Can´t get FIFO to Work

[Joao Dullius]

I"m trying to test FIFO to transfer sensor values from one function/thread to other.

This is my current code:

K_FIFO_DEFINE(temp_fifo);

struct data_item_t {
    void *fifo_reserved;   /* 1st word reserved for use by FIFO */
	struct sensor_value temp;
	struct sensor_value hum;
};

struct data_item_t *rx_buf;
struct data_item_t tx_buf;

void print_data(void){
	
	rx_buf = k_fifo_get(&temp_fifo, K_FOREVER);

	printf("HTS221: Temperature: %.1f C\n", sensor_value_to_double(rx_buf->temp));
	printf("HTS221: Relative Humidity: %.1f%%\n", sensor_value_to_double(rx_buf->hum));
	printf("\n");

}

void work_sample(struct k_work *work) {
	
	if (sensor_sample_fetch(hts221) < 0) {
		printf("HTS221 Sensor sample update error\n");
		return;
	}
	sensor_channel_get(hts221, SENSOR_CHAN_AMBIENT_TEMP, &tx_buf.temp);
	sensor_channel_get(hts221, SENSOR_CHAN_HUMIDITY, &tx_buf.hum);	
	k_fifo_put(&temp_fifo, &tx_buf);
   	print_data();
}
K_WORK_DEFINE(my_work, work_sample);

void timer_handler(struct k_timer *timer_id){
	k_work_submit(&my_work);
}
K_TIMER_DEFINE(my_timer, timer_handler, NULL);

I'm getting the following error:

../src/main.c: In function 'print_data':
c:\Work\zephyr-course\sensor_fifo\src\main.c:36:71: error: incompatible type for argument 1 of 'sensor_value_to_double'
   36 |  printf("HTS221: Temperature: %.1f C\n", sensor_value_to_double(rx_buf->temp));
      |                                                                 ~~~~~~^~~~~~
      |                                                                       |
      |                                                                       struct sensor_value
In file included from c:\Work\zephyr-course\sensor_fifo\src\main.c:10:
C:\Work\nrf-tm\v1.9.1\zephyr\include\drivers\sensor.h:659:72: note: expected 'const struct sensor_value *' but argument is of type 'struct sensor_value'
  659 | static inline double sensor_value_to_double(const struct sensor_value *val)
      |                                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
c:\Work\zephyr-course\sensor_fifo\src\main.c:37:77: error: incompatible type for argument 1 of 'sensor_value_to_double'
   37 |  printf("HTS221: Relative Humidity: %.1f%%\n", sensor_value_to_double(rx_buf->hum));
      |                                                                       ~~~~~~^~~~~
      |                                                                             |
      |                                                                             struct sensor_value
In file included from c:\Work\zephyr-course\sensor_fifo\src\main.c:10:
C:\Work\nrf-tm\v1.9.1\zephyr\include\drivers\sensor.h:659:72: note: expected 'const struct sensor_value *' but argument is of type 'struct sensor_value'
  659 | static inline double sensor_value_to_double(const struct sensor_value *val)
      |                                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
At top level:
c:\Work\zephyr-course\sensor_fifo\src\main.c:17:34: warning: 'hum' defined but not used [-Wunused-variable]
   17 | static struct sensor_value temp, hum;
      |                                  ^~~
c:\Work\zephyr-course\sensor_fifo\src\main.c:17:28: warning: 'temp' defined but not used [-Wunused-variable]
   17 | static struct sensor_value temp, hum;
      |                            ^~~~
ninja: build stopped: subcommand failed.

It appears that my FIFO is being completely optimized out...

Any light on this?

[Joao Dullius]

Solved.

sensor_value_to_double expects a pointer:

    printf("HTS221: Temperature: %.1f C\n", sensor_value_to_double(&rx_buf->temp));

    printf("HTS221: Relative Humidity: %.1f%%\n", sensor_value_to_double(&rx_buf->hum));