ADC Functionality

include/ADC.h

@@ -0,0 +1,24 @@
+// ADC Class Header
+#ifndef ADC_H
+#define ADC_H
+
+#include <kinetis.h>
+#include "PDB.h"
+
+#define ADC_MAX_12B     (1 << 12)
+#define ADC_REF         3.3
+
+class ADC
+{
+private:
+    PDB m_pdb;
+
+public:
+    ADC (uint16_t sample_rate);
+
+    uint8_t     calibrate (void);
+    void        start (void);
+    uint16_t    get_latest_sample (void);
+};
+
+#endif // ADC_H

include/PDB.h

@@ -0,0 +1,15 @@
+// PDB (Programmable Delay Block) Class Header
+#ifndef PDB_H
+#define PDB_H
+
+#include <kinetis.h>
+
+class PDB
+{
+public:
+    PDB (uint16_t timer_freq);
+
+    void start (void);
+};
+
+#endif // PDB_H

src/ADC.cpp

@@ -0,0 +1,82 @@
+#include <core_pins.h>
+#include "ADC.h"
+
+#define NUM_ADC_MODULES         2
+#define MAX_NUM_ADC_CHANNELS    24
+
+#define PDB_TRIG                0x0     // SIM_SOPT7 PDB Trigger
+#define PIT_TRIG0               0x4     // SIM_SOPT7 PIT Trigger
+
+static uint16_t s_adc_0_sample = 0;
+
+// ADC ISR
+void adc0_isr(void)
+{
+    // Only update sample value if Conversion Complete flag is set
+    if (ADC0_SC1A & ADC_SC1_COCO) 
+    {
+        s_adc_0_sample = ADC0_RA;
+    }
+}
+
+ADC::ADC (uint16_t sample_rate)
+    : m_pdb (sample_rate)
+{
+    SIM_SCGC6  |= SIM_SCGC6_ADC0;       // Enable CLK to ADC0
+
+    ADC0_CFG1   = ADC_CFG1_ADLSMP       // Long Sample Time
+                | ADC_CFG1_ADIV(0)      // Clock div = 1
+                | ADC_CFG1_MODE(1)      // 12-bit mode
+                | ADC_CFG1_ADICLK(0);   // Select bus clock
+
+    ADC0_CFG2   = ADC_CFG2_ADLSTS(1);   // Set sample time to 12 samples
+                                        // MUX_SEL = 0; Channel A selected
+
+    ADC0_SC2    = ADC_SC2_ADTRG         // Hardware trigger
+                | ADC_SC2_REFSEL(0);    // Select reference = VREFH, VREFL
+
+    ADC0_SC3    = ADC_SC3_AVGE          // Hardware average enable
+                | ADC_SC3_AVGS(0);      // Averages 4 samples
+
+    ADC0_SC1A   = ADC_SC1_AIEN          // Conversion complete interrupt enable
+                | ADC_SC1_ADCH(0x0F);   // Input PC1 (A8 on Teensy 3.2)
+
+    SIM_SOPT7  &= ~(SIM_SOPT7_ADC0ALTTRGEN              // ADC0 trigger
+                |   SIM_SOPT7_ADC0TRGSEL(PDB_TRIG));    // Set PDB to trigger ADC0
+
+    // Enable ADC ISR
+    NVIC_ENABLE_IRQ(IRQ_ADC0);
+}
+
+// Perform ADC calibration
+uint8_t ADC::calibrate (void) 
+{
+    uint8_t err;
+
+    ADC0_SC3 |= ADC_SC3_CAL;      // Begin ADC Calibration
+
+    while (ADC0_SC3 & ADC_SC3_CAL)
+        ;  // Wait for calibration to complete
+
+    // Check for calibration error
+    err = ((ADC0_SC3 & ADC_SC3_CALF) != 0) ? 1 : 0;
+    return err;
+}
+
+void ADC::start (void)
+{
+    m_pdb.start();
+}
+
+// Returns the latest computed ADC sample
+uint16_t ADC::get_latest_sample (void) 
+{
+    // static uint16_t sample = 0;
+
+    // // Only update sample value if Conversion Complete flag is set
+    // if (ADC0_SC1A & ADC_SC1_COCO) 
+    // {
+    //     sample = ADC0_RA;
+    // }
+    return s_adc_0_sample;
+}

