Different polarity at 2 pins when using PWM.

RE: Different polarity at 2 pins when using PWM.

hmolesworth — Mon, 08 Jun 2020 02:36:33 GMT

Ted, in passing as I am using differential Manchester encoding myself I see you are using nrf_pwm_values_individual_t which requires double the memory of nrf_pwm_values_grouped_t; the only requirement is that for the latter you map the pins to PSEL.OUT[0] and PSEL.OUT[2] instead of PSEL.OUT[0] and PSEL.OUT[1]. Worth doing, since I expect you have found that Manchester encoding with differential PWM requires large memory buffers compared with single-ended SPI.

RE: Different polarity at 2 pins when using PWM.

Amanda Hsieh — Wed, 01 Apr 2020 06:51:06 GMT

Hi Ted,

Please verify the answer if it can fix the issue. Thanks.

-Amanda H.

RE: Different polarity at 2 pins when using PWM.

Ted — Wed, 01 Apr 2020 02:45:47 GMT

hmolesworth It is OK. I make a mistake. You are right. Thank you very much.

RE: Different polarity at 2 pins when using PWM.

Ted — Wed, 01 Apr 2020 01:31:50 GMT

hmolesworth I change my code as follows. But the output is still Fig-1. What's wrong with my program?

.output_pins =
{pin_125K_OUT_PLUS | NRF_DRV_PWM_PIN_INVERTED,
pin_125K_OUT_MINUS,
},

.output_pins =
{pin_125K_OUT_MINUS| NRF_DRV_PWM_PIN_INVERTED,
pin_125K_OUT_PLUS ,
},

RE: Different polarity at 2 pins when using PWM.

hmolesworth — Tue, 31 Mar 2020 16:16:41 GMT

Both pins are set to the same active state using the above code, simply change one pin by removing NRF_DRV_PWM_PIN_INVERTED depending on which order you require. In this code snippet PLUS will be active high and MINUS active low:

.output_pins =
{pin_125K_OUT_PLUS | NRF_DRV_PWM_PIN_INVERTED,
 // pin_125K_OUT_MINUS,
 pin_125K_OUT_MINUS,
},