how to change gpio pin voltage/current levels

RE: how to change gpio pin voltage/current levels

lcj — Wed, 04 Sep 2024 00:49:42 GMT

What were the entries in your overlay?

RE: how to change gpio pin voltage/current levels

Sigurd — Wed, 01 Mar 2017 12:35:36 GMT

To configure your desired period/frequency you can change either the base frequency or the top value. The desired pwm frequency is given by the formula F(pwm) = F(base_clock) / top_value. Note that the max top_value is 32767.

RE: how to change gpio pin voltage/current levels

saiteja — Wed, 01 Mar 2017 09:37:59 GMT

Hi i made BS_LED_0 pin as PWM and changing the frequency by changing .base_clock frequency mode in nrf_drv_pwm_config_t so that i can observe increase and decrease of the light intensity of LED. is this is the correct way to operate pancake motor vibration levels. and what is the purpose of .top_value in nrf_drv_pwm_config_t. thank you.

RE: how to change gpio pin voltage/current levels

AmbystomaLabs — Tue, 28 Feb 2017 14:45:02 GMT

Oh, I just remembered that when I wrote the updated DTM code for PA/LNA support I did a version with a timer on the PPI. Just look for my posting on DTM for the code. It should be easy for you to copy out the timer bit and reuse it for your application.

RE: how to change gpio pin voltage/current levels

AmbystomaLabs — Tue, 28 Feb 2017 14:41:29 GMT

There are a couple of pwm examples in the SDK. Also I have seen numerous postings on the blog with pwm code. But in short, a pwm is just a timer tied to the gpio. You set the length of the timer (how long it can actually count for until it starts back at 0) and you set the amount of time it counts until it turns off the gpio. There are several built in hardware timers on the nRF. So, it goes as: the timer starts, gpio goes high, timer hits your number, gpio turns off, timer keeps running until it hits end, timer goes back to zero and starts over. In this manner you can set any duty cycle for the output you wish. If you are running other code you probably want a solution that doesn't bother the processor to do the pwm. Nordic allow you to tie timers/counters to the PPI and gpio to facilitate a pwm that runs independent of the processor.

RE: how to change gpio pin voltage/current levels

saiteja — Tue, 28 Feb 2017 14:31:04 GMT

hi, Thank you for response. i am using FET to drive the motor the problem is i do not know how to drive the pin as PWM. if i drive the pin as PWM what is the output of that pin.

RE: how to change gpio pin voltage/current levels

AmbystomaLabs — Tue, 28 Feb 2017 14:25:22 GMT

You can't drive this motor directly from the nRF. The spec sheet says it draws 100mA. The nRF52 can provide max 10mA in high drive mode. Also there is no DAC capability with nRF52. GPIO are either on or off. The only solution you can do is drive the pin as PWM and through a low pass filter use a fet or bjt to drive the motor.