Speaker

src/hmi.c

@@ -110,6 +110,28 @@ void blink_collision(void)
 	led_right_off();
 }
 
+/**
+ * @brief Warn low battery using speaker sounds.
+ */
+void speaker_warn_low_battery(void)
+{
+	speaker_play('C', 4, 0, 0.05);
+	sleep_ticks(50);
+	speaker_play('C', 3, 0, 0.05);
+	sleep_ticks(50);
+}
+
+/**
+ * @brief Play three fast, high tones to note a successful operation.
+ */
+void speaker_play_success(void)
+{
+	for (int i = 0; i < 3; i++) {
+		speaker_play('C', 8, 0, 0.05);
+		sleep_ticks(50);
+	}
+}
+
 /**
  * @brief Function to read button left.
  */

src/hmi.h

@@ -5,6 +5,7 @@
 
 #include "clock.h"
 #include "detection.h"
+#include "speaker.h"
 #include "speed.h"
 
 void led_left_toggle(void);
@@ -18,6 +19,8 @@ void led_right_off(void);
 void led_bluepill_off(void);
 void repeat_blink(uint8_t count, uint16_t time);
 void blink_collision(void);
+void speaker_warn_low_battery(void);
+void speaker_play_success(void);
 bool button_left_read(void);
 bool button_right_read(void);
 bool button_left_read_consecutive(uint32_t count);

src/main.c

@@ -12,6 +12,7 @@
 #include "serial.h"
 #include "setup.h"
 #include "solve.h"
+#include "speaker.h"
 #include "speed.h"
 
 static void competition(void);
@@ -46,6 +47,24 @@ static void user_configuration(bool run)
 	set_speed_mode(mode, run);
 }
 
+/**
+ * @brief Check battery voltage and warn if the voltage is getting too low.
+ */
+static void check_battery_voltage(void)
+{
+	float voltage;
+
+	voltage = get_battery_voltage();
+	if (voltage < 3.6)
+		speaker_warn_low_battery();
+	if (voltage < 3.5)
+		speaker_warn_low_battery();
+	if (voltage < 3.4)
+		speaker_warn_low_battery();
+	if (voltage < 3.3)
+		speaker_play('C', 3, 0, 2.);
+}
+
 /**
  * @brief Includes the functions to be executed before robot starts to move.
  */
@@ -55,6 +74,7 @@ static void before_moving(void)
 	disable_walls_control();
 	repeat_blink(10, 100);
 	sleep_us(5000000);
+	check_battery_voltage();
 	led_left_on();
 	led_right_on();
 	wait_front_sensor_close_signal(0.12);
@@ -75,9 +95,11 @@ static void after_moving(void)
 		reset_motion();
 		blink_collision();
 	} else {
+		speaker_play_success();
 		repeat_blink(10, 100);
 	}
 	reset_motion();
+	check_battery_voltage();
 }
 
 /**

src/setup.c

@@ -63,11 +63,9 @@ static void setup_clock(void)
  *
  * - Systick priority to 1 with SCB.
  * - USART3 with priority 2 with NVIC.
- * - TIM1_UP with priority 0.
  *
  * Interruptions enabled:
  *
- * - TIM1 Update interrupt.
  * - USART3 interrupt.
  *
  * @note The priority levels are assigned on steps of 16 because the processor
@@ -77,11 +75,9 @@ static void setup_clock(void)
  */
 static void setup_exceptions(void)
 {
-	nvic_set_priority(NVIC_TIM1_UP_IRQ, 0);
 	nvic_set_priority(NVIC_SYSTICK_IRQ, PRIORITY_FACTOR * 1);
 	nvic_set_priority(NVIC_USART3_IRQ, PRIORITY_FACTOR * 2);
 
-	nvic_enable_irq(NVIC_TIM1_UP_IRQ);
 	nvic_enable_irq(NVIC_USART3_IRQ);
 }
 
@@ -218,7 +214,7 @@ void setup_spi_low_speed(void)
  * @see Reference manual (RM0008) "TIMx functional description" and in
  * particular "PWM mode" section.
  */
-static void setup_pwm(void)
+static void setup_motor_driver(void)
 {
 	timer_set_mode(TIM3, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE,
 		       TIM_CR1_DIR_UP);
@@ -252,6 +248,44 @@ static void setup_pwm(void)
 	timer_enable_counter(TIM3);
 }
 
+/**
+ * @brief Setup PWM for the speaker.
+ *
+ * TIM1 is used to generate the PWM signals for the speaker:
+ *
+ * - Configure channel 3 as output GPIO.
+ * - Edge-aligned, up-counting timer.
+ * - Prescale to increment timer counter at TIM1CLK_FREQUENCY_HZ.
+ * - Set output compare mode to PWM1 (output is active when the counter is
+ *   less than the compare register contents and inactive otherwise.
+ * - Disable output compare output (speaker is off by default).
+ * - Enable outputs in the break subsystem.
+ *
+ * @see Reference manual (RM0008) "TIMx functional description" and in
+ * particular "PWM mode" section.
+ */
+static void setup_speaker(void)
+{
+	gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
+		      GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_TIM1_CH3);
+
+	rcc_periph_reset_pulse(RST_TIM1);
+
+	timer_set_mode(TIM1, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE,
+		       TIM_CR1_DIR_UP);
+
+	timer_set_prescaler(TIM1,
+			    (rcc_apb2_frequency / TIM1CLK_FREQUENCY_HZ - 1));
+	timer_set_repetition_counter(TIM1, 0);
+	timer_enable_preload(TIM1);
+	timer_continuous_mode(TIM1);
+
+	timer_disable_oc_output(TIM1, TIM_OC3);
+	timer_set_oc_mode(TIM1, TIM_OC3, TIM_OCM_PWM1);
+
+	timer_enable_break_main_output(TIM1);
+}
+
 /**
  * @brief Configure timer to read a quadrature encoder.
  *
@@ -406,40 +440,6 @@ static void setup_adc2(void)
 	start_adc(ADC2);
 }
 
