The WFI call works, it just receives an interrupt almost immediately after it is called, which causes the WFI call to stop blocking and then execution continues to the next line.
You could safely remove everything below // Go to sleep which would allow the main function to return. The AON timer would still execute its callback. However, there are a couple of potential downsides to this approach:
- This would not allow the SAMB11 to transition to a lower power mode.
- This removes your while-loop at the end of main. In its current state, the while-loop isn't needed, but you might have plans to add code to it later.
Here is an example that configures the AON, configures the SAMB11 to use low power modes, and then loops waiting for platform and/or BLE events. Currently there are no events for the loop to receive. If you want the loop to receive events then you could modify the AON callback to post an event with the at_ble_event_user_defined_post function or modify main() to configure the BLE module before entering the loop.
Use the ASF Wizard to add any of the BLE modules to your project in order to compile this example.
#include <asf.h>
#include "platform.h"
// Configure LED
static void configure_gpio_pins(void)
{
struct gpio_config config_gpio_pin;
gpio_get_config_defaults(&config_gpio_pin);
config_gpio_pin.direction = GPIO_PIN_DIR_OUTPUT;
gpio_pin_set_config(LED_0_PIN, &config_gpio_pin);
gpio_pin_set_output_level(LED_0_PIN, LED_0_INACTIVE);
}
// Callback Func to toggle LED
static bool led_is_on = false;
static void aon_sleep_timer_callback(void)
{
configure_gpio_pins();
if(led_is_on) {
gpio_pin_set_output_level(LED_0_PIN, LED_0_INACTIVE);
led_is_on = false;
} else {
gpio_pin_set_output_level(LED_0_PIN, LED_0_ACTIVE);
led_is_on = true;
}
}
// Configure Timer to fire periodically
static void configure_aon_sleep_timer(void)
{
struct aon_sleep_timer_config config_aon_sleep_timer;
aon_sleep_timer_get_config_defaults(&config_aon_sleep_timer);
config_aon_sleep_timer.counter = 32000; // Wait about 1 sec
config_aon_sleep_timer.mode = AON_SLEEP_TIMER_RELOAD_MODE;
aon_sleep_timer_init(&config_aon_sleep_timer);
}
// Configure Callback and enable Interrupt
static void configure_aon_sleep_timer_callback(void)
{
aon_sleep_timer_register_callback(aon_sleep_timer_callback);
NVIC_EnableIRQ(AON_SLEEP_TIMER0_IRQn);
}
int main(void)
{
// Setup Clock
system_clock_config(CLOCK_RESOURCE_XO_26_MHZ, CLOCK_FREQ_26_MHZ);
plf_drv_status plf_status;
if((plf_status = platform_driver_init()) == STATUS_SUCCESS) {
// Setup LED and Timer
configure_gpio_pins();
configure_aon_sleep_timer();
configure_aon_sleep_timer_callback();
// wait for timer to be active
while(!aon_sleep_timer_sleep_timer_active());
// Go to sleep
release_sleep_lock();
while(true) {
// Replace platform_event_wait with at_ble_event_get if you would like to read the received event.
plf_status = platform_event_wait(0);
}
}
}
Regarding WFI, the following example shows how to turn off most of the interrupts and use WFI to block main(). The LED will toggle every time an interrupt is received. I don't recommend using this as I'm not sure why these interrupts are enabled initially. This is just intended to show how WFI can block on a SAMB11.
#include <asf.h>
#include "platform.h"
// Configure LED
static void configure_gpio_pins(void)
{
struct gpio_config config_gpio_pin;
gpio_get_config_defaults(&config_gpio_pin);
config_gpio_pin.direction = GPIO_PIN_DIR_OUTPUT;
gpio_pin_set_config(LED_0_PIN, &config_gpio_pin);
gpio_pin_set_output_level(LED_0_PIN, LED_0_INACTIVE);
}
// Callback Func to toggle LED
static bool led_is_on = false;
static void toggle_led(void)
{
configure_gpio_pins();
if(led_is_on) {
gpio_pin_set_output_level(LED_0_PIN, LED_0_INACTIVE);
led_is_on = false;
} else {
gpio_pin_set_output_level(LED_0_PIN, LED_0_ACTIVE);
led_is_on = true;
}
}
int main(void)
{
// Setup Clock
system_clock_config(CLOCK_RESOURCE_XO_26_MHZ, CLOCK_FREQ_26_MHZ);
// Clear all interrupts.
NVIC->ICER[0] = 0xFFFFFFFF;
// During testing, interrupts were received about once per second; stopped receiving interrupts (LED stopped flashing) after about 2 minutes.
int loop_count = 0;
while(true) {
__WFI();
toggle_led();
}
}
