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Grogster

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Posted: 01:26am 07 Oct 2015

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Just when I thought I had nailed my I2C EEPROM issues, I am having major issues trying to read and write to a 24LC32A.

This device uses word addressing as most EEPROM chips or FRAM does, but the code that does work fine on a FRAM chip, won't work on this device.

Is there something special about the 24LC32 which would make it incompatible with the I2C commands?

I am trying to talk to it on a MM+.

Test code:

A=1 'Address byte
B=1 '1st data byte
C=2 '2nd data byte
D=3 '3rd data byte
E=4 '4th data byte

I2C OPEN 100,100

I2C WRITE &B1010000,0,6,A\256,A Mod 256,B,C,D,E 'Write four bytes from address 1
Pause 10 'make sure EEPROM has time to write(5ms needed)

I2C WRITE &B1010000,0,2,A\256,A Mod 256 'Reset memory pointer to 1.
Pause 10
I2C READ &B1010000,0,4,D$ 'Read four bytes into D$
Print len(D$)
B1=asc(mid$(D$,1,1))
C1=asc(mid$(D$,2,1))
D1=asc(mid$(D$,3,1))
E1=asc(mid$(D$,4,1))
Print B1,C1,D1,E1

This code always returns with:

4
0 2 0 0

I am expecting and needing it to return with:

4
1 2 3 4

I can't see what the hell I am doing wrong, and my brain now hurts - especially as I thought I had nailed these feckin' EEPROM chips.

The only thing I can think of is that the 24LC32A is not a compatible device.....

YES - 4k7 pull-up's to 3v3, and datasheet says that device is happy with any voltage greater then-equal to 2.5v, which it has.

YES - Address pins are correct - pins 1-4 are all connected directly to ground.

Will ALWAYS only be four bytes, so figured I should be able to send them all in one command along with the address bytes - so 6 bytes in total. 'A\256' and 'A Mod 256' have been used before with great success on the FRAM chips - I don't see how the addressing is different, but maybe it is?

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

matherp
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Posted: 01:50am 07 Oct 2015

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Try

I2C WRITE &B1010000,1,2,A\256,A Mod 256 'Reset memory pointer to 1.

as the write before the read.

In general when reading after sending an address the write should use option 1 to avoid sending a stop code

UPDATE:

If you are using the 24C32 on a DS3231 board the default address is &B1010111

The following code is tested and works on a Micromite b32 with a DS3231 board

option explicit
option default integer
dim A=1 'Address byte
dim B=1 '1st data byte
dim C=2 '2nd data byte
dim D=3 '3rd data byte
dim E=4 '4th data byte
dim d6$
DIM B1,C1,D1,E1
I2C OPEN 100,0

I2C WRITE &B1010111,0,6,A\256,A Mod 256,B,C,D,E 'Write four bytes from address 1
Pause 10 'make sure EEPROM has time to write(5ms needed)

I2C WRITE &B1010111,1,2,A\256,A Mod 256 'Reset memory pointer to 1.
I2C READ &B1010111,0,4,D6$ 'Read four bytes into D$
Print len(D6$)
B1=asc(mid$(D6$,1,1))
C1=asc(mid$(D6$,2,1))
D1=asc(mid$(D6$,3,1))
E1=asc(mid$(D6$,4,1))
Print B1,C1,D1,E1

Edited by matherp 2015-10-08

viscomjim
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Posted: 09:20am 07 Oct 2015

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Thats interesting, I have never used the 1 before, I will have to give that a try.

Grogster

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Posted: 10:35am 07 Oct 2015

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Hi - thanks guys.
I'm away for a day job, but will try this out later.

In other eeprom I have used, you reset the address pointer by specifically sending the address bytes followed by a stop. That way, the pointer gets moved, but no data is exchanged.

Odd....

I will let you know what happens later tonight(my time).

EEPROM is a Microchip 24LC32A SOIC on my own PCB.
It is not on a RTC module or other pre-assembled module from eBay.

WP(pin7) is grounded, so writing should be possible.

I'll post back tonight - stay tuned!

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

jman

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Posted: 04:08pm 07 Oct 2015

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Hi G

add this after the write

Print "0=ok 1=nack 2=timeout"; mm.i2c

If you get a 0 then the write was good this way no guess work

Regards
Jman

Grogster

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Posted: 05:42pm 07 Oct 2015

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RESULTS:

4
0 0 0 0

? mm.i2c results in 2 - timeout.

Code changed to reflect the 000 address pins I have.

Screenshots:

EDIT: Here is a shot of how I have the EEPROM connected to the MM+:

Next thing is to pull out the logic analyzer and see if we are getting things happening on the I2C pins - will post results of this test soon.

EDIT: Cannot run logic analyzer. Keep getting "I2C is busy" error messages. Even with pause 500's between writes or read attempts.

Is it possible there is a bug with the MM+ I2C?

I will now try the same code on a 170 and see what happens.

EDIT: Have got rid of the "I2C is busy" error - removed the logic analyzer - it's wires must have been holding the bus till you start sampling. Will start running then connect analyzer.
Edited by Grogster 2015-10-09

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jman

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Posted: 07:22pm 07 Oct 2015

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Hi G

Try this

I2C open 100,100

For I = 8 To &H77
I2C Read I, 1, 1, A
If MM.I2C = 0 Then GoTo Found
Pause 5
Next I

Print "No I2C device found"

End

Found:
Print "Address is ";"&H";Hex$(I)

Post the results

Jman

Grogster

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Posted: 08:50pm 07 Oct 2015

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RESULTS:

Results from the logic analyser:

EDIT: Analyser results are from my previous attempts, not jman's test code.
I have yet to try any of this code on a 170, but that is next. I will cut the SCL and SDA tracks to the MM+ chip, and hop onto these from a 170.Edited by Grogster 2015-10-09

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matherp
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Posted: 08:50pm 07 Oct 2015

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Grogs

Is WP tied low? This has to be connected and must be low to allow writes.
A0,A1, A2, VSS are all obviously connected but do they also connect to GND? Difficult to tell from the pic.