src/PDB.cpp

@@ -0,0 +1,41 @@
+#include "PDB.h"
+
+#define PDB_CHxCx_TOS(n)    (1 << (n + 8))
+#define PDB_CHxCx_EN(n)     (1 << (n))
+
+// PDB ISR
+void pdb_isr (void) 
+{
+    PDB0_SC &= ~PDB_SC_PDBIF;    // Clear PDB Int flag
+}
+
+PDB::PDB (uint16_t timer_freq)
+{
+    SIM_SCGC6  |= SIM_SCGC6_PDB;        // Enable CLK to PDB
+
+    PDB0_SC     = PDB_SC_PDBEN          // PDB Enable
+                | PDB_SC_PDBIE          // PDB Int Enable
+                | PDB_SC_MULT(0)        // MULT = 1x
+                | PDB_SC_PRESCALER(0)   // Prescaler = 2^0
+                | PDB_SC_CONT           // Continuous Mode
+                | PDB_SC_TRGSEL(0xF);   // Select Software Trigger
+    // Config other PDB Registers
+    PDB0_IDLY   = 0;                    // Trigger Int every counter reset
+
+    PDB0_CH0C1  |= PDB_CHxCx_TOS(0)     // PDB0 Pre-Trigger Output
+                |  PDB_CHxCx_EN(0);     // PDB0 Pre-Trigger Enable
+
+    //PDB0_CH0DLY0 = 0x0000;
+
+    PDB0_MOD    = (F_BUS / timer_freq) - 1; // Set Timer value to trigger @ timer_freq
+
+    PDB0_SC     |= PDB_SC_LDOK;        // Load new config to PDB registers
+
+    // Enable PDB ISR
+    NVIC_ENABLE_IRQ (IRQ_PDB);
+}
+
+void PDB::start (void) 
+{
+    PDB0_SC |= PDB_SC_SWTRIG;  // Starts the PDB and its trigger
+}

src/main.cpp

@@ -3,18 +3,31 @@
 #include "GPIO.h"
 #include "Encoder.h"
 #include "SoftwareTimer.h"
+#include "ADC.h"
 
 #define NUM_LEDS        5
-#define NUM_BTNS        3
-#define LOOP_PERIOD_MS  100
+// #define NUM_BTNS        3
+#define LOOP_PERIOD_MS  10
 #define LED_FREQ_HZ     4
-#define PRINT_LOOP_CNT  5
+#define PRINT_LOOP_CNT  50
 #define BPM_DIV         30
 
+#define ADC_SAMPLE_RATE 1000
 #define SERIAL_SPEED    9600
 #define PRINT_BUF_SIZE  64
 
 void led_timer_cb (void);
+static void handle_switch_input (void);
+static void handle_button_input (void);
+static void handle_encoder_input (uint16_t * encoder_count);
+
+enum btn_id_t
+{
+    BTN_ID_LEFT,
+    BTN_ID_CENTER,
+    BTN_ID_RIGHT,
+    NUM_BTN_IDS
+};
 
 GPIO leds [NUM_LEDS] =
 {
@@ -25,17 +38,18 @@ GPIO leds [NUM_LEDS] =
     GPIO (DIR_OUTPUT, GPIO_PIN_13),
 };
 
-GPIO btns [NUM_BTNS] =
+GPIO btns [NUM_BTN_IDS] =
 {
     GPIO (DIR_INPUT, GPIO_PIN_4),
     GPIO (DIR_INPUT, GPIO_PIN_5),
     GPIO (DIR_INPUT, GPIO_PIN_6),
 };
 
-GPIO    enable_sw   = GPIO (DIR_INPUT, GPIO_PIN_11);
-GPIO    debug_gpio  = GPIO (DIR_OUTPUT, DEBUG_GPIO_PIN_NUM);
-Encoder encoder     = Encoder (GPIO_PIN_15, GPIO_PIN_14);
-SoftwareTimer * led_tmr = NULL;
+GPIO            enable_sw   = GPIO (DIR_INPUT, GPIO_PIN_11);
+GPIO            debug_gpio  = GPIO (DIR_OUTPUT, DEBUG_GPIO_PIN_NUM);
+Encoder         encoder     = Encoder (GPIO_PIN_15, GPIO_PIN_14);
+ADC             adc         = ADC (ADC_SAMPLE_RATE);
+SoftwareTimer * led_tmr     = NULL;
 
 void led_timer_cb (void)
 {
@@ -47,7 +61,7 @@ void led_timer_cb (void)
     led_state ^= 0x01;
 }
 
-void handle_switch_input (void)
+static void handle_switch_input (void)
 {
     static uint8_t  prev_sw_state   = 0;
     uint8_t         sw_state        = enable_sw.read();
@@ -68,6 +82,68 @@ void handle_switch_input (void)
     prev_sw_state = sw_state;
 }
 
