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Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 06:12am 16 Dec 2022

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Trying to make a 24FC01 EEPROM co-operate with a PicoMite.

PicoMite seems to know it is there, cos the test code on this thread produces the following result:

So, the PM is getting ACK's from addresses &h50 to &h57, which is correct, as this EEPROM does not use the address pins/bits, and so does not care what you set them to or if they are floating even - it will respond on any of those addresses, and that is proven with the little test program.

So, that's good.

But I cannot get any kind of data into or out of the damn thing, even though the MM.I2C variable is reporting everything is good.

My test code is:

SetPin GP6,GP7,I2C2
I2C2 Open 100,100

Dim D$,E$

D$=Str$(&h00)+"1234567" 'Address of zero + the data bytes; 8-byte page
I2C2 Write &h50,0,8,D$
Pause 10 'Allow time for EEPROM to do its page-write thing...(at least 5ms)
Print MM.I2C
Print "Attempting readback..."
Pause 1000
I2C2 Write &h50,0,1,&h00 'Reset the byte address pointer thing
Pause 10
I2C2 Read &h50,0,7,E$
Print MM.I2C
Print E$

The result I get is:

So, no NACK's, but the data does not come back 1234567 as expected.

Can anyone see what I am doing wrong?
I can hook up the logic analyzer if I have to, but perhaps someone can see what I am doing wrong without having to get that deep into things.

24FC01 has an 8-byte page-write ability, so I should be able to write 7 ASCII bytes, combined with the memory pointer byte to make our 8-byte page. I stop then, and MMBASIC should send the stop for me, and the EEPROM should then do the page write.
MM.I2C seems to suggest this is all good, but I don't get the data back that I have tried to write.

EEPROM powered from 3v3 Waveshare Zero module 3v3 output, 100n cap across the EEPROM, 4k7 pullups to SCL and SDA on that same 3v3 supply.

I would love some pointers on what I should/could try next at this point.

Smoke makes things work. When the smoke gets out, it stops!

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 06:33am 16 Dec 2022

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Write protect not set right?

VK7JH
MMedit

Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 06:35am 16 Dec 2022

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IGNORE....Fixed it...

Smoke makes things work. When the smoke gets out, it stops!

Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 06:40am 16 Dec 2022

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Write protect set correctly (pulled directly to GND)

I had made a mistake using STR$(&h00) for my EEPROM index reference byte for the pointer thing. �

STR$(&h00) produces a zero, which is ASCII 48, which is &h30, so the EEPROM was writing at &h30, but I was trying to read it back from &h00....

Damn, computers are pedantic, aren't they?! (rhetorical)

Changed the line to: D$=Chr$(&h00)+"1234567"

That correctly makes byte 1 of the string decimal zero rather then decimal 48 disguised as a zero when printed on the screen!

Time for a break, but I can come back and tinker around a bit more now that I have found my mistake!
Edited 2022-12-16 16:41 by Grogster

Smoke makes things work. When the smoke gets out, it stops!

Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9610

Posted: 08:25am 16 Dec 2022

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UPDATE: Here is a result of outputting all 128 bytes from the EEPROM:

Note that there is a "1234567" towards the right of the first line - this will be where I was accidentally writing to the wrong address. So it was working, I just didn't know it was.

Onwards...

Smoke makes things work. When the smoke gets out, it stops!

twofingers