# OUTPUT_SCALE < OUTPUT_MAX_LIMIT?

17 Apr 2023 15:10 - 17 Apr 2023 15:12 #269305

The last paragraph on last post is a bit off, not frequency, scale, if scale is 35 or 1000.
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PWM = pulse width modulation
PDM = pulse duration modulation
PWM cam theoretically have any frequency, and this has nothing to do with scaling, just the speed of the pulses.
Scaling changes how long should those pulses be, regardless of frequency,

Careful now, you made a mistake there too. Pulse Duration Modulation covers both Pulse Width Modulation and Pulse Density Modulation PDM in hostmot2 has predefined slot lengths based on the frequency. The input determines whether to fill the slot with a high pulse or a low pulse, that's density modulation.

But yeah what I said was wrong, I'll probably edit that post so it doesn't confuse anyone. It's simple math but something about the way it's implemented keeps confusing me, especially when I posting late at night after working on something else. I don't use the hm2 pwmgens for anything so I'll consider this a learning experience for myself too.

For all intensive purposes on a spindle, pwm scale should be the maximum RPM. The goal is to reach a duty cycle of 100% expressed as 1.0.
So if DC=value/scale then
Max RPM=2800(scale)
Commanded value=2800
2800/2800=1(DC) or 100% spindle speed

Max RPM=2800(scale)
Commanded value=1400
1400/2800=0.5(DC) or 50% spindle speed
Last edit: 17 Apr 2023 15:12 by blazini36.
The following user(s) said Thank You: joekline9, tommylight