raphaelschaad · November 18, 2015 10:00 · Nov 18, 2015 · Nov 18, 2015 · Nov 17, 2015
diff --git a/att45_schaad1.c b/att45_schaad1.c
@@ -44,10 +44,10 @@ int main() {
    set(PORTB, BTN3);
 
    // PWM to slow motor down
-   static const double kPWMOnDuration = 1.0; // in ms
-   static const double kPWMSleepDuration = 20.0; // in ms
-   static bool motorCWOn = false;
-   static bool motorCCWOn = false;
+   const double kPWMOnDuration = 1.0; // in ms
+   const double kPWMSleepDuration = 10.0; // in ms
+   bool motorCWOn = false;
+   bool motorCCWOn = false;
 
    // Spin event loop
    while (true) {
@@ -79,9 +79,18 @@ int main() {
          motorCWOn = false;
          // Clear immediately because of following delay stalling the event loop.
          clear(PORTB, MOTORCW);
+         // Lift flag off the right button by turning motor back CCW just a bit.
+         const unsigned int kCount = 30;
+         unsigned int i;
+         for (i = 0; i < kCount; ++i) {
+            set(PORTB, MOTORCCW);
+            _delay_ms(kPWMOnDuration);
+            clear(PORTB, MOTORCCW);
+            _delay_ms(kPWMSleepDuration);
+         }
 
-         // Wait for 8 seconds, and turn motor back CCW.
-         _delay_ms(8000.0);
+         // Wait for 7 seconds, and turn motor back CCW.
+         _delay_ms(7000.0);
          motorCCWOn = true;
       }
 

diff --git a/att45_schaad1.c b/att45_schaad1.c
@@ -44,8 +44,8 @@ int main() {
    set(PORTB, BTN3);
 
    // PWM to slow motor down
-   static const double kPWMOnDuration = 1.0; // in centiseconds
-   static const double kPWMSleepDuration = 20.0; // in centiseconds
+   static const double kPWMOnDuration = 1.0; // in ms
+   static const double kPWMSleepDuration = 20.0; // in ms
    static bool motorCWOn = false;
    static bool motorCCWOn = false;
 
@@ -81,7 +81,7 @@ int main() {
          clear(PORTB, MOTORCW);
 
          // Wait for 8 seconds, and turn motor back CCW.
-         _delay_ms(800.0);
+         _delay_ms(8000.0);
          motorCCWOn = true;
       }
 

diff --git a/att45_schaad1.make b/att45_schaad1.make
@@ -8,9 +8,8 @@
 PROJECT=att45_schaad1
 SOURCES=$(PROJECT).c
 MMCU=attiny45
-F_CPU = 8000000
 
-CFLAGS=-mmcu=$(MMCU) -Wall -Os -DF_CPU=$(F_CPU)
+CFLAGS=-mmcu=$(MMCU) -Wall -Os
 
 $(PROJECT).hex: $(PROJECT).out
 	avr-objcopy -O ihex $(PROJECT).out $(PROJECT).c.hex;\

