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Topic: Trouble with SPI read/write to 23K256 SRAM chip (SOLVED) (Read 2 times) previous topic - next topic

SurferTim

I think Adafruit carries the 74LVC245. You should be able to get the 74LVC125 from any electronics distributor like Digi-Key or Mouser.

chrisharrington

Thanks, I'll give the 74LVC245 a shot because I can get it in a DIP package. I can only find the 74LVC125 in surface mount (I don't do surface mount yet).

SurferTim

You are welcome!  :)

If you would do me a favor now. When you get the new logic level converter, please post what SPI bus speed it will handle. The default is SPI_CLOCK_DIV4.


chrisharrington

I'll do that. I just ordered a few of those from RS (they ship next day here in Japan), so I should be testing them in the next couple of days.

SurferTim

#24
Sep 28, 2013, 04:32 pm Last Edit: Sep 28, 2013, 05:07 pm by SurferTim Reason: 1
Bear in mind, you can really improve performance of that SRAM by using the other modes of operation. Page 6 of the Microchip datasheet. Read about the page and sequential modes. That should just about double the R/W speed.
http://ww1.microchip.com/downloads/en/DeviceDoc/22100E.pdf

edit: My maths sucks today. Make that almost 4 times faster.
One byte instruction - two bytes address - one data byte
One byte instruction - two bytes address - one data byte
One byte instruction - two bytes address - one data byte
One byte instruction - two bytes address - one data byte
versus
One byte instruction - two bytes address - 1st data byte - 2nd data byte - 3rd data byte - 4th data byte - ...

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