Controlling a microservo from nRF51822 when BLE is activated

RE: Controlling a microservo from nRF51822 when BLE is activated

James Heires — Sat, 28 Nov 2015 20:23:06 GMT

tumaku, Have you initialized the control input to your servo before applying power? If not, you should, because most DC servos such as the TowerPro SG90 units have an undefined state when power is applied, but no control signal has been set.

RE: Controlling a microservo from nRF51822 when BLE is activated

Asbjørn — Thu, 12 Mar 2015 16:15:08 GMT

This seems fine. Just make sure that PPI channels and timers doesn't overlap with what the softdevice requires.

RE: Controlling a microservo from nRF51822 when BLE is activated

tumaku — Fri, 06 Mar 2015 10:03:46 GMT

The basic Servo routine that I am using in mbed relies on the "core" mbed class PwmOut. I will check if they are using Timer0 there. Trying to reuse the Nordic PWM example, this is the init method that I have created to use PIN 15 as PWM control of the servo. Is this correct?

void pwm_init()
{
    nrf_pwm_config_t pwm_config = PWM_DEFAULT_CONFIG;
    
    pwm_config.mode             = PWM_MODE_MTR_100;
    pwm_config.num_channels     = 1;
    pwm_config.gpio_num[0]      = P0_15;
    
    // Initialize the PWM library
    nrf_pwm_init(&pwm_config);    
}

RE: Controlling a microservo from nRF51822 when BLE is activated

Asbjørn — Thu, 05 Mar 2015 13:02:06 GMT

The PWM example is the best place to start. If your application stops when you activate BLE functionality I would recommend you to check if both your application and softdevice are trying to access and use some of the same resources on the chip. For example timers or PPI channels. Have a look in the S110 Softdevice specification.