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Wrong frequency #1

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americodias opened this issue Sep 25, 2021 · 4 comments
Closed

Wrong frequency #1

americodias opened this issue Sep 25, 2021 · 4 comments
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bug Something isn't working

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@americodias
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americodias commented Sep 25, 2021 •
edited

Describe the bug

I'm getting wrong results.

Steps to Reproduce

I'm running a modified version of your PWM_Multi example on a Arduino Nano RP2040 Connect.

Expected behavior

9 kHz output

Actual behavior

I get 11.81kHz according to the oscilloscope.

However if I change the code to 10kHz for instance, I get 10kHz.

Debug log

Starting PWM_Multi on Nano RP2040 Connect
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	4	9000.00		50[PWM] bestfit_PWM_Freq = 8999.28, PWM_Freq_diff = 0.72, Top_p_1 - 1 = 13889, vsDiv/16.0 = 1.00
[PWM] bestfit_PWM_Freq = 8999.93, PWM_Freq_diff = 0.07, Top_p_1 - 1 = 13888, vsDiv/16.0 = 1.00
[PWM] bestfit_PWM_Freq = 9000.01, PWM_Freq_diff = 0.01, Top_p_1 - 1 = 10581, vsDiv/16.0 = 1.31
[PWM] PWM_Freq = 9000.00, _actualFrequency = 9000.01, PWM_Freq_diff = 0.01
[PWM] TOP = 1DIV = 1
		9000.01
[PWM] 
TOP = 10581, DIV = 1, CPU_freq = 125000000
=============================================================

Screenshots

Oscilloscope screenshot here.
@khoih-prog
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Hi @americodias

Thanks for testing and using the library.

I'm able to duplicate the bug, which seems to happen when freq = 9000-9999Hz

I'll definitely spend time to investigate and fix this interesting bug. Hopefully, the culprit is something in the library, not in the chip.

In the mean time, I'd appreciate if you can make some more tests to see where else the similar issue happens.

Best,

@khoih-prog
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khoih-prog commented Sep 25, 2021 •
edited

Hi,

Already found and fixed the bug, the culprit is the so-called best-fit algorithm. I don't use it now and just use my simple calculation.
Everything will be OK as the following debug terminal shows.

Will publish a new version by tomorrow, with your contribution noted.

Best Regards,

===

Starting PWM_Multi on RaspberryPi Pico
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	2	200000.00		50[PWM] _PWM_config.top =624, _actualFrequency =200000.00
		200000.00
[PWM] TOP = 624, DIV = 1, CPU_freq = 125000000       =================> PWM = 200000 !!!
=============================================================



Starting PWM_Multi on RaspberryPi Pico
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	2	8999.00		50[PWM] _PWM_config.top =13889, _actualFrequency =8999.00
		8999.00
[PWM] TOP = 13889, DIV = 1, CPU_freq = 125000000       =================> PWM = 8999.2 !!!
=============================================================


Starting PWM_Multi on RaspberryPi Pico
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	2	9000.00		50[PWM] _PWM_config.top =13887, _actualFrequency =9000.00
		9000.00
[PWM] TOP = 13887, DIV = 1, CPU_freq = 125000000       =================> PWM = 9000.576 !!!
=============================================================


Starting PWM_Multi on RaspberryPi Pico
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	2	2000.00		50[PWM] _PWM_config.top =62499, _actualFrequency =2000.00
		2000.00
[PWM] TOP = 62499, DIV = 1, CPU_freq = 125000000       =================> PWM = 2000 !!!
=============================================================


Starting PWM_Multi on RaspberryPi Pico
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	2	1000.00		50[PWM] _PWM_config.top =12499, _actualFrequency =1000.00
		1000.00
[PWM] TOP = 12499, DIV = 10, CPU_freq = 125000000       =================> PWM = 1000 !!!
=============================================================

Starting PWM_Multi on RaspberryPi Pico
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	2	1000.00		50[PWM] _PWM_config.top =12499, _actualFrequency =1000.00
		1000.00
[PWM] TOP = 12499, DIV = 10, CPU_freq = 125000000       =================> PWM = 1000 !!!
=============================================================



Starting PWM_Multi on RaspberryPi Pico
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	2	500.00		50[PWM] _PWM_config.top =24999, _actualFrequency =500.00
		500.00
[PWM] TOP = 24999, DIV = 10, CPU_freq = 125000000       =================> PWM = 500 !!!
=============================================================


Starting PWM_Multi on RaspberryPi Pico
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	2	50.00		50[PWM] _PWM_config.top =24999, _actualFrequency =50.00
		50.00
[PWM] TOP = 24999, DIV = 100, CPU_freq = 125000000       =================> PWM = 50 !!!
=============================================================


Starting PWM_Multi on RaspberryPi Pico
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	2	10.00		50[PWM] _PWM_config.top =62499, _actualFrequency =10.00
		10.00
[PWM] TOP = 62499, DIV = 200, CPU_freq = 125000000       =================> PWM = 10 !!!
=============================================================


Starting PWM_Multi on RaspberryPi Pico
RP2040_PWM v1.0.0
=============================================================
Index	Pin	PWM_freq	DutyCycle	Actual Freq
=============================================================
0	2	7.50		50[PWM] _PWM_config.top =65358, _actualFrequency =7.00
		7.00
[PWM] TOP = 65358, DIV = 255, CPU_freq = 125000000       =================> PWM = 7.5 !!!
=============================================================

@americodias
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Hi @khoih-prog,

That was fast! Thank you for creating this library and for the quick fix!

I will use this library for an ongoing project and will let you know if I find any other issues.

Kind regards,
Américo

khoih-prog added a commit that referenced this issue Sep 25, 2021
@khoih-prog
v1.0.1 to fix bug generating wrong frequencies
24edb66 
### Releases v1.0.1

1. Fix bug generating wrong frequency. See [Wrong frequency #1](#1)
khoih-prog added a commit that referenced this issue Sep 25, 2021
@khoih-prog
v1.0.1 to fix bug generating wrong frequencies
a8e5cff 
### Releases v1.0.1

1. Fix bug generating wrong frequency. See [Wrong frequency #1](#1)
@khoih-prog
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Hi @americodias

The new RP2040_PW releases v1.0.1 has just been published

Your contribution has been noted in Contributions and Thanks

Thanks to the contributions of users like you, the library will have good chance to be better and better, with less and less bugs.

Releases v1.0.1

  1. Fix bug generating wrong frequency. See Wrong frequency #1

@khoih-prog khoih-prog added the bug Something isn't working label Sep 25, 2021
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@americodias @khoih-prog