Spark Logic

Geeetech GTM32 connection guide

Geeetech GTM32 Geeetech GTM32 wiring guide with power, signal assignments, and bench checks.

Geeetech GTM32

78 contacts Current package

Geeetech · STM32F103VET6 · Separate main and bed 12 V branches.

Power only the main electronics

Required

Disconnect heaters, fans, motors and the bed expansion board. With the bench supply off, match the P3 mating housing and verify continuity of its ground contacts. Use a current-limited 12 V DC bench supply on the main branch.

Bench 12 V feeds P3-2 and its return connects to the P3 ground contacts. The bed supply is open.Bench supplyP3 header+12 VP3-2 VDCReturnP3-1/4 GND

Bench checks

  • Leave P3-3 open. Verify polarity against the manufacturer diagram before enabling power.
  • Verify the regulated 3.3 V endstop supply against ground before connecting the host.

Geeetech GTM32 Board · manufacturer connector circuit drawing · P3 and endstop circuits

Connection scenarios

Identify the USB serial interface

With the controller in the logic-only fixture, attach a standard USB Type-B data cable to a computer.

Bench checks

  • Confirm that the USB serial device enumerates. Select the baud rate from the printer firmware documentation.
  • Read the firmware identification with motors and heaters disconnected.

Geeetech GTM32 Board · Interface and USB serial setup

Geeetech GTM32 wiring map

Highlighted contacts are used in the required step or selected circuit. Select a contact to inspect it.

P3 fused 12 V inputs
Contact numbers follow the circuit drawing.
HB bed expansion header
Contact numbers follow the circuit drawing.
EXT0 extruder header
Contact numbers follow the circuit drawing.
Endstop header
Contact numbers follow the circuit drawing.
P2 motor header
Contact numbers follow the circuit drawing.
FAN0 board fan
Contact numbers follow the circuit drawing.
SD card ribbon
10-position FFC contact order. Shell anchors 11 and 12 go to ground.
LCD ribbon
12-position FFC contact order. Shell anchors 13 and 14 go to ground.
USB Type-B
USB Type-B contact numbering.
Selected pin details

SD-4 · GND

Return · Ground

Connect to the board ground return.

Geeetech GTM32 Board · manufacturer connector circuit drawing

Electrical limits · Pin in the reference

Models and documents

Contact numbers follow the original Geeetech circuit drawing. The separate harness illustrations use their own numbering and view. The map covers P3, HB, EXT0, endstops, P2, FAN0, SD, LCD and USB. Confirm any Wi-Fi or other auxiliary connector in its own documentation.

Geeetech GTM32
STM32F103VET6 · Separate main and bed 12 V branches.