GBB15

A gantry-mounted CAN stepper driver board for 15mm aluminum beams (mostly for PrintersForAnts printers).

This board can be used e.g. for the Micron to have A/B motor controllers directly at the gantry. This reduces the number of wires required to be routed to the gantry.

Additionally, this board can be used for Voron-0 or Tridents as a USB to CAN converter (using the Klipper CAN bridge option) with included A/B motor controllers.

JLCPCB Specifications

0. Upload GERBER-GBB15.zip
1. Select Qty
2. PCB Thickness 1.6mm
3. LeadFree HASL
4. Enable PCB Assembly
5. Choose Economic
6. Select Assembly Side Bottom Side
7. Tooling holes: Added by Customer
8. Press Confirm
9. Upload BOM-GBB15.csvand CPL-GBB15.csv
10. Check that all parts are in stock and click NEXT
11. Look for odd placement in the preview, select NEXT

Additionally needed LCSC parts

You can order these on LCSC

Part	Quantity	Notes	LCSC Part Number	Link
100u/35V/105°C capacitor	2		C3035369	https://www.lcsc.com/product-detail/Aluminum-Electrolytic-Capacitors-Leaded_Rubycon-35YXJ100MFFCT1-6-3X11_C3035369.html
MicroFit 3.0 connector	2	Tin or Gold	C277721 or C563821	https://www.lcsc.com/product-detail/Wire-To-Board-Wire-To-Wire-Connector_MOLEX-430450412_C277721.html or https://www.lcsc.com/product-detail/Pre-ordered-Connectors_MOLEX-430450413_C563821.html
JST PH 2.0mm 2-Pin conn.	4	Endstop/Thermistors	C131337	https://www.lcsc.com/product-detail/Wire-To-Board-Wire-To-Wire-Connector_JST-Sales-America-B2B-PH-K-S-LF-SN_C131337.html
JST XH 2.5mm 4-Pin conn.	2	Steppers	C144395	https://www.lcsc.com/product-detail/Wire-To-Board-Wire-To-Wire-Connector_JST-Sales-America-B4B-XH-A-LF-SN_C144395.html
Vertical THT USB-C conn.	1		C3151747	https://www.lcsc.com/product-detail/USB-Connectors_SHOU-HAN-TYPE-C-16PLC-H10-0_C3151747.html
CAN termination resistor	1	Optional!	C17909	https://www.lcsc.com/product-detail/Chip-Resistor-Surface-Mount_UNI-ROYAL-Uniroyal-Elec-1206W4F1200T5E_C17909.html
Tactile Switches	2	Boot/Reset	C255802	https://www.lcsc.com/product-detail/Tactile-Switches_HYP-Hongyuan-Precision-1TS002E-2500-2501-CT_C255802.html
Heat Sink	2	Standard TMC2209 heatsink	C5250902 or C5250879	https://www.lcsc.com/product-detail/Heat-sink-heatsink_wenhaoyongshun-D11-01-02_C5250902.html or https://www.lcsc.com/product-detail/Heat-sink-heatsink_wenhaoyongshun-F12-04-05_C5250879.html
1.5mm M.2 Thermal pad	1	Cut to size 67x15mm	--	https://www.amazon.de/-/en/Assorted-Thickness-Conductive-Silicone-Conductivity/dp/B07X38254H (DE) or https://www.amazon.com/ADWITS-12-Pack-Conductive-Silicone-Conductivity/dp/B07X81PRK7 (US)

Quick Guide

1. Solder top components (order: 120R resistor (if required), switches, 4x JST PH 2.0mm, 2x JST XH2.5mm, 2x MicroFit 3.0 2x2, USB connector, Capacitors & attach heatsinks)
2. Attach 1.5mm heat gap filler pad to bottom, cut to size if required using a sharp knife
3. Poke screw holes into the gap filler pads
4. Use M3x8mm screws to attach to bottom of gantry frame (see above)

Note that thermal connection to the 15mm beam is required! Otherwise the Stepper motor controllers might overheat.

Firmware

1. Plug in USB cable and connect 24V power, the green LED on the bottom side (Rev. B and up) must light up. Hold BOOT pushbutton, while tapping the RESET pushbutton and release all buttons. This is the sequence to set the GBB15 into DFU mode.

   IMPORTANT: STMicro decided on the entire STM32G0 series to set the nBOOT_SEL option bit and thus disable the BOOT0 pin by default. This means you would have only one shot at uploading a bootloader, while the flash is empty. If you choose to re-program the bootloader (e.g. other CAN speed), you cannot get into the DFU mode anymore. For enabling the "legacy" BOOT0 pin functionality, you have two options.

   1. You can use STMicro's STM32CubeProgrammer software to disable the nBOOT_SEL option bit by following the screenshot here.

