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Update WIRING.md

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Thaddeus Hughes
2026-05-26 12:37:12 -05:00
parent e90aef454c
commit 487f47b023
1 changed files with 19 additions and 26 deletions
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docs/WIRING.md
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@@ -18,10 +18,10 @@ This is how I have my LinuxCNC machine wired. I put a linuxCNC box in place of a
The encoders for both motors and the standard TRAK encoders use the same Amphenol CPC connector.
The encoders are differential 5V output. They might have an index pulse but I wasn't using it. The Z axis has the same pinout.
The encoders are differential 5V output. They might have an index pulse but I wasn't using it. The Z axis has the same pinout. Peak-peak voltage is 2.7V.
| Pin | Signal | Color (in PC) |
| --- | ------ | ------------- |
| --- | -------- | ------------- |
| 1 | B- | White |
| 2 | 5V | Red |
| 3 | B+ | Blue |
@@ -30,9 +30,9 @@ The encoders are differential 5V output. They might have an index pulse but I wa
| 6 | N/C | |
| 7 | N/C | |
| 8 | N/C | |
| 9 | GND | Black |
| 10 | GND | Black |
| 11 | GND | Black |
| 9 | GND/SHLD | Black |
| 10 | GND/SHLD | Black |
| 11 | GND/SHLD | Black |
| 12 | A- | Yellow |
| 13 | GND | Black |
| 14 | A+ | Green |
@@ -170,19 +170,12 @@ A custom `M101` and `M102` g code enables/disables the z-axis.
- `output-type 1` (PWM + Direction pins)
- `offset-mode 1` → locked anti-phase / bipolar single-signal: duty cycle directly encodes signed command
- `scale = OUTPUT_SCALE`: X = +1, Y = -1, Z = -1 (sign flips drive polarity to match wiring)
- Duty cycle = `(value/scale + 1) / 2`
- peak-peak voltage of 3.3V from the TRAK CNC II control
| Commanded value | Duty cycle | Meaning |
| --------------- | ---------- | ------------ |
| -1.0 | 0 % | full reverse |
| -0.5 | 25 % | half reverse |
| 0.0 | **50 %** | stop |
| +0.5 | 75 % | half forward |
| +1.0 | 100 % | full forward |
When the enable line is deasserted the pwmgen output is forced off (not 50%), so the amp sees a distinct disabled state vs. "commanded zero". You can hear the drives hum/whine at the 50% state.
**WARNING: ENABLING THE DRIVE WITH THE PWM DISCONNECTED WILL SHOW AS A 0% DUTY CYCLE - CAUSING THE DRIVE TO RUN FULL REVERSE!**
My notes say that setting duty cycle to 0 or 100% cause the drive to disable. I'm not sure if this is the case or not. I don't know exactly what the functional band of the PWM is.
### Enable