Some may have heard of the products from:https://www.poscope.com/pokeys-devices
This little board (Pokeys 56U or 57U) can help us use a CNC router by connecting it to the PC through an USB port as opposed to the old way of using an LPT port (which is no longer supported on x64 versions of Windows).
They provide a plugin to be used with MACH3 software but also for the new version MACH4. It can be used on Windows up to and including Windows 10 (x32 and x64).
The board can be used for other things but this post is about using it with an CNC router.
The idea of making this project came to me after I saw that using the LPT port connection between PC and the motor drivers, the CNC router movements were quieter than using it with the PoKeys 56U board that I own together with the THB6064AH x3 motor driver board.
I saw that the PoKeys signals for the STEP were just a square signal with 50% duty cycle so the duration of the pulse was variable and depending of the frequency (the set speed in the MACH3 software). What I have done is to create a way of sensing when a transition from LOW to HIGH appear on the STEP signal and then create a signal with a certain duration.
I also added an charge pump signal detection (made with a PIC controller) that can trigger the STOP.
The DIP switches are used to change between a few presets for the pulse duration for each motor axis. Changing the pulse duration doesn't give great improvements so you can choose a combination and leave it like that. Important thing is to use it the same for all 3 channels.
Attached is an archive that contain:
- firmware for the ATTINY2313 master and slave (the MASTER is the ATTINY2313 that outputs the clock for the second ATTINY2313 which is labeled as SLAVE). By using the same clock I made sure that there are no differences in phase of the pulses for the motors. Those are made in Arduino IDE.
- firmware for the charge pump made with the PIC controller made in mikroC for PIC.
- EAGLE design files
- manufacturing files (GERBER files, GCODE for drilling holes, PDF files for the transparent film)
A picture of how the board will look:
And the schematics for those who don't want to look in the archive: