AVR to DataFlash interfacing

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OK, here's a problem I had with the Appnote AVR335 (Digital Voice Recorder using an AT90S8535 and a AT45DB161). The circuit given shows the same Vcc being given to both the DataFlash and the AVR, even though the AVR is a 5V part and the DataFlash is a 2.7V only part. What gives? Does the DataFlash have 5V tolerant I/Os? Please help!

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Hi Jim,

it's easy. You just have to choose the at45D161.It's a mistake in the appnote.
bye

Michael

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Thanks Michael. Now this means that I've got to spend *even* more money placing an order for the new chip... there must be a way, using level shifters (CD4050 maybe?) or something.

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OK, sorry this is not a part of the prev. mail, but here goes: if someone's on this list from Bangalore, India, please point me to some place where I could purchase an AT45D161 without waiting for four weeks. The local Atmel rep. has to import it from singapore, costing $$$ and lots of time. My project is due long before then, I desperately need the chip. My idea of using a CD4050 would probably not work again because the HCT versions of these are not available here, and non-HCT versions wont work at 8MHz.

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Hi Jim,

1.
you must power the AT45DB161 with 2.7V

2.
its output can connected directly, since it should meet the TTL specifications (high level = above 2.4V)

3.
its inputs connect also direct to the AT90S8535, but you must it use as open drain outputs in the following way:

- set the pin in the output register permanently 0.
- whenever you want to put out a 0, write an 1 to the bit in the direction register
- use external pull up resistors against 2.7V for 1 level.

This means, you must write the inverted output signal to the direction bit.
Also you can not use the hardware SPI. Use software SPI.

Peter