Do you still design boards without a schematic? It really really makes things easier if you start from the schematic and then the design check in the PCB software can make sure the layout is correct.

Grogster

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Posted: 08:56pm 07 Oct 2015

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@ matherp - yes WP grounded - see post #4.

According to the test-tool in the layout software, all points that should be ground, are ground:

I do have a couple of those RTC/EEPROM eBay modules, so I might hook one of them up to a spare MM+ and see if I have the same issue.

EDIT: I don't know why it did not occur to me to check this earlier, but I am running 4.7 Beta 23 on this module - I will upgrade to the latest - this may well be something that has been fixed - worth a try.Edited by Grogster 2015-10-09

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TassyJim

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Posted: 09:00pm 07 Oct 2015

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I didn't have a 24LC32 but I do have a 24LC256.
On a MM+ explore64 this works OK.

LIST ALL
' TassyJim
'
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Option explicit
Option default integer
Dim A=1 'Address byte
Dim B=1 '1st data byte
Dim C=2 '2nd data byte
Dim D=3 '3rd data byte
Dim E=4 '4th data byte
Dim d6$
Dim B1,C1,D1,E1
I2C OPEN 100,0

I2C WRITE &B1010000,0,6,A\256,A Mod 256,B,C,D,E 'Write four bytes from address 1
Pause 10 'make sure EEPROM has time to write(5ms needed)
Print MM.I2C

I2C WRITE &B1010000,1,2,A\256,A Mod 256 'Reset memory pointer to 1.
I2C READ &B1010000,0,4,D6$ 'Read four bytes into D$
Print Len(D6$)
B1=Asc(Mid$(D6$,1,1))
C1=Asc(Mid$(D6$,2,1))
D1=Asc(Mid$(D6$,3,1))
E1=Asc(Mid$(D6$,4,1))
Print B1,C1,D1,E1

> RUN
0
4
1 2 3 4
>

What pins are you using?
I use I2C (1) pins 43 and 44.

Jim

Edit: I just traced your board. The pins look correct so I think the beta32 will fix it.
Edited by TassyJim 2015-10-09

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Grogster

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Posted: 09:05pm 07 Oct 2015

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Yes, pins 43 and 44 - see images above.
This is what I can't understand - it should be working, but isn't - I hate these sorts of feckin' issues.

I will check for continuity on the SCL and SDA tracks - perhaps we have a fluffy via on the PCB or something. I will also check that ALL pins 1-4 and 7 are indeed grounded.

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jman

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Posted: 09:14pm 07 Oct 2015

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Grogster said RESULTS:

This indicates a hardware error of some sort
PCB the I2C device itself..

Jman

Grogster

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Posted: 09:15pm 07 Oct 2015

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EXCREMENT!

...I have a working theory - stay tuned for an update...(board is slightly different to the version in the images - no feckin' pull-ups on SDA or SCL at all, despite what I insisted was the case in post #1.

...please don't kill me, if this ends up being the problem, and it probably is, as those pull-ups are essential........

Will fit some now, and get back ASAFP.

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

matherp
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Posted: 09:24pm 07 Oct 2015

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Grogs

After opening "I2C OPEN 100,100" insert the command

poke &HBF886358,&H600

This should (may) enable the chips internal pullups on the i2C lines

Grogster

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Posted: 09:35pm 07 Oct 2015

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Thanks for the poke, but I have added 4k7's now, and am getting a response to jman's code.

I am trying to run my original code now, but the MM+ is complaining about my use of variable D when D$ has been defined.

Once OPTION EXPLICIT has been issued, is there any way to disable it?
Nothing wants to work. Have cycled power, NEW'd the program, xmodem'd another copy across without the option explicit, but it keeps telling me about it. Reset etc, won't go away. Will try hard-reset.

One step away from proving a point with my mistake, but can't get away from the explicit problem now. I could just change the code to make a point, but I want to get rid of that now that it won't let me turn it off.

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

matherp
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Posted: 09:37pm 07 Oct 2015

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Quote variable D when D$ has been defined.

None of the latest versions of the Micromite firmware allow this (since 4.7 I think)- nothing to do with options. I corrected it in my version of your code.Edited by matherp 2015-10-09

Grogster

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Posted: 09:41pm 07 Oct 2015

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Hard-reset does not clear that option explicit once defined. Would love to be able to disable it.....

For now, I just changed the code, and guess what? (rhetorical)

And with my ORIGINAL feckin' code:

Schoolboy mistake, and I should have known better.....

My sincerest apologies for wasting everyone's time - sheesh......

EDIT: ....and the analyser output looks much healtier too now....

CURSES!!!!!!!!

Edited by Grogster 2015-10-09

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TassyJim

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Posted: 10:43pm 07 Oct 2015

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Grogster said
Once OPTION EXPLICIT has been issued, is there any way to disable it?

From the manual:
OPTION EXPLICIT
Placing this command at the start of a program will require that every variable be explicitly declared using the DIM command before it can be used in the program.
This option is disabled by default when a program is run. If it is used it must be specified before any variables are used.

Good to see it working at last.
Jim

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Geoffg

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Posted: 03:32am 08 Oct 2015

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I love this, it is better than watching high drama on the TV.

Geoff Graham - http://geoffg.net

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