On 07-Jun-2000 [EMAIL PROTECTED] wrote:
> One question about the code for the regular Dragonball: you reference Port
> M bit 7 to get the status of the UART GPIO. This is fine, and I see it in
> the docs. Now also in the docs (pg 11-11 and 11-12) there is the "UART Baud
> Control Register" at 0xFFFFF902 in which bit 13 controls direction of GPIO
> and bit 14 gives the state of the pin (or lets you set the pin if made an
> output). Is there any difference between reading from the Port M data
> register vs. the UART register? I assume not, but...just curious.
It looks like it has a few functions. One thing it looks like reading the
GPIO Change Status bit on the UART will tell you if there has been a *change*
in the GPIO. I presume you would query that if you programmed it to
interrupt and wanted to know the source of the interrupt. But you are right
it looks like there is also a GPIO Status bit that supposedly is the same
value as the Port M bit.
I have limited understanding of the system, but the way I understand it you
can choose whether to interconnect internal peripherals to the CPU pins or
whether to leave the CPU pins as general purpose I/O. So I suppose if the
GPIO was set as connected to the UART then the two bits would read identical,
and on page 2-8 it does say that after a reset it becomes UART GPIO.
On the EZ I don't think it CSA1 is connected to the UART.
> Any other suggestions or warnings welcome, and thanks again,
Wear eye protection when you power it on! :)
/* Chris Faherty <[EMAIL PROTECTED]> */
/* Your Stock has crashed - you must now restart your system */
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