TL866 I2C programming problem - dodgy adaptor PCB

[Ash]

Hi,

So a while ago I bought a TL866 and it came with a bunch of PCB adaptors to allow it to program non-DIP chips. I've used it a few times to backup EPROMs from old test gear (why I bought it in the first place) and I've had no problems, its been good.

However today I needed to use it to program some SOIC8 I2C EEPROMs mounted on a PCB - cool I'll just use the dedicated cable and clip that came with it.

Well.. so I thought. It always read zeros, and if I tried to program it, verification would fail on the first byte. bugger...

So after a lot of messing around, involving pulling a chip off the board in case it was something there, I hooked up the scope and what do you know.. yep SDA line is ground.. hum.. buzzed out the connections and there was a short on the board between Ground (IC pin 4) and SDA (IC pin 5). 

So I fixed that and all was good!

This looks like it could be common as the ground track is very close to the pad.

So if you have one of these, do yourself a favour and just check for a short before you try to use it.   

Ash.

[vze1lryy]

I love my TL866 but I have never gotten a good read or write using that clip and cable. Not once. I have tried several of them. I always wind up soldering the chip to the adapter PCB and putting it into the TL866. I haven't ever had a short like that though. Jeez.

[Ash]

I love my TL866 but I have never gotten a good read or write using that clip and cable. Not once. I have tried several of them. I always wind up soldering the chip to the adapter PCB and putting it into the TL866. I haven't ever had a short like that though. Jeez.

I like the TL866 as well, but the ZIF socket is pretty cheap. But for the price of the unit, its awesome.

The clip seemed to work ok for me, but you have to be careful to get it aligned properly. Also if the chip is on a board, make sure the I2C address lines and Write protect are not being tied directly to gnd/vcc (its pretty common for them to be directly wired). The circuit I used had 10K pullup/down resistors on all these pins and the TL866 was able to drive them properly.

It would be cool to have the ability to configure the address to use for the I2C bus communications for an IC in the MiniPro application to get around this..

[edit]

Actually, thinking about it, if the TL866 has to "power" the rest of the circuit though the VCC pins on the EEPROM its not going to get very far. I was luck in that the EEPROM was isolated from the rest of the circuit (its on a plugin card and is used by the host to identify the card).

Ash.

[ralphrmartin]

Mine came with a load of little spring loaded sockets to put soic 8 chips and the like into. Good for programming the chips before you solder them in.