LAOS Mainboard v05¶

This page describes which parts you need to build revision 5 of the LAOS mainboard. The revision 5 mainboard is a completely redesigned version of the mainboard. It is still compatible with the older versions but the layout has changed.

The board is designed in KiCad and all design files are available on github: https://github.com/LaosLaser/Hardware/tree/master/laos-board-rev5 .

For a pdf of the schematics see here: https://github.com/LaosLaser/Hardware/blob/master/laos-board-rev5/laos-board.pdf?raw=true

Choices¶

Before ordering the parts a few choices have to be made:
- External stepper drivers or Pololu 1182 stepper drivers. If you are going to use external stepper drivers, you can omit the Pololu drivers and their capacitors (100uF: C9, C10, C11)
- Power source for the mBed: if there is a stable 5V power source available in you laser cutter you can omit the 7805 and bridge VCPU to +5V
- Connectors: HPC's lasers use JST connectors, the footprints of the connectors also allow for 5.08mm pitch connectors like a Phoenix contact MSTBA on the PCB and MSTB on the cable.
- 24V transistor output: Q1 and Q2 are two heavy NPN transistors that can be used to switch external loads. If you don't want to do that you can omit J27, Q1, Q2, R17 and R15.
- SD card or microSD card: since revision 5 there is an option to mount a microSD card holder instead of the full size SD card holder. Where the regular SD card sticks out of the board, the microSD card stays inside the board. The microSD card holder is harder to mount and some microSD cards may not work with the board (SPI support is not mandatory for microSD cards). When in doubt: use the regular one.

Some parts are not (yet) supported in the software and are therefore not neccesary:
- USB connector (J1)
- CAN bus (CAN1, R1, U1, C2)

Buying parts¶

Building the board¶

Configuring the jumpers¶

• J28: Vout for the high current outputs
• J43: Endstops
• J40: VMOT/VCPU bridge
• J12, J19, J25: microstepping
• J3: CPU power from USB
• J41: O1 Source
• J42: O2 source

Testing¶

Connecting your lasercutter¶

• PWM (capacitor)