I'm trying to read/write between a Mega16L and ST's M25P40 extenal
Flash memory. Both are running at 3.3V.
When I do a write instruction, the serial output of the flash stays
low, which is fine. But when I do a read instruction, the serial
output pulses high and then exhibits capacitive decay, and does not
look like a digital signal. Here's what the output of the flash chip
look like when there is no load (not connected to microprocessor). It
seems to go high for the duration of the chip select signal and then
decays exponentially:
http://www.zehao.com/temp/spiflash_miso.jpg
Here's the corresponding chip select signal (0 means chip is selected):
http://www.zehao.com/temp/spiflash_select.jpg
If I connect the output pin to the AVR, it becomes a flat ~2V signal.
I've tried 3 different chips and they all do the same thing. Can
anyone give me an advice or hazard a guess as to why this is happening?
_______________________________________________
AVR-chat mailing list
[email protected]
http://lists.nongnu.org/mailman/listinfo/avr-chat
