AT28C64, 28C64 Datasheet, 28C64 64K ns Parallel PLCC EEPROM Datasheet, buy 28C 28C64 datasheet, 28C64 pdf, 28C64 data sheet, datasheet, data sheet, pdf, Atmel, 64K 8K x 8 CMOS E2PROM. 28C64 64K (8K x 8) CMOS E2prom with Page Write and Software Data Protection Features. Fast Read Access Time ns Automatic Page Write Operation.
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I’d recommend following that same sequence and also change your write sequence to follow the diagram on the following page. BTW, if the chips are equipment pulls as opposed to new parts, it’s possible that the “software protection” feature has previously been enabled.
Thanks for the info. I am using the Xicor 28C64AP chip datasheet. Email Required, but never shown. That will make the remainder of your code much more readable.
If dqtasheet has, you’ll need to wire up all your address wires in order to disable it. I have edited my question. Here is my code, sorry if it seems too cluttered: The chips are new, and I actually have two from two different manufacturers. When the timer expires, an internal write cycle is triggered and additional writes before it completes.
The same diagram shows CE being asserted followed by OE for a read cycle. I have tested an earlier version of the above program with a static RAM chip and everything works great.
28C64 Datasheet pdf – 64K 8K x 8 CMOS E2PROM – Atmel
I added ms delays between every control pin change and made sure the order was consistent with the datasheet, datasgeet still no luck. I don’t really like the design, but my guess is that it was trying to be compatible with an earlier part where one could write locations one at a time and just wait after each one. Post as a guest Name. Thanks for the response, supercat.
Since I am only using the first three address pins, the rest are tied low. Also, I would suggest that you should write a writebyte procedure which sets all address and data wires to output and puts proper values on datashert, ensures WE and OE are deasserted, asserts CE, asserts and release WE, and releases CE, and a readbyte procedure which sets all address wires to output and puts proper values on them, sets all data wires to input, asserts CE and OE, samples all the data wires, and releases CE and OE.
The timings for this particular EEPROM aren’t super-critical, but it has a timer which starts when the first byte is written and gets reset if another byte is written before it expires. Home Questions Tags Users Unanswered. Initializing pins for write I have tied the top 10 address bits low and am only using the first 3 for now.
Sign up or log in Sign up using Darasheet. Mar 26 ’13 at I wrote a program for the Arduino Uno that writes data to the first 4 addresses and then reads the data back.
Looking at the datasheet on page 12 it shows a timing diagram and Chip Enable Access Time can be up to nS. All behave the same. Here is the serial output. You have not indicated that you are doing anything with them?