Hacking cartridge HP 84/85

[MAsic12345]

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7.jpg (156.07 KiB) Viewed 23662 times

[dragonator]

Is the hole you pointed to in some way connected to the printer? I suspect the bellows exist to pressurize the ink (or maybe even to create a vacuum), but that would only be possible if that hole is connected to the printer in some way.

In any other way it is pretty similar inside to most other printheads I know. The bellows were the only odd thing I saw so far.

[MAsic12345]

the hole is not connected to the printer
printer creates ink pressure

I understood what this air bubble is for.
the bubble is a valve and it regulates the pressure in the print head
Constant pressure is applied to the print head.if there is not enough ink in the head tank a vacuum is formed
then into the bubble through the upper valve air is drawn and it swells up and opens the constant ink pressure valve

[MAsic12345]

Here came across an interesting little thing
when scanning I noticed that the signal that is fed to the head during the first pass of the carriage is clear and can be disassembled,
On another pass of the printhead carriage the signal is already strange and not intelligible
Maybe someone knows what it is connected with?

Here is a print of one image

First image - first pass of the printhead

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The second image is the second pass of the print head which prints the same image

2.png (38.12 KiB) Viewed 23483 times

Maybe someone knows what it is connected with?

[MAsic12345]

question for experts
How can I make simultaneous control of pins in teense and give a different signal on pins simultaneously?
or where can i read about this

[dragonator]

There are a few ways to do this on a Teensy.

The first, and simplest is to write a whole port:
https://www.pjrc.com/teensy/pins.html
https://forum.pjrc.com/threads/17532-Tu ... #post21228

This way you can set 8 pins at the same time. The command itself executes extremely fast (within a microsecond) so calling it quickly for 2 different ports should not be an issue. Just try to have the clock always be the last thing to call, so all the data will be processed by the cartridge.

Another, better but way more difficult way is with DMA, which is not sensitive to interrupts and other external problems. It still only calls one port at a time, but the delays between the 2 are even smaller (<500ns). I do have a program that uses DMA on a Teensy I can share, but it will not be that simple to use, so if the above is adequate, I would try that first.

[MAsic12345]

https://ru.stackoverflow.com/questions/ ... %B8-%D0%B8

[MAsic12345]

There are a few ways to do this on a Teensy.

But can this be done with timers on Teensy3.6?

[dragonator]

Teensy 3.6 has most of the same functions as a Teensy 3.2. However, I have only worked on DMA for 3.2, and have not yet made a universal library. Everything on the 3.6 is something that for now I cannot help with much.

I do now have time, and want to pick up HP84 myself as well, but expect it to be slow the first few weeks. I will see if I can analyze your waveform files and write them with the Teensy 3.2.

[MAsic12345]

Well, I'll throw off the latest data that I received

This program is my analyzer
will be needed to open the data that i'll send
http://www.qdkingst.com/en/download

here is the link to the archive
will open in PDF but if you download it will download ZIP
https://drive.google.com/open?id=1kx69K ... w1G5mkGVz5

plus I put together a 3.3 volt od tency power management circuit from teensy
this circuit allows you to turn on and off for a short time the power
supply of 5 volts, 9 volts and 12 volts while programming the microcontroller
you can ignore the left side of the circuit, it's just connectors