OUTPUT_SCALE < OUTPUT_MAX_LIMIT?

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3 years 6 months ago - 3 years 6 months ago #269251 by blazini36
I don't have any cards with a pwmgen enabled to verify but like I said there's no need to guess when you can just open a terminal and type:
Code:
halcmd show pin *pwmgen*

 I will say that now that I look at it the way that section of the doc is written is slightly confusing you're right, the -1.0 to 1.0 thing is the ratio not the pin range. That should have been worded in the doc.
Last edit: 3 years 6 months ago by blazini36. Reason: avoid confusion

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3 years 6 months ago #269288 by tommylight
The last paragraph on last post is a bit off, not frequency, scale, if scale is 35 or 1000.
-
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,

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3 years 6 months ago - 3 years 6 months ago #269305 by blazini36

The last paragraph on last post is a bit off, not frequency, scale, if scale is 35 or 1000.
-
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: 3 years 6 months ago by blazini36.
The following user(s) said Thank You: joekline9, tommylight

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