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Flash Interface with AT91RM9200

Started by MaheshS December 6, 2005
Hi,
  I am doing a prototype baord based on AT91RM9200.I am planning to use 
Intel Strataflash memory (E28F640J3A)on the board.This flash memory is
having a program enable input.How can i connect this to the processor,
while interfacing?If anyone is using the same flash, please suggest.
  Also I would like to understand how does the USB_DP_PUP signal
enable/disable the pull-up resistor on DP?(Ref: Interfacing USB Device
peripheral-AT91RM9200 datasheet)
Best regards,
S Mahesh.

MaheshS wrote:
> Hi, > I am doing a prototype baord based on AT91RM9200.I am planning to use > Intel Strataflash memory (E28F640J3A)on the board.This flash memory is > having a program enable input.How can i connect this to the processor, > while interfacing?If anyone is using the same flash, please suggest.
The VPEN pin is used to lock/unlock the device globally for writing. If you wish to have some certainty that the device may not be written to in a spurious manner (during startup/shutdown, for example), connect this pin (with a pulldown of about 100k) to an IO port bit. The pulldown will ensure VPEN is invalid until the processor starts up and initialises the port bit, preventing spurious writes. If you believe there should be no problem, pull the line to Vdd through 100k. This will make the device unlocked (at that level, anyway) at all times. Note you still have to write to the device to unlock blocks.
> Also I would like to understand how does the USB_DP_PUP signal > enable/disable the pull-up resistor on DP?(Ref: Interfacing USB Device > peripheral-AT91RM9200 datasheet)
The USB spec can clear this up. An upstream (slave) port has to signal it is present. It does this by pulling the DP line high through 1.5k, 1%. Releasing this line permits the downstream (host) to pull *both* lines low (through 15k). With both lines low, no active device is assumed to be attached.
> Best regards, > S Mahesh.
Cheers PeteS
>MaheshS wrote: >> Hi, >> I am doing a prototype baord based on AT91RM9200.I am planning to
use
>> Intel Strataflash memory (E28F640J3A)on the board.This flash memory is >> having a program enable input.How can i connect this to the processor, >> while interfacing?If anyone is using the same flash, please suggest. > >The VPEN pin is used to lock/unlock the device globally for writing. If >you wish to have some certainty that the device may not be written to >in a spurious manner (during startup/shutdown, for example), connect >this pin (with a pulldown of about 100k) to an IO port bit. The >pulldown will ensure VPEN is invalid until the processor starts up and >initialises the port bit, preventing spurious writes. If you believe >there should be no problem, pull the line to Vdd through 100k. This >will make the device unlocked (at that level, anyway) at all times. >Note you still have to write to the device to unlock blocks. > >> Also I would like to understand how does the USB_DP_PUP signal >> enable/disable the pull-up resistor on DP?(Ref: Interfacing USB Device >> peripheral-AT91RM9200 datasheet) > >The USB spec can clear this up. An upstream (slave) port has to signal >it is present. It does this by pulling the DP line high through 1.5k, >1%. Releasing this line permits the downstream (host) to pull *both* >lines low (through 15k). With both lines low, no active device is >assumed to be attached. > >> Best regards, >> S Mahesh. > >Cheers > >PeteS > >
Hi Thanks for the suggestion. If we are using a single flash memory IC, is it possible to have a glueless connection? in that case, can we connect the chip select signal from controller directly to CE0 (with CE1 and CE2 connected to GND)? Regards, S Mahesh.