how do I change PWM port to 1 on example "low_power_pwm"

Question

Hi,
I have Design a new product based on the NRF52840 I am trying to get the lcd up and running so first thing is the pwm for the backlight. I am using pin 1.08 for the pwm. but I seem to have problem trying to convert LED1 to Port 1 I setup the Low_power_pwm example project and changed the defined board to Custom_board and copied PCA10056.h and renamed it custom_board it compiles fine and works but once I try to change the definition of LED1 It now compiles but will NOT toggle the output P1.8 
 here is the part of custom_board.h that I changed: 
 original:
/ LEDs definitions for PCA10056
#define LEDS_NUMBER 4 
 #define LED_1 NRF_GPIO_PIN_MAP(0,13)
#define LED_2 NRF_GPIO_PIN_MAP(0,14)
#define LED_3 NRF_GPIO_PIN_MAP(0,15)
#define LED_4 NRF_GPIO_PIN_MAP(0,16) 
 #define LEDS_ACTIVE_STATE 0 
 #define LEDS_LIST { LED_1, LED_2, LED_3, LED_4 } 
 #define LEDS_INV_MASK LEDS_MASK 
 #define BSP_LED_0 13
#define BSP_LED_1 14
#define BSP_LED_2 15
#define BSP_LED_3 16 
 I made two changes:
#define LED_1 NRF_GPIO_PIN_MAP(1,8)
and the second change
#define BSP_LED_0 8 
 the original compiled and worked in the Preview -DK using P0.13
after making this change it compiled and I downloaded it to my board and But I have NO output on port 1.8 
 What am I missing ?

FormerMember · Accepted Answer

To get the correct pin numbers for pin P1.x, you can use ´NRF_GPIO_PIN_MAP()´in nrf_gpio.h.

For example, pin P1.08:

#define PIN_D7    NRF_GPIO_PIN_MAP(1,8)

By porting P1.8 this way, the value of PIN_D7 is 40 (32+8).

However, low_power_pwm_init() requires a bit mask, which is a uint32_t. In that case, P1.08 is pin 8 on port 1:

low_power_pwm_config.bit_mask       = (1 <<  NRF_GPIO_PIN_MAP(0,8)); 
low_power_pwm_config.p_port         = NRF_P1;

In low_power_pwm_init(), when configuring the output pin(s), the port is not taken care of. Therefore, to make the pwm driver work with port 1 pins, nrf_gpio_port_dir_output_set() has to be used to configure the pin in low_power_pwm_init():

 nrf_gpio_port_dir_output_set(p_pwm_config->p_port,p_pwm_instance->bit_mask); //todo
    //while (bit_mask)
    //{
    //    if (bit_mask & 0x1UL)
    //    {
    //        //nrf_gpio_cfg_output(pin_number);
    //    }
    //
    //    pin_number++;
    //    bit_mask >>= 1UL;
    //}

Igor · Answer

NRF SDK 16.0.0 also has an issue with low power PWM on port 1. 
 low_power_pwm.c, line 188 should be changed from nrf_gpio_cfg_output(pin_number); to nrf_gpio_cfg_output(NRF_GPIO_PIN_MAP(p_pwm_instance->p_port==NRF_P1,pin_number)); 
 Proper usage is then: #define LED_1 NRF_GPIO_PIN_MAP(1,14) // port 1, pin 14

low_power_pwm_config_t pwm_config;
pwm_config.active_high = LEDS_ACTIVE_STATE;
pwm_config.bit_mask =PIN_MASK(LED_1);
pwm_config.p_port = PIN_PORT(LED_1); 
 
 P.S. There is another Low Power issue present in SDK 16.0.0 https://devzone.nordicsemi.com/f/nordic-q-a/29076/low_power_pwm-duty_cycle-seems-buggy https://devzone.nordicsemi.com/f/nordic-q-a/29076/low_power_pwm-duty_cycle-seems-buggy

how do I change PWM port to 1 on example "low_power_pwm"

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