New
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PiBot V3.28 Isolated
ATmega328P · GRBL 1.1h · Full Optocoupler Isolation
Isolated for Real Machines
XXYYZ
5 Outputs
GRBL 1.1h
Firmware
100%
Isolated I/O
0–10V
Spindle Output
True Isolation
B0505S DC-DC isolated power + optocouplers
High-Speed PWM
Toshiba TLP2395 optocoupler
0–10V Output
Direct VFD speed control
XXYYZ Dual
X & Y each 2 outputs
Full LED Status
Every I/O pin has LED indicator
Onboard + External
Both driver types supported
24V / 12V Input
Industrial switch compatible
Reverse Protection
Anti-reverse polarity design
V3.28 Isolated vs. Arduino CNC Shield
The Arduino CNC Shield is common — but it has zero isolation, no 0–10V, and no reverse protection.
Two Firmware Options
Flash either version from your browser — PiBot WebSerial Tool — plug USB, click flash, done.
Note: Custom firmware is optimized for V3.28 Isolated hardware. To build it yourself, edit
All outputs active-high. Active-low inputs: X/Y/Z limits, probe, abort, resume, hold. Short signal to GND with a jumper to test.
CH340 Driver: If serial port not listed, install CH340/CH341 driver first.
config.h.All outputs active-high. Active-low inputs: X/Y/Z limits, probe, abort, resume, hold. Short signal to GND with a jumper to test.
CH340 Driver: If serial port not listed, install CH340/CH341 driver first.
Get Started
1
Plug in USB
Connect V3.28 to PC. Install CH340 driver if needed (Windows).
2
Wire drivers
Use onboard driver sockets or connect external drivers (TB6600, DM542, etc.) via Step/Dir/Enable.
3
Open sender
Candle, UGS, LightBurn, bCNC — any GRBL sender. Baud: 115200.
4
Configure
Type
$$ to view settings. Set steps/mm, speed, acceleration for your machine.Board Pinout
1
Limits & Probe Inputs
X / Y / Z Limit + Probe · each GND & SW-VCC
2
Button Inputs
ABORT, HOLD, RESUM, REST · each GND
3
Isolated Outputs
GND-ISO, ISO-COOLMIST (A4), ISO-COOLANT (A3), ISO-DIR-EN (D13)
4
Isolated PWM Output
GND-ISO, ISO-PWM (D11)
5
Analog Output (PWM Sync)
GND, 0~10V
6
Main Power 12~24V
GND, VIN
7
Driver Motor Power
GND, Vmot-Driver
8
Onboard Driver Jumpers
MS1 / MS2 / MS3 · 1 = Logic High, 0 = Logic Low
9
External Driver Signals
EN / STP / DIR / GND to Driver X1, X2, Y1, Y2, Z
10
Onboard Driver to Motors
2B / 2A / 1A / 1B to Motor X1, X2, Y1, Y2, Z
11
USB-C
USB connection to PC
12
RST Button
Hardware reset
13
SW-VCC Voltage Selection
5V (jumper left, default) OR Vmot-Main (jumper right)
14
ICSP
MISO / 5V, SCK / MOSI, RST / GND
15
IO Header
A4 / 5V, A6 / 5V, A7 / GND
Specifications
PiBot Electronics · pibot.com · Shipping worldwide since 2013
© PiBot Electronics · pibot.com
© PiBot Electronics · pibot.com
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