diff --git a/att45_schaad1.c b/att45_schaad1.c
@@ -0,0 +1,96 @@
+//
+//  att45_schaad1.c
+//
+//  Created by Raphael Schaad on 2015-11-16.
+//  This is free and unencumbered software released into the public domain.
+//
+
+// Import headers installed with CrossPack-AVR (/usr/local/CrossPack-AVR/)
+#include "stdbool.h" // So we have 'true' and 'false' instead of 1 and 0 (might have memory implications) -- lib/gcc/avr/4.8.1/include/
+#include <avr/io.h> // Umbrella header including e.g. iotn45.h for our chip, defining PORTB/DDRB/PBn -- avr/include/avr/
+#include <util/delay.h> // _delay_us/ms convenience functions for actual time values rather than number of cycles -- avr/include/util
+
+// Hardware:
+// Based on Neil Gershenfeld's board: http://academy.cba.mit.edu/classes/output_devices/H-bridge/hello.H-bridge.44.png
+// With my redesign and enhancements: http://fab.cba.mit.edu/classes/863.15/section.CBA/people/Schaad/week9-output-devices.html
+#define BTN1     (1 << PB2) // left   (pin 7)
+#define BTN2     (1 << PB3) // center (pin 2)
+#define BTN3     (1 << PB4) // right  (pin 3)
+#define MOTORCCW (1 << PB0) // IN1    (pin 5)
+#define MOTORCW  (1 << PB1) // IN2    (pin 6)
+
+// Convenience macros
+#define output(directions, pin) (directions |= pin)    // set port direction for output
+#define input(directions, pin)  (directions &= (~pin)) // set port direction for input
+#define set(port, pin)          (port |= pin)          // set port pin
+#define clear(port, pin)        (port &= (~pin))       // clear port pin
+#define pin_test(pins, pin)     (pins & pin)           // test for port pin
+#define bit_test(byte, bit)     (byte & (1 << bit))    // test for bit set
+
+// Bootloader calls main(void) when the chip gets power
+int main() {
+   // Configure digital I/O pins DDRB (bits are 0-based index)
+   output(DDRB, MOTORCCW);
+   output(DDRB, MOTORCW);
+
+   // For input, also turn on pullup resistors with set(PORTB, BTNn)
+   input(DDRB, BTN1);
+   set(PORTB, BTN1);
+
+   input(DDRB, BTN2);
+   set(PORTB, BTN2);
+
+   input(DDRB, BTN3);
+   set(PORTB, BTN3);
+
+   // PWM to slow motor down
+   static const double kPWMOnDuration = 1.0; // in centiseconds
+   static const double kPWMSleepDuration = 20.0; // in centiseconds
+   static bool motorCWOn = false;
+   static bool motorCCWOn = false;
+
+   // Spin event loop
+   while (true) {
+      if (motorCWOn) {
+         set(PORTB, MOTORCW);
+         _delay_ms(kPWMOnDuration);
+         clear(PORTB, MOTORCW);
+         _delay_ms(kPWMSleepDuration);
+      } else {
+         clear(PORTB, MOTORCW);
+      }
+
+      if (motorCCWOn) {
+         set(PORTB, MOTORCCW);
+         _delay_ms(kPWMOnDuration);
+         clear(PORTB, MOTORCCW);
+         _delay_ms(kPWMSleepDuration);
+      } else {
+         clear(PORTB, MOTORCCW);
+      }
+
+      // Once center button is pressed, turn motor CW.
+      if (!pin_test(PINB, BTN2)) {
+         motorCWOn = true;
+      }
+
+      // Once right button is hit, turn motor off.
+      if (!pin_test(PINB, BTN3)) {
+         motorCWOn = false;
+         // Clear immediately because of following delay stalling the event loop.
+         clear(PORTB, MOTORCW);
+
+         // Wait for 8 seconds, and turn motor back CCW.
+         _delay_ms(800.0);
+         motorCCWOn = true;
+      }
+
+      // Once left button is hit, turn motor off.
+      if (!pin_test(PINB, BTN1)) {
+         motorCCWOn = false;
+      }
+   }
+
+   // When main(void) exits, the chip goes idle
+   return 0;
+}
diff --git a/att45_schaad1.make b/att45_schaad1.make
@@ -0,0 +1,23 @@
+#
+#  att45_schaad1.make
+#
+#  Created by Raphael Schaad on 2015-11-16.
+#  This is free and unencumbered software released into the public domain.
+#
+
+PROJECT=att45_schaad1
+SOURCES=$(PROJECT).c
+MMCU=attiny45
+F_CPU = 8000000
+
+CFLAGS=-mmcu=$(MMCU) -Wall -Os -DF_CPU=$(F_CPU)
+
+$(PROJECT).hex: $(PROJECT).out
+	avr-objcopy -O ihex $(PROJECT).out $(PROJECT).c.hex;\
+	avr-size --mcu=$(MMCU) --format=avr $(PROJECT).out
+
+$(PROJECT).out: $(SOURCES)
+	avr-gcc $(CFLAGS) -I./ -o $(PROJECT).out $(SOURCES)
+
+program-usbtiny: $(PROJECT).hex
+	avrdude -p t45 -P usb -c usbtiny -U flash:w:$(PROJECT).c.hex
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