-/**
- * @brief TIM1 setup.
- *
- * The TIM1 generates an update event interruption that invokes the
- * function tim1_up_isr.
- *
- * - Set TIM1 default values.
- * - Configure the base time (no clock division ratio, no aligned mode,
- *   direction up).
- * - Set clock division, prescaler and period parameters to get an update
- *   event with a frequency of 16 KHz. 16 interruptions by ms, 4 sensors with
- *   4 states.
- *
- *   \f$frequency = \frac{timerclock}{(preescaler + 1)(period + 1)}\f$
- *
- * - Enable the TIM1.
- * - Enable the interruption of type update event on the TIM1.
- *
- * @note The TIM1 is conected to the APB2 prescaler.
- *
- * @see Reference manual (RM0008) "Advanced-control timers"
- */
-static void setup_timer1(void)
-{
-	rcc_periph_reset_pulse(RST_TIM1);
-	timer_set_mode(TIM1, TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE,
-		       TIM_CR1_DIR_UP);
-	timer_set_clock_division(TIM1, 0x00);
-	timer_set_prescaler(TIM1, (rcc_apb2_frequency / 160000 - 1));
-	timer_set_period(TIM1, 10 - 1);
-	timer_enable_counter(TIM1);
-	timer_enable_irq(TIM1, TIM_DIER_UIE);
-}
-
 /**
  * @brief Execute all setup functions.
  */
@@ -452,9 +452,8 @@ void setup(void)
 	setup_adc2();
 	setup_usart();
 	setup_encoders();
-	setup_pwm();
+	setup_motor_driver();
+	setup_speaker();
 	setup_mpu();
 	setup_systick();
-	setup_timer1();
-	setup_adc1();
 }

src/setup.h

@@ -26,6 +26,7 @@
 
 /** System clock frequency is set in `setup_clock` */
 #define SYSCLK_FREQUENCY_HZ 72000000
+#define TIM1CLK_FREQUENCY_HZ 1000000
 #define SYSTICK_FREQUENCY_HZ 1000
 #define DRIVER_PWM_PERIOD 1024
 

src/speaker.c

@@ -0,0 +1,66 @@
+#include "speaker.h"
+
+uint8_t BASE_NOTE = 9;
+uint8_t BASE_OCTAVE = 4;
+float BASE_FREQUENCY = 440.;
+uint8_t POSITIONS[8] = {9, 11, 0, 2, 4, 5, 7};
+
+/**
+ * @brief Set the frequency for the speaker.
+ *
+ * Frequency is set modulating the PWM signal sent to the speaker.
+ *
+ * @param[in] hz Frequency, in Hertz.
+ */
+static void speaker_set_frequency(float hz)
+{
+	uint16_t period;
+
+	period = (uint16_t)(TIM1CLK_FREQUENCY_HZ / hz);
+	timer_set_period(TIM1, period);
+	timer_set_oc_value(TIM1, TIM_OC3, period / 2);
+}
+
+/**
+ * @brief Turn on the speaker to play the set frequency.
+ */
+static void speaker_on(void)
+{
+	timer_enable_counter(TIM1);
+	timer_enable_oc_output(TIM1, TIM_OC3);
+}
+
+/**
+ * @brief Turn off the speaker.
+ */
+static void speaker_off(void)
+{
+	timer_disable_counter(TIM1);
+	timer_disable_oc_output(TIM1, TIM_OC3);
+}
+
+/**
+ * @brief Play a note through the speaker.
+ *
+ * Even if this function uses the scientific notation, notes are played with
+ * the concert pitch (standard pitch). That means A above middle C is the
+ * reference note, played at 440 Hz.
+ *
+ * @param[in] note Which note to play, in scientific notation.
+ * @param[in] octave Which octave to play, in scientific notation.
+ * @param[in] accidental Number of semitones to sum to the note.
+ * @param[in] duration Duration of the note, in seconds.
+ */
+void speaker_play(char note, uint8_t octave, int8_t accidental, float duration)
+{
+	int16_t sound;
+	float frequency;
+
+	sound = POSITIONS[note - 'A'] - BASE_NOTE + (octave - BASE_OCTAVE) * 12;
+	sound += accidental;
+	frequency = pow(2, sound / 12.) * BASE_FREQUENCY;
+	speaker_set_frequency(frequency);
+	speaker_on();
+	sleep_ticks((uint32_t)(duration * 1000));
+	speaker_off();
+}

src/speaker.h

@@ -0,0 +1,12 @@
+#ifndef __SPEAKER_H
+#define __SPEAKER_H
+
+#include <math.h>
+
+#include <libopencm3/stm32/timer.h>
+
+#include "setup.h"
+
+void speaker_play(char note, uint8_t octave, int8_t accidental, float duration);
+
+#endif /* __SPEAKER_H */