Using a voltage leveler and external drivers is something that came up before. Here's a servo driver hacked and tested before installing in a retrofit.

https://plus.google.com/109943375272933711160/posts/gJqGm3VRKDZ

Relief from bitmap, 2"x1.5", 1/32" carver bit.

Just tried a Rpi2 plugged into the TinyG over my network but it's not quite working. I connected to the Rpi IP address from my laptop and it saw the thing, connected (picture came up and one without a picture?) but sorta stalled never getting to ready. Oddly, some things would work like reset but no jog, jogging worked fine on the Rpi running chilipeppr (no webgl support :-().

Just wondered if anybody else had this flaky connection before I dig in more. Almost... next is the video widget. A client runs his 3d printer over the web so I wanted to show him Chilipeppr could do the same thing.

Some photos of using TinyG 3.3v step, dir and enable external driver outputs to a 3 phase 5v servo driver.
The servo has a brake on it that needs 24vdc so I wired a relay from the servos 5v output to trip a wall wart to power it whenever the driver is on, which releases it. Power off and the brake sets preventing the spindle from crashing into the work or table. I'll post pictures of Chilipeppr running the machine after I get the control box wired up now that I know it all works.

Just trying the GPIO widget to connect to the rPi3 / TinyG from my laptop and ran into a no permissions error setting pins and busy if I tried the pin again. I have never done any GPIO on Rpi, only Arduino, so forgive my ignorance.
Is there anybody using this yet? I could really use it. The other wifi stuff via SPJS seems to work well so far running jobs. I can easily flip the coolant and spindle with relays I wired up to the TinyG but I also have a 12vdc break I need to flip flop with the z axis motor power to prevent the spindle crashing through some very expensive glass. I have not hooked up the PWM for the spindle yet and we have some other things we want to control later. If it all works our R&D conversion will show how this is not just a hobby tool and give Chilipeppr/TinyG some real world industrial machine legitimacy for education.