Moving Two Things

Learning G-Code is quite interesting: it’s really old, really simple, and yet surprisingly complex if you want to get CNC cuts 100% perfect. Luckily my use-cases are much simpler, but I still would like to move 2 axis concurrently: e.g. move along the x-axis from 0 to 400mm, and rotate the a axis from 0 to 180 degrees so that they start and end together.

Adding a Servo

Step 1 is to connect a servo, which was not as easy as I thought since there’s no dedicated servo connector I can readily use on the DLC32. Luckily there are plenty pins to get GND, 5V and a PWM signal. This is the section I added to the config.yaml:

  a:
    steps_per_mm: 10
    max_rate_mm_per_min: 100000.0
    acceleration_mm_per_sec2: 100000.0
    max_travel_mm: 180.0
    soft_limits: true
    homing:
      cycle: 0
      mpos_mm: 0
      positive_direction: false
    motor0:
      rc_servo:
        pwm_hz: 50
        output_pin: gpio.25
        min_pulse_us: 1000
        max_pulse_us: 2000

IO25 is readily available on the EXP1 connector, so I used 5V, GND and IO25 from EXP1:

EXP1 and EXP2 (unused with FluidNC)

Now I can use G-Code like this:

  • G0A90 to move the servo to the neutral position 90° (assuming 1ms=0°, 2ms=180°). The actual movement depends on the servo. Most move only 90° in total.
  • G1X300A10F200 now does:
    • Move to x=300mm and rotate a to 10° at a feed-rate of 200 mm/minute. If x=100 at the start, this movement will take 1 minute.
    • During the movement, a ?<ENTER> will show the current positions:
?
<Run|MPos:221.533,0.000,0.000,126.500|FS:200,0|Pn:PYZ>
ok
[...about 30 seconds later...]
?
<Idle|MPos:300.000,0.000,0.000,10.000|FS:0,0|Pn:PYZ>
ok

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