PicoCNC is now fully open source.

[phil-barrett]

2 Announcements.

I am retiring the PicoCNC controller board. Is is no longer for sale.

But more importantly, I have made the full PicoCNC design available as open source with the MIT License. This includes all KiCAD files, gerbers, BOM and Pick-n-Place files for contract manufacturing. The BOM includes LCSC/JLCPCB part numbers.

See here for more details

[papyDoctor]

Hi Phil,
I bought the RP23CNC from Tindie, just for my comprehension, is your board the same as RP23U5XBB ?
Thank you,
Olivier

[papyDoctor]

"FWD was a conscious omission as the relay driver chip only has 7 channels"
I don't understand, It's just a matter to add diodes at the same places as the R50-R57

[phil-barrett]

R50-R57?? There is no R50. R51 is a current limiter for the spindle enable LED. R52 is a pull-up for the wz850io Interrupt line. R52-R57 do not exist on the board. The only outputs capable of driving a relay coil (> 20 mA) are in the ULN2003 driver chip which is the 7 relay outputs on the board.

Perhaps you are looking a different schematic? The one I released is here.

[papyDoctor]

Sorry, I'm speaking about the RP23CNC here:
https://github.com/phil-barrett/RP23CNC/blob/main/Schematic/V1.0%20schematic.pdf

[phil-barrett]

Ah, you are talking about the RP23CNC, not the PicoCNC board.

Those are user supplied resistors used to pull up the open collector outputs of the ULN2003A. Note that the ULN2003A has kickback diodes built in. The PicoCNC has the same chip for driving relays. Here's the full schematic of a single channel:

But, to your point about Spindle Direction. It is sometimes used in lathes and lasers. For lasers, typically, you can use 5V logic so no relay driver is needed. And, nothing prevents one from using a 5V relay driver on the spindle direction output. So, that is why no relay driver for spindle direction is provided.

[papyDoctor]

Ah sorry, I missed this feature of the ULN2003, thank you.