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FPGA + AVR for pen control?

Posted: Fri Sep 04, 2015 4:13 pm
by ezrec
Plan C (or whatever it's going to be called) will need to control far more pens.

Recently ran across this Spartan FPGA + AVR combo on

Spartan 6 XC6SLX9 FPGA with 84 digital ios (3.3v or 1.2v), and an Atmega32U4 with 8 analog ins.

The Atmega32U4 is used for programming the FPGA via USB - no JTAG device needed.

With a bit of software work, the Atmega32U4 could be a 'front end' for the Spartan 6, and you could send compressed print bands to the Spartan 6 (USB/SPI/Serial to the ATmega, which decompresses them and transfers them to the Spartan 6's internal 512K of RAM as needed).

Then the Atmega32U4 could start a DC Motor + Encoder, and the Spartan 6 could drive the pen jets as the ink axis moves along. As the Spartan empties it's 512K pen FIFO, the Atmega32U4 can feed additional pen control into the pen fifo, so that the 512K is not a limiting factor for total line resolution.

Re: FPGA + AVR for pen control?

Posted: Sat Sep 05, 2015 12:26 pm
by dragonator
Oasis is the current name of the printer. I don't like to have a progressive name plus I already skipped Plan A.

To be honest, I quite like this idea. You only need enough memory for one full sweep. I like to use steppers, but for inkjet I realize that at some point you cannot get the resolution out of them anymore. Have the spartan / 32U4 combo take care of the printing gantry and printhead, and let something lighter take care of all the other stuff.

Code and electronics is not really my specialty, so I cannot judge how well this will be a solution, but judging from what I know, it should work. I will look into it more to see what I can learn. It also gives me more reason to start hacking on the HP45 I have here.

Re: FPGA + AVR for pen control?

Posted: Tue Sep 08, 2015 9:14 pm
by ezrec
I believe BrundleFab's pen controller is a good demonstrator for the 'encoder driven inking' concept.

When you get to the point where you are interested in this, I have experience with VHDL and Verilog, and could code up something for you.

I'm getting started with a cheap Chinese delta FFM now (taking a break from melting sugar), but in a few weeks I should probably be ready for a new project to improve BrundleFab's inking speed.