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PicoCNC First Run Settings

Or, Help! It's not listening to me!

You have put your new PicoCNC board together, built and loaded the firmware but when you hook up a GCode Sender nothing works. You might see something about Alarm depending on the GCode Sender you use. So here are the things you need to do to get it working. 1. Make sure you have 12V for the inputs. 5V from USB is not enough. There is an LED in the lower left of the board that should be lit. If not, you haven't connected 12V so do that now. Either connect a 12V PSU to the nearby terminals or use the jumpers to join the input 12V section to the relay 12V section (and make sure that is also connected to a 12V PSU).

2. Tame Halt, Cycle Start and Feed Hold. Several ways to do this

A) Connect the Halt, Cycle Start and Feed Hold inputs to Normally Closed (NC) switches. This is the recommended approach.

B) Jumper Halt sig pin to ground. This is only temporary to get you past the alarm state.

C) Invert Halt, Cycle Start and Feed Hold signal pin. This makes grblHAL see them as Normally Open switches. Use $14=70 in your GCode Sender's console section. You will then need to use Normally Open (NO) switches on Halt, Cycle Start and Feed Hold inputs.

Because grblHAL encourages good anti Electromagnetic Interference (EMI) practices the default is to use NC switches.

3. Correct the Limit Switches. This is similar to what you did in section 2. You need to decide whether to use NO or NC switches. I encourage you to use NC because they are better for EMI avoidance. If you use NO, you will need to invert the Limit inputs. $5=7 for a 3 Axis Machine or $5=15 for a 4 Axis machine. A moving gantry machine with ganged drivers is a 3 Axis machine from grblHAL's perspective.

4. Set up probe input. You can defer this to when you set up your probe. Generally most probes are NO switches so you should just go ahead and invert it. $6=1 will do it.

That should get you going! The grblHAL wiki has a first run section that goes into more detail. About Me.

I'm Phil Barrett, a long time CNC enthusiast. I run a small company, Brookwood Design, that makes several breakout boards for grblHAL and love to help people get the most out of their CNC machines.


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