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How to have 3 PWMs by using app_pwm.c ?

Sam Lin over 9 years ago

Hi All,

I want to have 3 PWMs by using app_pwm.c lib (in SDK 9.0.0). But from doc each instance takes 2 ppi plus 2 plus per channel.

Means 3 PWMS needs 2 instances.

first instance: 2 + 2 x 2 = 6 2nd instacne: 2+ 2 x 1 = 4

so when i init 2nd PWM instance I got NO_MEM error.

Any good idea about this ?

0 Sam Lin over 9 years ago

I realized that the S130/headers/nrf_sd_def.h limit user ppi location to channel 0-7. If I hack the SD_PPI_CHANNELS_USED to 0xFF0FC00uL to allow user allocate ppi to channel 8,9 it passes.

I want to know if this is a hard limitation or not.
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0 Stefan Birnir Sverrisson over 9 years ago

Hi Sam

The application can use PPI channels 0-13 when using S110, because the S110 reserves PPI channels 14-31 when enabled, see S110 Softdevice Specification 2.0, section 11.5. If you have no softdevice enabled than you can use PPI channels 0-15 for the application.
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0 cnchen over 9 years ago in reply to Stefan Birnir Sverrisson

Hi, a simple follow-up. so there is no other way to use 3 PWMs when SoftDevice is enabled? (Except the hack provided by Lin above)
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