Using a diode laser with grblHAL

Diode lasers are becoming quite popular and recently ones with 30 and 40 watt laser power have been introduced. I expect this trend to continue. A lot of CNCers are adding them to CNC routers along with the spindle. Here's how to connect and use them with grblHAL.

The typical Diode Laser consists of 2 parts - the actual diode and the laser controller. Some have the controller directly mounted on the laser body and other have them separate. Personally, I prefer separate as that moves the two heat generating parts away from each other which makes it easier to cool. It may come with a power supply unit though the one I bought did not. The laser controller not only drives the diode but also manages the power and PWM control input.

Connecting the diode laser

Using one with grbHAL is fairly straight forward though not every laser diode is the same. Basically, you need identify the PWM input of the laser controller and connect that to the PWM terminal of your grblHAL board. On the PicoCNC and T41U5XBB breakout boards they are in the upper left corner of the boards and labeled PWM. And, of course, the laser controller, power supply and breakout board need to have common grounds. Connect the ground terminal near the PWM terminal to the PSU ground terminal and also connect the laser controller to the PSU ground terminal. Do not daisy chain them. You will need to supply the laser controller with the appropriate voltage PSU. Mine takes 12V and I use the same PSU that powers the board. The higher power lasers use 24V. On some laser controllers, the PWM pin may be labeled TTL and have + and - pins. The - pin is ground and the + pin is the PWM input. Note: there is at least one report of the TTL pins being labeled backwards. The + pin is ground and - pin is PWM.

Mounting the laser diode

There are a lot of ways to do this. Some people mount them on one side of the spindle. This allows you to have both the spindle and laser on the machine and ready to be used. The disadvantage of that, especially on smaller CNC machines, is that it reduces your effective work envelope. I 3D