Re-Programming EEprom Chip

Deleted member 115935

Joined Dec 31, 1969
0
Since we seem to be discussing an I2C interface as long as you can get the on board master to STFU any other device can claim the bus and control all devices there.

So there is hope after all.
Just a thought
not all the small processors systems I have seen with I2C, support multi master

so this may / may not work.

Also they need to check the prom itself, see if it has a write protection pin,
which might go directly to the processor.
 

Thread Starter

RichTea1973

Joined Sep 1, 2021
11
Just a thought
not all the small processors systems I have seen with I2C, support multi master

so this may / may not work.

Also they need to check the prom itself, see if it has a write protection pin,
which might go directly to the processor.
Hi All,

Am am just looking to change a digit the the manufacturer date, not to re-write the program written on it. From the sounds of things, I am in the wrong place to get a process together to achieve this, or perhaps its just not possible?
 

Sensacell

Joined Jun 19, 2012
2,917
Hi All,

Am am just looking to change a digit the the manufacturer date, not to re-write the program written on it. From the sounds of things, I am in the wrong place to get a process together to achieve this, or perhaps its just not possible?

What you suggest is "possible" - but extremely unlikely. (Bitcoin going to$100K next week is 1000X more probable)

How do you figure out WHICH BITS contain the date? how can you be sure there is no checksum byte? How do you know how to format the "new" date?
It could be coded in many different ways. (almost certainly NOT in a human-readable format)
The only way you could conceivably pull this off is with the help of the person that wrote the code- or by spending MONTHS doing investigations, trial, and error.
 

ErnieM

Joined Apr 24, 2011
8,196
Am am just looking to change a digit the the manufacturer date, not to re-write the program written on it. From the sounds of things, I am in the wrong place to get a process together to achieve this, or perhaps its just not possible?
*IF* the date is stored in that PCA9500 and you can read it out you only have 256 bytes to contend with, assuming they are all at some interesting value and not 00xH or FFxH (which gives you less bytes to inspect). Since it seems you already have a brick you can try a random change of each byte and see if anything helpful develops.

Sorry there are so many naysayers here , some of whome seem to have never worked the I2C protocol the expander/EEPROM uses.

Is there a second side of this board? I could not identify any controller chip from my look-see.
 

Papabravo

Joined Feb 24, 2006
17,288
I guess I would start by seeing if you can dump the contents of the PCA9500. As has been pointed out you only have 256 bytes to worry about. If the date is in plain text you'll be most of the way there.
 

Thread Starter

RichTea1973

Joined Sep 1, 2021
11
I guess I would start by seeing if you can dump the contents of the PCA9500. As has been pointed out you only have 256 bytes to worry about. If the date is in plain text you'll be most of the way there.
Thanks All,

So what I am thinking is to desolder the PCA9500 chip, and connect it to a Dataman40 pro (still to buy this, although recommendations appreciated), dump the chip, inspect to find the date, maybe I will maybe I won't. Make the change as required and write the contents back, assuming it not locked.

Is the process correct?

If it is locked, is it totally game over?

Is there a better/cheaper programmer to use which as the dataman device supports tons of chip, and may wish to use on other projects?

Many thanks

Rich
 

ericgibbs

Joined Jan 29, 2010
14,183
hi RT1973,
I don't see a real time clock on the PCB.?
So how does the MCU that reads the PCA9500 know that the memorised Date has been exceeded ???

E
 

Thread Starter

RichTea1973

Joined Sep 1, 2021
11
hi RT1973,
I don't see a real time clock on the PCB.?
So how does the MCU that reads the PCA9500 know that the memorised Date has been exceeded ???

E
At this stage, its all about changing the date, the comparator will be on the board this one attaches to.

Regards

Rich
 

ericgibbs

Joined Jan 29, 2010
14,183
hi Rich,
I don't see how the programmed Date in the PCA can effect the operation of the unit.

If you plan to Read and Reprogram the PCA, what will you change.?

Eric


Update:
Are you trying to build a working unit, using different type PCB cards.??
 

Thread Starter

RichTea1973

Joined Sep 1, 2021
11
hi Rich,
I don't see how the programmed Date in the PCA can effect the operation of the unit.

If you plan to Read and Reprogram the PCA, what will you change.?

Eric
Hi Eric,

Its all in the thread. Just looking for the process to be confirmed and suggested device to use.

Regards

Rich
 

ericgibbs

Joined Jan 29, 2010
14,183
hi Rich,
OK.
The pins of interest on the PCA9500, 15, 14, 13 ,, SDA, SCL /WC ,
Lift the pins of these 3 pins, off the PCB pads using a soldering iron and fine metal tipped tool.

Connect short wires to the pins, to be used to connect to say a Arduino SDA, SCL and I/O pins.

Connect the 0v pin #7 to the Arduino 0V.

Write a program for the Arduino to READ the PCA9500, show the read data on the IDE serial.

Power up the PCA9500 PCB.

Run the Arduino program.

E
20210901_152603.jpgESP_ 733 Sep. 04 10.01.png
 

Thread Starter

RichTea1973

Joined Sep 1, 2021
11
hi Rich,
OK.
The pins of interest on the PCA9500, 15, 14, 13 ,, SDA, SCL /WC ,
Lift the pins of these 3 pins, off the PCB pads using a soldering iron and fine metal tipped tool.

Connect short wires to the pins, to be used to connect to say a Arduino SDA, SCL and I/O pins.

Connect the 0v pin #7 to the Arduino 0V.

Write a program for the Arduino to READ the PCA9500, show the read data on the IDE serial.

Power up the PCA9500 PCB.

Run the Arduino program.

E
View attachment 247240View attachment 247241
Thankyou Eric,

You have certainly been the most helpful so far, is there a more intuitive device than the ardino as this is my first time trying to do this. The attraction of the dataman was the auto detect of the chip and the rather pleasant looking software that came with it. I suppose I am after some sort of middle ground between the ardino and the dataman.

Regards

Rich
 

ericgibbs

Joined Jan 29, 2010
14,183
hi Rich,
I can't think of any intermediate prommer.
You must have a mate up there who can knock up a quick Arduino Sketch.;)

I don't think the data in the EPROM will be a Date, more like a Batch or Issue number.

Has the project/PCB setup ever worked for you.?
E
 

ErnieM

Joined Apr 24, 2011
8,196
THE EPROM could also save a cycle count, how many recharge cycles have been done. If so, the number zero may be your friend.
 
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