Use timer interrupt for button state

- Move Timer2 setup into btn_init()
- Move button polling and debouncing internal to btn.c
- Function pointer btn_report_gesture

bekantfirmware.X/bekant/bui.c

@@ -4,6 +4,7 @@
 
 #include "bui.h"
 #include "bctrl.h"
+#include <stdlib.h> // abs()
 
 typedef enum {
     BUI_STOP,

bekantfirmware.X/btn/btn.c

@@ -1,9 +1,21 @@
 
 
 #include "btn.h"
-
+#include <pic.h>
+#include <stdbool.h>       /* For true/false definition */
 #include <stdint.h>        /* For uint8_t definition */
 
+// A mapping to PORTB
+// Determined by PCB traces
+typedef union {
+    PORTBbits_t PORTB;
+    struct {
+        unsigned DOWN : 1;
+        unsigned UP : 1;
+        unsigned : 6;
+    };
+} ButtonState_t;
+
 #define PRESSED(b) (!b)
 #define RELEASED(b) (b)
 #define BUTTON_CHANGE(a, b) ((a.UP != b.UP) || (a.DOWN != b.DOWN))
@@ -43,6 +55,8 @@ bool btn_debounce(ButtonState_t now_btn) {
     }
 }
 
+bool btn_debounce(ButtonState_t now_btn);
+
 typedef struct {
     uint8_t save_hold;
     INPUT_t state;
@@ -137,3 +151,36 @@ INPUT_t btn_gesture(ButtonState_t btn) {
 
     return input.state;
 }
+
+void (*btn_report_gesture)(INPUT_t gesture);
+
+void btn_timer() {
+    static INPUT_t last_input = INPUT_IDLE;
+
+    ButtonState_t button_state = (ButtonState_t)PORTBbits;
+
+    if (btn_debounce(button_state)) {
+        INPUT_t input = btn_gesture(button_state);
+
+        if (input != last_input) {
+            last_input = input;
+
+            btn_report_gesture(input);
+        }
+    }
+}
+
+void btn_init(void) {
+    // Timer2 clock input is Fosc/4 (instruction clock)
+    // System Fosc: 16 Mhz
+    // Instruction clock: Fosc / 4 = 4 Mhz
+    // 4 Mhz / 100 period / 10 postscaler = 4000 Hz
+    //   0.00025 sec
+    //   250 usec
+    T2CONbits.T2CKPS = 0b00; // Prescaler is 1
+    PR2bits.PR2 = 100; // Timer2 period
+    T2CONbits.T2OUTPS = 0b1001; // 1:10 Postscaler
+
+    T2CONbits.TMR2ON = 1; // Timer is on
+    PIE1bits.TMR2IE = 1; // Enable Timer2 interrupt
+}

bekantfirmware.X/btn/btn.h

@@ -1,23 +1,7 @@
 
-#include <pic.h>
-#include <stdbool.h>       /* For true/false definition */
-
 #ifndef BTN_H
 #define BTN_H
 
-// A mapping to PORTB
-// Determined by PCB traces
-typedef union {
-    PORTBbits_t PORTB;
-    struct {
-        unsigned DOWN : 1;
-        unsigned UP : 1;
-        unsigned : 6;
-    };
-} ButtonState_t;
-
-bool btn_debounce(ButtonState_t now_btn);
-
 typedef enum {
     INPUT_IDLE,
     INPUT_UP,
@@ -27,6 +11,8 @@ typedef enum {
     INPUT_SAVE,
 } INPUT_t;
 
-INPUT_t btn_gesture(ButtonState_t btn);
+void btn_init(void);
+void btn_timer(void);
+extern void (*btn_report_gesture)(INPUT_t gesture);
 
 #endif /* BTN_H */

bekantfirmware.X/interrupts.c

@@ -5,6 +5,7 @@
 
 #include "lin/lin_d.h"
 #include "bekant/bctrl.h"
+#include "btn/btn.h"
 
 void __interrupt() isr(void)
 {
@@ -14,5 +15,8 @@ void __interrupt() isr(void)
     } else if (PIR3bits.TMR4IF) {
         bctrl_timer();
         PIR3bits.TMR4IF = false;
+    } else if (PIR1bits.TMR2IF) {
+        btn_timer();
+        PIR1bits.TMR2IF = false;
     }
 }

bekantfirmware.X/main.c

@@ -25,7 +25,6 @@ void main(void) {
 
     ANSELB = 0b00000000;
     TRISB = 0b00000011;
-    INPUT_t last_input = INPUT_IDLE;
 
     LATC = 1;  // Enables LIN input to echo back from the bus
     TRISC = 0b10000000; // C7: input (serial RX)
@@ -38,6 +37,8 @@ void main(void) {
     bctrl_init();
 
     bui_init();
+
+    btn_init();
 
     // TEST CODE TO DEBUG IN SIMULATOR
     //lin_id = 0x11;
@@ -49,20 +50,6 @@ void main(void) {
     //lin_tx_frame();
 
     while (1) {
-        ButtonState_t button_state = (ButtonState_t)PORTBbits;
-
-        if (btn_debounce(button_state)) {
-            INPUT_t input = btn_gesture(button_state);
-
-            if (input != last_input) {
-                last_input = input;
-
-                bui_input(input);
-            }
-        }
-
         CLRWDT();
-        while (!PIR1bits.TMR2IF);
-        PIR1bits.TMR2IF = false;
     }
 }

bekantfirmware.X/system.c

@@ -22,16 +22,4 @@ void ConfigureOscillator(void)
     OPTION_REGbits.TMR0SE = 1; // TMR0SE Increment on high-to-low transition on T0CKI pin
     OPTION_REGbits.PSA = 0; // PSA Prescaler is assigned to the Timer0 module
     OPTION_REGbits.PS = 0b010; // 010 Prescaler 1:8
-
-    // Timer2 clock input is Fosc/4 (instruction clock)
-    // System Fosc: 16 Mhz
-    // Instruction clock: Fosc / 4 = 4 Mhz
-    // 4 Mhz / 100 period / 10 postscaler = 4000 Hz
-    //   0.00025 sec
-    //   250 usec
-    PR2bits.PR2 = 100; // Timer2 period
-
-    T2CONbits.T2OUTPS = 0b1001; // 1:10 Postscaler
-    T2CONbits.T2CKPS = 0b00; // Prescaler is 1
-    T2CONbits.TMR2ON = 1; // Timer is on
 }

bekantfirmware.X/user.c

@@ -15,6 +15,7 @@
 #include "lin/lin_d.h"
 #include "bekant/bctrl.h"
 #include "bekant/bui.h"
+#include "btn/btn.h"
 
 /******************************************************************************/
 /* User Functions                                                             */
@@ -29,6 +30,8 @@ void InitApp(void)
     lin_frame_finish = bctrl_rx_lin;
     // hook up BEKANT control module to BEKANT UI module
     bctrl_report_pos = bui_set_pos;
+    // Pass button gesture to BEKANT UI input
+    btn_report_gesture = bui_input;
 
     /* TODO Initialize User Ports/Peripherals/Project here */