about 1Mbps with the QNX 6.2.1 drivers on the Total5200 and how?

Thanks for listening :)

Regards,

tassman
tassman
New Member
 
Posts: 1
Joined: Mon Feb 27, 2006 3:50 pm

Re: Serial Drivers Confusion

Postby Dave Green » Tue Feb 28, 2006 6:52 pm

The BSP for the Total5200 that was part of QNX 6.21 was actually
provided by Freescale (who were then Motorola). Since that time,
QNX has been providing our own BSPs for the various MGT5200
boards.

There are two different serial interfaces on the Total5200; one comes
from the PSC UARTs on the MPC5200 core (there is only one PSC UART
brought out to a D-9 connector on the Total5200 - PSC3), and the other
is a multiple 16550 compatible UART, from the Total5200's CPLD device,
and this is brought out to the eight D-9 connectors on the sides of the
Total5200.

I'm not sure about the PSC UART driver that Motorola provided, but the
currently shipping QNX PSC driver (devc-serpsc) does support up to the
maximum baud rate. If the Motorola driver also supports the maximum
baud rate, it should simply be a matter of providing the proper -b
option on the command line for the serial driver. The driver should
then calculate a divisor value of 1. Of course, whatever is connected
at the other end of the serial cable must also be capable of running at
this same baud rate.



tassman <Tassilo.Schuetz@3soft-dot-de.no-spam.invalid> wrote:
Hi all!

I'm currently working on a Total5200 board with QNX 6.2.1 and I'm
wondering what's the maximum baudrate through the UARTs. I know that
by hardware the limit is set to IPBI frequency / 32, that is 132MHz /
32 = 4.125 Mbps. But first I'm kinda confused by the existance of two
serial drivers: devc-psc-uart-total5200sdp +
devc-16c654-total5200sdp. What is the difference of those two?
bootup.serial.ksh just uses devc-16c654-total5200sdp. What's the
devc-psc-uart-total5200sdp for?
Next, the parameters allow to set some clock values (-c on both
drivers): Here I read something about 7.3728MHz for the 16c654, there
I read something about the IPBI freq with divisors by 1 or 16. Where
do I have to set what? How do these clocks relate to each other?

This was the long part of the question, the short version is: Is it
possible to get a UART baudrate about 1Mbps with the QNX 6.2.1
drivers on the Total5200 and how?

Thanks for listening :)

Regards,

tassman


--

David Green (dgreen@qnx.com)
QNX Software Systems Ltd.
http://www.qnx.com
Dave Green
 


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