Timeline for Increase PWM bit resolution
Current License: CC BY-SA 3.0
16 events
| when toggle format | what | by | license | comment | |
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| Aug 1, 2022 at 7:20 | comment | added | Edgar Bonet | @Dima: Probably, but that won't be simple. | |
| Aug 1, 2022 at 3:01 | comment | added | Dima | I'm trying to figure out if PWM resolution on an Atmega168P can be increased on three pins. From what I understand, the 16-bit timer only works with two pins. Is there maybe some way to use two full cycles of the 8-bit timer, using a variable that keeps track of if it is on cycle one or two? A 50% duty cycle would be on for one 8-bit cycle and off for the second. | |
| Mar 7, 2017 at 18:54 | comment | added | davivid | @Edgar Bonet: Thanks for explaining that - the workaround works for me. | |
| Mar 7, 2017 at 17:34 | comment | added | Edgar Bonet |
@davivid: Yes, you cannot have a zero duty cycle. analogWrite16(pin, val) gives a duty cycle of (val+1)/ICR1. As a workaround, Arduino's analogWrite() does if (val == 0) digitalWrite(pin, LOW); else if (val == 255) digitalWrite(pin, HIGH);. But then you cannot get a duty cycle of 1/ICR1...
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| Mar 7, 2017 at 17:03 | comment | added | davivid |
@Edgar Bonet This is great, however I can't seem to fully turn off an LED. I'm using ICR1 = 0x03FF and at 0 I'm seeing a tiny pulse on the scope enough to light the led. Any ideas?
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| Jul 13, 2015 at 14:03 | comment | added | Edgar Bonet | @FlorinAndrei: I do not know the 32u4, but according to the summary datasheet, it should work, as it has two 16-bit timers and "Four PWM Channels with Programmable Resolution from 2 to 16 Bits". | |
| Jul 13, 2015 at 6:48 | comment | added | Florin Andrei | Fantastic answer! But would this work with an ATmega32u4 - as seen on the Arduino Micro? | |
| Jul 1, 2015 at 15:36 | comment | added | Edgar Bonet |
Remove _BV(PB1) and _BV(COM1A1) from setupPWM16(), then change change analogWrite16() so that it only works on pin 10.
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| Jul 1, 2015 at 10:02 | comment | added | KoenR | Am I able to use this with a CAN-bus shield which CS is on port 9? If so, is it only changing this line of code: DDRB |= _BV(PB1) | _BV(PB2); | |
| Jun 18, 2015 at 8:59 | vote | accept | KoenR | ||
| Jun 18, 2015 at 8:18 | comment | added | KoenR | Thank you for the explanation. Edited my question so that it covers these mistakes. So other people can see it directly. Thank you! | |
| Jun 18, 2015 at 7:44 | comment | added | Edgar Bonet |
@KoenR: No, the prescaler has no effect on the resolution, it's purpose is to slow down the counting. Setting the prescaler to 8 will give you a PWM frequency of 30.5 Hz. If you want 13 bit resolution, set ICR1 to 0x1fff, then your frequency will be 1953 Hz (F_CPU/(TOP+1)) with a prescaler at 1.
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| Jun 18, 2015 at 6:51 | comment | added | KoenR | Wow thank you very much, this is exactly what I need. I want my PWM resultion to be the same as my Sensor Resolution. If I change your code to <look at my edit> would it be a 13-bit resultion? If so, what would the frequency be? I will be driving a DC motor with it so 244Hz will be a bit less I guess | |
| Jun 17, 2015 at 19:19 | history | edited | Edgar Bonet | CC BY-SA 3.0 |
Structured the example code.
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| Jun 17, 2015 at 18:17 | history | edited | Edgar Bonet | CC BY-SA 3.0 |
+ example code.
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| Jun 17, 2015 at 16:19 | history | answered | Edgar Bonet | CC BY-SA 3.0 |