   2. Or if you prefer dfu-util, which is included (or easily installed) in major linux distros (e.g. Raspberry Pi OS), you can run the enable_boot.hex firmware from here. It will clear the nBOOT_SEL option bit from within the firmware, if it is not yet cleared. Use the following commands to upload the file.

          objcopy --input-target=ihex --output-target=binary enable_boot0.hex enable_boot0.bin # Convert hex to binary
          sudo dfu-util -a 0 -d 0483:df11 --dfuse-address 0x08000000:leave -D enable_boot0.bin
      

      After waiting for a second, the BOOT0 pin is now enabled again and you can continue normally.

      NOTE: Before continuing, remember to set the GBB15 into DFU mode again using the BOOT/RESET pushbuttons (see above).

2. Build CanBoot according the instructions on the CanBoot github page. See this image for CanBoot menuconfig settings to use.

3. Build the Klipper firmware according to the instructions on the Klipper github page. See this image for Klipper menuconfig settings to use.

4. Upload CanBoot to the GBB15 using either STM32CubeProgrammer (if you have it installed) or using dfu-util with these commands.

       sudo dfu-util -a 0 -d 0483:df11 --dfuse-address 0x08000000:leave -D out/canboot.bin
   

   The device is now booted into CanBoot mode and can be accessed using the CanBoot tools.

5. Upload the Klipper firmware to the GBB15 using either CanBoot's flashtool.py as described here or Klipper's make flash (uses dfu-util).

   1. Using flashtool.py via CAN. Run these commands from the CanBoot/scripts directory

          python3 flashtool.py -i can0 -q # Check the UUID of the GBB15 board
          python3 flashtool.py -i can0 -f ~/klipper/out/klipper.bin -u <uuid> # Insert UUID here
      

   2. Using make flash via Klipper Makefile. Run this command from the klipper directory.

      NOTE: For this, you need to set the GBB15 into DFU mode again using the BOOT/RESET pushbuttons (see above).

          make flash FLASH_DEVICE=0483:df11
      

Pinout

This image shows the pinout of the GBB15 PCB. The CAN connector layout is compatible to the BigTreeTech EBB36 board (among others).

Klipper configuration

[mcu gantry_mcu]
canbus_interface: can0
canbus_uuid: f7b6d9f26b4a

...

[temperature_sensor chamber]
sensor_type: Generic 3950
sensor_pin: gantry_mcu:PA1 # SMD thermistor on GBB15 PCB
#sensor_pin: gantry_mcu:PA3 # Alternatively, this is STOP1 connector if it is not used otherwise
#sensor_pin: gantry_mcu:PA2 # Alternatively, this is STOP2 connector if it is not used otherwise (for Rev. B and up) 
pullup_resistor: 4700

[temperature_sensor Motor_A]
sensor_type: Generic 3950
sensor_pin: gantry_mcu:PB11 # TH_A on GBB15 PCB
pullup_resistor: 4700

[temperature_sensor Motor_B]
sensor_type: Generic 3950
sensor_pin: gantry_mcu:PB12 # TH_B on GBB15 PCB
pullup_resistor: 4700

[temperature_sensor gantry_temp]
sensor_type: temperature_mcu
sensor_mcu: gantry_mcu
min_temp: 0
max_temp: 100

...

[stepper_y]
step_pin: gantry_mcu:PB2
dir_pin: gantry_mcu:PB1
enable_pin: !gantry_mcu:PB13
endstop_pin: gantry_mcu:PA3 # This is the STOP1 connector on GBB15 PCB
#endstop_pin: gantry_mcu:PA2 # Alternatively, this is STOP2 connector (for Rev. B and up, PC13 on Rev. A)
#endstop_pin: gantry_mcu:PB0 # This is the DIAG pin of the TMC driver for sensorless homing
...

[tmc2209 stepper_y]
uart_pin: gantry_mcu:PA4
sense_resistor: 0.110
...

[stepper_x]
step_pin: gantry_mcu:PB7
dir_pin: gantry_mcu:PB8
enable_pin: !gantry_mcu:PB9
endstop_pin: gantry_mcu:PA2 # This is STOP2 connector (for Rev. B and up, PC13 on Rev. A)
#endstop_pin: gantry_mcu:PA3 # Alternatively, this is the STOP1 connector on GBB15 PCB
#endstop_pin: gantry_mcu:PB5 # This is the DIAG pin of the TMC driver for sensorless homing
...

[tmc2209 stepper_x]
uart_pin: gantry_mcu:PB3
sense_resistor: 0.110
...

"Chamber" thermistor in this configuration is a SMD thermistor on the PCB. It reads probably 15-20°C above the actual chamber temperature, when the stepper motors are enabled and running.

• To get better chamber temp readings, you can use TH_A or TH_B to connect a remote thermistor (in case you don't need those for monitoring the motor temperatures).
• Alternatively you can (mis-)use the STOP1 (All revisions) and STOP2 (Rev. B and up) pins for analog readings. Easiest is a through-hole 100K B3950 NTC crimped into a JST PH2.0 and connected to one of the mentioned header pins.