I did some more testing.
It seems the stupid printer really notices if the value in the chips is
different from the value in it's own memory.
Because i noticed the writing is only done when the power is removed. So i
simply pulled the chips before switching off. But at next power up the
printer did a cleaning cycle.
I'm still not sure how the chips work. The readout is clear, there are 4
transmissions, i think one for each chip. It's always clock and data, very
normal. But for writing there seems also to be some fast clock, and then
some slow clock. Any idea what is transmitted there? It is only a single
block fast, then slow, not 4 blocks fast/slow fast/slow fast/slow
fast/slow as i would have expected. How does it write to the 4 chips then?
There is a small EPROM in the C84. I believe this must be the place where
it hides away the copy of the values the chips should have. I wonder if
one were able to disable writing to this the printer would not notice the
constant chip value. But that doesn't seem easy either since this is a
serial eprom and one can not simply interrupt the write enable wire.
So how is this going to work? Make a software for the micro that fakes the
chip, including the writing, and each time it is empty automatically reset
it to full? doesn't this waste ink?
My PC just reset itself for no apparent reason at all. I hope it's not
developing something, i do not need that right now ;-)
I will look into the eprom issue, ideall i would like to keep the value
constant everywhere forever with the printer being none the wiser.
ST
On Sat, 01 Jul 2006 00:58:16 +0200, Volkan Sahin <
vsahin@...>
wrote:
> If it is 15us then you don't need to worry about. You are right writing
> is much slower. You don't need a logic analyzer. Just built a micro
> connected to clk, data, resetb lines and start storing data after rising
> edge of reset signal, sampling should be done positive edge of the clk.
> Their format is indeed so easy first 4 bit hold address and write bit
> (MSB) and the 32 bytes of data comes.
> In T60x series cartridges first 2 bytes hold ink counter 3rd byte holds
> cartridge replacement counter, that's what I am calling, and 4th byte
> holds specific to printer ID. In empty cartridge first 4 bytes are
> always zero and after recharging they're initialized. Before start of
> every printing, printer checks all of the 4 bytes if they're different
> than the ones in battery backuped internal counters, it initiates
> recharging cycle.
> Don't forget that I have only experience with my CX4200 and these are
> my observations.
> Volkan