Re: Setting up registers on PXA270?
- From: "Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT com>
- Date: Tue, 29 Apr 2008 08:48:40 -0700
Then that's a characteristics of your Platform/BSP. That's where the code
to configure the memory region where the DSP will be mapped should appear.
I'd probably do it in the bootloader myself, but that's not mandatory. You
could do it in or from a call made in OEMInit() in your platform code.
If you are *also* using GPIO to interface to this hardware, the
initialization of the direction and initial state of those pins should, to
my way of thinking, also be set up in the same place. Since all of this
stuff is completely specific to your hardware design, you'd never use the
driver anywhere else, but I prefer to have those things set in a central
location where you can document the connection between the schematic for the
hardware and what you're setting up the processor to do.
Paul T.
"Steve Conner" <connermcsteve@xxxxxxxxxxxxxx> wrote in message
news:a06a7353-5003-44ca-b6dd-a22f5aa49e4a@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi FoolBlah, thanks for the reply...
I'm mapping the DSP's host port into memory using the PXA270's VLIO
feature, roughly following the guidelines in the Intel app note for
connecting an IDE hard drive.
To make this work, I need to change the direction, level and function
of a GPIO pin (enabling the relevant chip select line) and change one
of the memory controller registers to turn the VLIO on. I've tried
this through RedBoot and seen the relevant things toggling on an
oscilloscope.
My only worry is that the BSP already includes a driver for the GPIO
pins that might get in my way. If it loads before my driver, does that
mean it could stop me accessing the registers? And if it loads after
mine, it could clobber the changes that I've made.
steve
On Apr 29, 12:04 pm, FoolBlah <foolb...@xxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:
Generally, a good practice is to setup the peripheral controller, GPIOs,
etc.
that you will be using in a specific driver at driver init time. This
cannot
always happen, but it makes debugging easier (for you and someone else
that
might look at the code someday) if you can architect it in this fashion.
What you are thinking is correct and yes you can use MmMapIoSpace() from
the
DDK to map the memory space. There is a possibility that what you plan
on
doing may clobber some other user of these peripherals. Do a search in
the
BSP for the various peripherals that you plan on using to be sure when
you
configure them you do not break something else in the process.
What controller/peripherals do you plan on utilizing?
.
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