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Smart Bluetooth

Anonymous
Not applicable

I need to use all 4 PWM channels and because the way they are connected I had to move the buzzer from P28 to P13 (same hardware pin). The output sound that I am getting now is very distorted. Why ?

Similar issue was already reported with BCM20732 and SDK 1.1 here:

PWN not working on P13/P14 on BCM20732S - SDK 1.1

Also here I don't have any problems with P26, P27, and P28.

This issue is very easy to reproduce, in:

include/Platforms/BCM920737TAG_Q32/platform.h

one can change:

#define GPIO_PIN_BUZZER         28

to:

#define GPIO_PIN_BUZZER         13

and then any sample app (that uses the buzzer) can be used e.g. hello-sensor

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1 Solution
MichaelF_56
Moderator
Moderator

madmax

Note that this discussion has been updated and a we have discovered that there is a way to get all 4 PWMs working on the SIP module: Re: How many PWM channels available in BCM20732S  ?

Regarding the distortion reported above, this was being caused by the clock selection on previous SDK versions as the clock being used for the PWM function was coming out of sleep. SDK 2.1 and later uses the LPO clock, so the issue with distorted volume is not present (i.e. this clock is always running).

The new pwm_tones application within SDK 2.1 and later has also added some comments which better instruct users on the correct utilzation of the PWM function.

vik86 j.t

View solution in original post

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1 Reply
MichaelF_56
Moderator
Moderator

madmax

Note that this discussion has been updated and a we have discovered that there is a way to get all 4 PWMs working on the SIP module: Re: How many PWM channels available in BCM20732S  ?

Regarding the distortion reported above, this was being caused by the clock selection on previous SDK versions as the clock being used for the PWM function was coming out of sleep. SDK 2.1 and later uses the LPO clock, so the issue with distorted volume is not present (i.e. this clock is always running).

The new pwm_tones application within SDK 2.1 and later has also added some comments which better instruct users on the correct utilzation of the PWM function.

vik86 j.t

View solution in original post

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