Hi,
We have a battery powered wireless sensor working as an OpenThread SED. We have a single push button switch for UI purposes. The design is like this.
The issue is when the switch is pressed the current draw is much higher. We have a long key press of 10 secs and I wanted to improve this battery drain due to switch press.
What I thought was to remove R24 and then dynamically turn on/off the internal pull-up to charge the C7. This way the current drain is only during a small portion of the time per scan cycle.
This is how I tried it.
In coap_client.c
#define SW0_NODE DT_ALIAS(sw0) // Feature 13
static const struct gpio_dt_spec button = GPIO_DT_SPEC_GET_OR(SW0_NODE, gpios, {0});
void main () {
...
ret = dk_buttons_init(on_button_changed);
...
ret = gpio_pin_configure_dt(&button, GPIO_INPUT);
...
}
So after dk_button_init() configuring the pin as input with a pull-up, I disable it after that.
Then I have two k_work items as follows.
static struct k_work_delayable button_off_work, button_scan_work;
...
static void button_scan () {
gpio_pin_configure_dt(&button, GPIO_INPUT | GPIO_PULL_UP); // charge the 100n by enabling internal pull-up
k_work_schedule (&button_off_work, K_MSEC(10)); // schedule to turn off pull-up in 10ms
}
static void button_off () {
gpio_pin_configure_dt(&button, GPIO_INPUT); // turn off input pull-up to reduce current drain
k_work_schedule (&button_scan_work, K_MSEC(100)); // schedule pull-up enable in another 100ms
}
When I grab a scope view across push button I see this as expected.
The signal levels seems within spec (0.9V and 2.1V @ 3V VDD). The power consumption is much better now with respect to previous.
Only issue is I dont get any button change events now!!
I have traced the buttons_scan_fn() in dk_buttons)and_leds.c. It seems like this function gets invoked couple of time initially but then stops.
Any thoughts anyone??
Cheers,
Kaushalya
