In-circuit eeprom programming

[RethoricalCheese]

Since not desoldering the eeprom chip takes much less time, I was thinking about in-circuit programming. I have CH341A programmer, which works perfectly and I got myself a SOIC8 test clip. Paired those two and connected it to a HP Pavilion 15 eeprom.

The problem is, that when I try to read from the chip, it only reads atleast 7 and up to 256 characters. No more, no less.

Any idea what causes this problem and how can I fix it?

[hansie55]

Re: In-circuit eeprom programming

I bought this test clip with the CH341a and it works ok.
You have to pay attention to the connection on the CH341a, that is not the same as the program says, but as on the pcb from the programmer.
Also, the clip on the chip has to be very good placed, makes also a difference.

http://www.ebay.nl/itm/381028670542?...%3AMEBIDX%3AIT

[RethoricalCheese]

Re: In-circuit eeprom programming

Had the same clip but without the wiring. That I made myself so it is made correctly.

And, it was placed very well because it read the first characters correctly. Problem was, it just did not read all of the characters. So maybe it works with some motherboards and doesn't work with others?

[stj]

Re: In-circuit eeprom programming

you cant read a chip in circuit for 2 reasons.
1: it's already hooked up to other chips that are putting voltage on it's data pins.
2: it may be in parallel with other serial devices like temperature sensors.

there is ONE possible way around this - on a working system.
boot into the bios and leave the menu on the screen while your reading the chip.
that will keep the cpu busy doing - not a lot.

[sparker1]

Re: In-circuit eeprom programming

I have the EZP2010 and always de-soldered the bios chip to re-program it but I read on another thread that you could do this in circuit with attachment clips. I ordered one and the results have been disappointing. I have never been able to get a chip to register with the programmer when using it with the clips in circuit and I guess stj has given the reason. But isn't this what the clips were made for?

[TossDon]

Re: In-circuit eeprom programming

I have TL866 programmer, it came with a adapter that has a interface chip on it, it looks cheap but works good, I also have the similar SOIC8 plain regular adapter without the interface chip, never was able to read completely using it. I think CH314 and TL866 are more the same but for the form factor, check their site to make sure you are using the right connector.

[hansie55]

Re: In-circuit eeprom programming

[QUOTE=stj;609586]you cant read a chip in circuit for 2 reasons.
1: it's already hooked up to other chips that are putting voltage on it's data pins.
2: it may be in parallel with other serial devices like temperature sensors.

In circuit does not necessarily mean with power on, so system off and there is no voltage on no pin.
I put the ch341a in usb with 5V supply and it reads the entire 8mb.

[RethoricalCheese]

Re: In-circuit eeprom programming

Indeed. I know it is possible (with power off). Just wondering why mine acted out.

But since it takes a lot of time to get a good connection using the clip, I would say desoldering method is faster Or I'm just very bad with the clip.

[R_J]

Re: In-circuit eeprom programming

The usb +5 volt supply can't power the circuit you are connecting to, there are other conponents connected to the vcc of the eeprom, like the microprocessor and its memory etc. even with the units power being off

[RethoricalCheese]

Re: In-circuit eeprom programming

An update to this topic.

A year has passed and I tried it again on some more laptops. Now it seems to work perfectly. Maybe it depended on the laptop design or something.

And also, I am trying to build a tiny pogo pin SPI adapter which might be much easier to operate.