+static void handle_button_input (void)
+{
+    uint8_t         btn_num         = 0;
+    uint8_t         temp_btn_state  = LOW;
+    int8_t          temp_led_num    = 0;
+    uint8_t         min_led_num     = 1;
+    uint8_t         prev_active_led = min_led_num;
+    static uint8_t  active_led_num  = min_led_num;
+    static uint8_t  led_state       = HIGH;
+    static uint8_t  btn_state [NUM_BTN_IDS] = {LOW};
+
+    for (btn_num = 0; btn_num < NUM_BTN_IDS; btn_num++)
+    {
+        temp_btn_state = btns [btn_num].read();
+
+        if ((temp_btn_state == HIGH) && (btn_state [btn_num] == LOW))
+        {
+            prev_active_led = active_led_num;
+
+            if (btn_num == BTN_ID_LEFT && led_state)
+            {
+                // Decrement LED - handle negative modulo
+                temp_led_num    = (active_led_num - min_led_num - 1);
+                temp_led_num    = (temp_led_num < 0) ? (NUM_BTN_IDS - 1) : temp_led_num;
+                active_led_num  = (temp_led_num + min_led_num);
+            }
+            else if (btn_num == BTN_ID_RIGHT && led_state)
+            {
+                // Increment LED
+                temp_led_num    = (active_led_num - min_led_num + 1);
+                active_led_num  = (temp_led_num % NUM_BTN_IDS) + min_led_num;
+            }
+            else if (btn_num == BTN_ID_CENTER)
+            {
+                // Toggle LED state
+                led_state ^= 0x01;
+            }
+
+            // Turn off previous LED
+            leds [prev_active_led].write(0);
+            // Turn on new LED
+            leds [active_led_num].write(led_state);
+        }
+        // Update button state
+        btn_state [btn_num] = temp_btn_state;
+    }
+}
+
+// Update the encoder count, change LED freq accordingly
+static void handle_encoder_input (uint16_t * encoder_count)
+{
+    static uint16_t prev_enc_count  = *encoder_count;
+    *encoder_count = encoder.get_count();
+
+    if (*encoder_count != prev_enc_count)
+    {
+        prev_enc_count = *encoder_count;
+
+        led_tmr->set_freq(*encoder_count * 1.0 / BPM_DIV);
+    }
+}
+
 void setup() 
 {
     // Put your setup code here, to run once:
@@ -77,52 +153,33 @@ void setup()
     GPIO::init();
 
     led_tmr = SoftwareTimer::getTimer (LED_FREQ_HZ, led_timer_cb, true);
+    adc.start();
+
+    Serial.begin(SERIAL_SPEED);
 }
 
 void loop() 
 {
-    // Put your main code here, to run repeatedly:
-    static uint8_t  led_num         = 0;
-    uint8_t         btn_num         = 0;
-    uint8_t         temp_btn_state  = LOW;
+    uint16_t        adc_sample      = 0;
+    float           adc_reading     = 0;
     static uint16_t encoder_count   = encoder.get_count();
-    static uint16_t prev_enc_count  = encoder_count;
     static uint8_t  loop_cnt        = 0;
-    static uint8_t  led_state [NUM_LEDS] = {LOW};
-    static uint8_t  btn_state [NUM_BTNS] = {LOW};
-
-    for (btn_num = 0; btn_num < NUM_BTNS; btn_num++)
-    {
-        temp_btn_state = btns [btn_num].read();
-
-        if ((temp_btn_state == HIGH) && (btn_state [btn_num] == LOW))
-        {
-            // Toggle the LED whenever its button is high
-            led_num = btn_num + 1;
-            led_state [led_num] ^= 0x01;
-            leds [led_num].write(led_state [led_num]);
-        }
-        // Update button state
-        btn_state [btn_num] = temp_btn_state;
-    }
+
+    handle_button_input();
 
     handle_switch_input();
 
-    // Update the encoder count, change LED freq accordingly
-    encoder_count = encoder.get_count();
-
-    if (encoder_count != prev_enc_count)
-    {
-        prev_enc_count = encoder_count;
-
-        led_tmr->set_freq(encoder_count * 1.0 / BPM_DIV);
-    }
+    handle_encoder_input(&encoder_count);
 
     if (loop_cnt == PRINT_LOOP_CNT)
     {
         loop_cnt = 0;
 
+        adc_sample  = adc.get_latest_sample();
+        adc_reading = (adc_sample * ADC_REF) / ADC_MAX_12B;
+
         Serial.printf ("Encoder: %u\n", encoder_count);
+        Serial.printf ("ADC Sample: %2.3fV\n", adc_reading);
     }
 
     loop_cnt++;