Cracking the 1290 chip
Before emailing me please read this.

Part1 cracking the 2100p protocol

My Home brew CIS

26th Jan 2003.
Since posting my 2100p chip hack and my chip resetting program I have had quite a few inquiries from large format epson owners seeking resetters. The desktop printer owners are pretty well catered for with reasonably priced universal resetters. Some people still complain about the price but really they can pay for themselves after one cartridge set is refilled. The professionals are not so lucky. One of my contacts informed me that the 7600 can use chips out of the 870/1270/1290 etc series desktops. The pin out is obviously different so the printer must have be modified. Anyway I though it might be worth cracking the 1290 and if possible adding this series to my reseter. I don't have any of these printers so I bought a commercial reseter to see what the signals look like. If I can do the 1290 I may be able to do the 7600 etc.

This is what a commercial chip reseter sends to the chip. The traces are (from top) pads 1,5,6,7 and 4.

My best (but probably wrong) theory is :-
5 is obviously a clock for synchronous serial.
6 is power (this is known from data sent to me about fake chips)
4 is a select line which is high for black chips and low for color one.
That leaves 1 and 7.

A least one of them will be a data line and the other could be a read/write.
If the ink level is stored the same way as the 2100p style chips then 1 is data and 7 is R/W and write = high.

Alternatively the R/W may be encoded in the serial data as it is in the 2100p. But you don't need the other line then.

I can't talk to the chip at all. I may have killed it somehow. The ILRS seem to output 4.6V so I would expect the chips to work on the 5V supply I'm using but maybe not.

Time to dust off the CRO I guess.

27th Jan 2003.
I managed to read and write the chip with a micro. I was close. Pad 4 is the R/W and pad 7 appears to a reset/sync line. I erased most of the data in the chips while I was working it out but they appear to have about 32 bytes of data in them like the 2100p. The next step is to make an adapter so I can access them directly from the PC.

2 hours later.
It works. Not much more to say here. The program is over at this page.

My home page.