Fix buzzer frequency calculation

src/buzzer.c

@@ -8,7 +8,7 @@
 
 #include "buzzer.h"
 
-#define FREQ_BASE 24414063  // round(125 MHz [CPU frequency] * 100 [scaling] / 512 [PWM steps])
+#define FREQ_BASE 3906250  // round(125 MHz [CPU frequency] * 16 [scaling] / 512 [PWM steps])
 
 uint m_slice_num;
 
@@ -23,14 +23,14 @@ void buzzer_init(void)
 	pwm_set_clkdiv_int_frac(m_slice_num, 244, (14 << 4) / 100); // 125 MHz / 244.14 / 512 = 1 kHz
 	gpio_set_function(BUZZER_PIN, GPIO_FUNC_PWM);
 	pwm_set_wrap(m_slice_num, 512);
-	pwm_set_chan_level(m_slice_num, PWM_CHAN_B, 1 * 512 / 100);
+	pwm_set_chan_level(m_slice_num, PWM_CHAN_B, 1 * 512 / 100); // 1% duty cycle is sufficient for full voltage swing
 }
 
 void buzzer_on(uint16_t freq_hz)
 {
-	uint32_t divider_x100 = FREQ_BASE / freq_hz; // = 100 * 125e6 / 512 / freq_hz
+	uint32_t divider_x16 = FREQ_BASE / freq_hz; // = 16 * 125e6 / 512 / freq_hz
 
-	pwm_set_clkdiv_int_frac(m_slice_num, divider_x100 / 100, divider_x100 % 100);
+	pwm_set_clkdiv_int_frac(m_slice_num, divider_x16 / 16, divider_x16 % 16);
 	gpio_set_function(BUZZER_PIN, GPIO_FUNC_PWM);
 	pwm_set_enabled(m_slice_num, true);
 }

src/main.c

@@ -174,33 +174,36 @@ static void update_countdown_fsm(uint32_t time_ms)
 					sseg_set_pwm_times(0, 255, 0);
 					sseg_set_pwm_times(1, 255, 0);
 					sseg_set_pwm_times(2, 255, 0);
+
+					buzzer_on(2963);
 					break;
 
 				case 500:
 					sseg_set_char(0, '#', false);
-					buzzer_on(1000);
+					buzzer_on(3951);
 					break;
 
 				case 1000:
 					sseg_set_char(1, '|', false);
-					buzzer_on(1414);
+					buzzer_on(2963);
 					break;
 
 				case 1500:
 					sseg_set_char(1, '#', false);
-					buzzer_on(2000);
+					buzzer_on(1976);
 					break;
 
 				case 2000:
 					sseg_set_char(2, '|', false);
-					buzzer_on(2828);
+					buzzer_on(2963);
 					break;
 
 				case 2500:
 					sseg_set_char(2, '#', false);
-					buzzer_on(4000);
+					buzzer_on(3951);
 					break;
 
+				case 200:
 				case 700:
 				case 1200:
 				case 1700:
@@ -254,6 +257,9 @@ static void update_countdown_fsm(uint32_t time_ms)
 				if((m_countdown_off_time - time_ms) > 10 * ONE_HOUR) {
 					m_countdown_off_time = time_ms + 10 * ONE_HOUR;
 				}
+
+				// ensure the buzzer is off after the time was extended
+				buzzer_off();
 			}
 
 			// beep codes
@@ -311,34 +317,39 @@ static void update_countdown_fsm(uint32_t time_ms)
 					sseg_set_char(0, '#', false);
 					sseg_set_char(1, '#', false);
 					sseg_set_char(2, '#', false);
+					buzzer_on(3951);
 					break;
 
 				case 500:
 					sseg_set_char(0, '1', false);
-					buzzer_on(4000);
+					break;
+
+				case 750:
+					buzzer_on(3322);
 					break;
 
 				case 1000:
 					sseg_set_char(0, ' ', false);
-					buzzer_on(2828);
+					buzzer_on(2960);
 					break;
 
 				case 1500:
 					sseg_set_char(1, '1', false);
-					buzzer_on(2000);
+					buzzer_on(2637);
 					break;
 
 				case 2000:
 					sseg_set_char(1, ' ', false);
-					buzzer_on(1414);
+					buzzer_on(2489);
 					break;
 
 				case 2500:
 					sseg_set_char(2, '1', false);
-					buzzer_on(1000);
+					buzzer_on(2217);
 					break;
 
-				case 700:
+				case 200:
+				case 950:
 				case 1200:
 				case 1700:
 				case 2200: