clock down to 64khz

src/buttons.c

@@ -24,12 +24,12 @@ static void button_timer_callback(struct btstack_timer_source* ts) {
 	if (gpio_get(BUTTON_PIN_POWER)) {
 		if (bt_connected) {
 			printf("=> Ignoring input, bluetooth connected.\n");
-		} else if (current_power == 0) {
-			printf("= Resuming:   %i%% -> %i%%\n", current_power, resume_power);
+		} else if (target_power == 0) {
+			printf("= Resuming:   %i%% -> %i%%\n", target_power, resume_power);
 			state_set_power(resume_power);
 		} else {
-			printf("= Suspending: %i%% -> %i%%\n", current_power, resume_power);
-			resume_power = current_power;
+			printf("= Suspending: %i%% -> %i%%\n", target_power, resume_power);
+			resume_power = target_power;
 			state_set_power(0);
 		}
 	}
@@ -37,22 +37,22 @@ static void button_timer_callback(struct btstack_timer_source* ts) {
 	if (gpio_get(BUTTON_PIN_PLUS)) {
 		if (bt_connected) {
 			printf("+> Ignoring input, bluetooth connected.\n");
-		} else if (current_power <= (100 - BUTTON_STEP)) {
-			printf("+ Increasing power: %i%% -> %i%%\n", current_power, current_power + BUTTON_STEP);
-			state_set_power(current_power + BUTTON_STEP);
+		} else if (target_power <= (100 - BUTTON_STEP)) {
+			printf("+ Increasing power: %i%% -> %i%%\n", target_power, target_power + BUTTON_STEP);
+			state_set_power(target_power + BUTTON_STEP);
 		} else {
-			printf("+ Increasing power: %i%% -> %i%%\n", current_power, 100);
+			printf("+ Increasing power: %i%% -> %i%%\n", target_power, 100);
 			state_set_power(100);
 		}
 	}
 	if (gpio_get(BUTTON_PIN_MINUS)) {
 		if (bt_connected) {
 			printf("-> Ignoring input, bluetooth connected.\n");
-		} else if (current_power >= BUTTON_STEP) {
-			printf("- Reducing power: %i%% -> %i%%\n", current_power, current_power - BUTTON_STEP);
-			state_set_power(current_power - BUTTON_STEP);
+		} else if (target_power >= BUTTON_STEP) {
+			printf("- Reducing power: %i%% -> %i%%\n", target_power, target_power - BUTTON_STEP);
+			state_set_power(target_power - BUTTON_STEP);
 		} else {
-			printf("- Reducing power: %i%% -> %i%%\n", current_power, 0);
+			printf("- Reducing power: %i%% -> %i%%\n", target_power, 0);
 			state_set_power(0);
 		}
 	}

src/main.c

@@ -1,11 +1,11 @@
 #include "btstack.h"
+#include "buttons.h"
 #include "hci_dump.h"
 #include "hci_dump_segger_rtt_stdout.h"
 #include "pico/btstack_cyw43.h"
 #include "pico/cyw43_arch.h"
 #include "pico/stdlib.h"
 #include "state.h"
-#include "buttons.h"
 #include "stdio_rtt.h"
 #include "vibe_bt.h"
 #include <stdio.h>
@@ -31,8 +31,12 @@ int main() {
 	stdio_init_all();
 	stdio_rtt_init();
 
+	sleep_ms(1000);
+	printf("Underclocking CPU...\n");
+	set_sys_clock_khz(64000, true);
+
 	if (cyw43_arch_init()) {
-		printf("CYW43 init failed");
+		printf("CYW43 init failed\n");
 		return -1;
 	}
 

src/state.c

@@ -1,4 +1,5 @@
 #include "state.h"
+#include "btstack.h"
 #include "hardware/pwm.h"
 #include "pico/stdlib.h"
 
@@ -8,6 +9,30 @@
 static int pwm_slice = 0;
 
 uint8_t current_power = 0;
+uint8_t target_power = 0;
+
+#define RAMP_PERIOD_MS 100
+#define RAMP_STEP 50
+
+// Timer and callback for ramping power. Jumping ~50% power or more in one go kills the
+// chip with electrical ripples, so be a bit gentle about it.
+static btstack_timer_source_t ramp_timer;
+static void ramp_timer_callback(struct btstack_timer_source* ts) {
+	if (current_power != target_power) {
+		if (current_power < target_power - RAMP_STEP) {
+			current_power += RAMP_STEP;
+		} else if (current_power > target_power + RAMP_STEP) {
+			current_power -= RAMP_STEP;
+		} else {
+			current_power = target_power;
+		}
+		pwm_set_chan_level(pwm_slice, PWM_CHAN_A, current_power);
+		pwm_set_chan_level(pwm_slice, PWM_CHAN_B, current_power);
+	}
+
+	btstack_run_loop_set_timer(ts, RAMP_PERIOD_MS);
+	btstack_run_loop_add_timer(ts);
+}
 
 void state_init() {
 	pwm_slice = pwm_gpio_to_slice_num(PWM_PIN_0);
@@ -18,13 +43,14 @@ void state_init() {
 	pwm_set_wrap(pwm_slice, 99);
 	state_set_power(0);
 	pwm_set_enabled(pwm_slice, true);
+
+	ramp_timer.process = ramp_timer_callback;
+	ramp_timer.process(&ramp_timer);
 }
 
 void state_set_power(uint8_t power) {
-    if (power > 100) {
-        power = 100;
-    }
-    current_power = power;
-	pwm_set_chan_level(pwm_slice, PWM_CHAN_A, power);
-	pwm_set_chan_level(pwm_slice, PWM_CHAN_B, power);
+	if (power > 100) {
+		power = 100;
+	}
+	target_power = power;
 }

src/state.h

@@ -5,11 +5,13 @@
 
 // Current power level, 0-100.
 extern uint8_t current_power;
+// Target power level (that we're ramping to), 0-100.
+extern uint8_t target_power;
 
 // Initialize wand state.
 void state_init();
 
-// Set the wand's power, 0-100.
+// Set the wand's target power, 0-100.
 void state_set_power(uint8_t power);
 
 #endif