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a slower flash

Perla Grochowski

i purchased a flash module
am29f040b-90J

its access time is 90ns, but the microcontroller has 80/60ns instruction cyle.

Can I use this flash with the microcontroller? Or is it preferrable that I purchase a faster flash? The way I'm talking to flash is via a gui called BootLoad, but I haven't been able to see the program run purely thru flash. Which leads to my next question.

I'm experimenting with the sample code called "Blinky". I figure that if the code is in flash, then I should be able to power up the MCB167NET and automatically see the led lights turn on as the "blinky" program would have it. Has anyone gotten this to work, or know what hex values to input in that gui for:
BUSCON0
SYSCON0


I've been reading the Manual and have determined that BUSCON0:0XC69F and
SYSCON0:0X887. I show that the program was loaded succesfully and then am prompted to "reset processor and start program". So I hit reset, but don't see the led lights turn on and off as the "blinky" program would have them do.
So, perhaps my hex numbers are wrong? Or, what am I doing wrong?
Are there any other registers I also need to change?

I know these are a lot of questions. If you know the answer to one of them, it would help me some. Any help is good.

Thank you all in advance.

  • 0

    The answer to your first question is: yes, absolutely. Many of characteristics of the external bus of the microcontroller are programmable. Look in the microcontroller manual for the words 'memory cycle time'. You should extend the cycle time by 1 waitstate (@25MHz CPU clock) in order to work with your flash chip (of course, this will slow down program execution a bit).
    As for the rest of the questions, I haven't worked with MCB167NET, but there was a time when I had to start working with a C166-based board. I read the microcontroller manual and studied schematic diagram of the board in the first place, before turning it on. The C167 microcontroller is not very straightforward in configuration (which is the downside of it's flexibility), so knowledge of hardware would always be useful.

  • 0

    The AM29F040-90 requires BUSCON0 to be set to 0xC40D if the controller is running at 25MHz.

    HHK