Author Topic: Read/Write EEPROM Fairchild NM93C46 with Buspirate  (Read 724 times)

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Offline MartinMartTopic starter

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Read/Write EEPROM Fairchild NM93C46 with Buspirate
« on: May 28, 2023, 08:01:11 pm »
I know the Buspirate is quite an old tool, but if someone still has experience with it, I would really appreciate your help.

I try to read data from an EEPROM with it (Fairchild NM93C46) Datasheet: https://pdf1.alldatasheet.com/datasheet-pdf/view/54268/FAIRCHILD/NM93C46N.html
I also found this tutorial end set everything up the same way: http://dangerousprototypes.com/forum/index.php?topic=7112.0

VCC -> 5V
GND->GND
CS->CS
SK->CLK
Do->Miso
Di->Mosi
3V -> Pullup-restistors


I then used the 3Wire mode set up as in the tutorial above.

When i try the command  [-^^_^ _^:7 r] or ]-^^_^ _^:6 r:1024[ or anything similar I always get 0xFF.

Really appreciate any help and guidance. :D
« Last Edit: May 28, 2023, 10:22:03 pm by MartinMart »
 

Offline mon2

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Re: Read/Write EEPROM Fairchild NM93C46 with Buspirate
« Reply #1 on: May 29, 2023, 11:23:50 pm »
Swap the DO and DI connections and try again.
 

Offline MartinMartTopic starter

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Re: Read/Write EEPROM Fairchild NM93C46 with Buspirate
« Reply #2 on: May 30, 2023, 09:00:28 pm »
Hi, thanks for your help, then the output switches to 0x00...
Edit: I checked all connections again with a multimeter, and then I suddenly received an output of some HEX values and the rest 0xFF, but re-running the same command [-^^_^ _^:6 r:1024] gave me different values? Shouldn't the read output stay the same all the time?
« Last Edit: May 30, 2023, 09:48:20 pm by MartinMart »
 

Offline mon2

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Re: Read/Write EEPROM Fairchild NM93C46 with Buspirate
« Reply #3 on: May 30, 2023, 11:12:46 pm »
Yes, the results should be consistent.

Go back to your original wiring but try with a slower clock value. The max clock is 400khz but suggest to try with 10khz, etc.
 

Offline MartinMartTopic starter

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Re: Read/Write EEPROM Fairchild NM93C46 with Buspirate
« Reply #4 on: May 31, 2023, 05:26:23 pm »
Also did not change anything, tried all available khz (5, 50, 100), same result only 0xFF (which I also get if I have nothing connected to the buspirate at all)
I redid one solder and then checked all connections again with the multimeter, all looks fine. (used 200 Ohm)
When I swap DI/DO I get random values, so I am pretty sure my standard connections is right.
Already tried to initiate/close the command with ]/[ instead of [/] as well, didn't change anything either.

I also checked if the EEPROM still works in its original use and it does, so I did not kill it yet  8)

Any further things I could try? I am slowly running out of ideas...
 

Offline mon2

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Re: Read/Write EEPROM Fairchild NM93C46 with Buspirate
« Reply #5 on: May 31, 2023, 05:54:26 pm »
I would suggest that you power the EEprom @ 3v3.

Then follow this article and update this thread for future readers:

https://medium.com/@rxseger/spi-interfacing-experiments-eeproms-bus-pirate-adc-opt101-with-raspberry-pi-9c819511efea

PS: Personally do not own this buspirate tool but have written lots of bit-bang code from scratch to R/W/E microwire and SPI / QSPI devices.
 

Offline MartinMartTopic starter

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Re: Read/Write EEPROM Fairchild NM93C46 with Buspirate
« Reply #6 on: June 05, 2023, 07:13:41 pm »
Thanks for your help, in the end I just had to update the buspirate firmware... :D
 


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