Setup pins, setup timer, shrink code size (static declarations), test

This commit sets up all the appropriate I/O for the AVR as well as
declaring some functions static so GCC will inline them.  In addition,
it provides a simple test function to see if the USB HID reports are
being sent correctly - every 60 reports, it adds one to the report that
it returns, which should result in a binary "counting" appearance in a
gamepad state viewer.

diff --git a/main.c b/main.c
index aee88a4680165f62a8f4dd2645d3660734e26a59..bf3f5e414531c415c694e4ed2e747c9fa57a1ce0 100644 (file)
--- a/main.c
+++ b/main.c
@@ -62,7 +62,20 @@ ISR(TIMER1_COMPA_vect) {
        buttonState.buttons = pollSnes();
 }
 
-void initTimer() {
+static void initPins() {
+       // Enable PD3 as output high (pull-up to D-)
+       DDRD |= _BV(PIND3);
+       PORTD |= _BV(PIND3);
+
+       // Enable PC1:0 as output, and set data clock high
+       // Serial data is PC2 (input, hi-z)
+       // Data latch is PC1 (output, default LOW)
+       // Data clock is PC0 (output, default HIGH)
+       DDRC |= _BV(PINC1) | _BV(PINC0);
+       PORTC |= _BV(PINC0);
+}
+
+static void initTimer() {
        // See section 15.11 for reference
        // Using CTC mode (non-PWM)
 
@@ -84,6 +97,7 @@ int main(void)
 {
        uchar i;
        wdt_enable(WDTO_1S); // Enable watchdog with 1s reset time
+
        /* Even if you don't use the watchdog, turn it off here. On newer devices,
         * the status of the watchdog (on/off, period) is PRESERVED OVER RESET!
         */
@@ -95,14 +109,17 @@ int main(void)
         * additional hardware initialization on the USB side.
         */
        
-       // We need to setup the pin configuration for D3, which is an output pin 
-       
+       // We need to set up the pin configuration for D3 and everything on the SNES side
+       initPins();
 
        // Set up the clock prescaler to CLKI_O/8, which gives us 2250000 ticks per second
        // This makes 37500 such ticks give us a 60Hz signal, which is exactly how we set up
        // the timer interrupt to poll the SNES controller
-       
+       initTimer();
 
+       // Start with no buttons pressed
+       buttonState.buttons = 0;
+       reportBuffer.buttons = 0;
 
        //odDebugInit();
        
@@ -116,14 +133,23 @@ int main(void)
        usbDeviceConnect();
        sei(); // Enable interrupts
        //DBG1(0x01, 0, 0);       /* debug output: main loop starts */
+
+       uchar counter = 0;
+
        for(;;){                /* main event loop */
                //DBG1(0x02, 0, 0);   /* debug output: main loop iterates */
                wdt_reset();
                usbPoll();
                if(usbInterruptIsReady()){
-                       reportBuffer.buttons = buttonState.buttons;
                        /* called after every poll of the interrupt endpoint */
-                       //advanceCircleByFixedAngle();
+                       // Actual code to be executed - updates the HID report with the status of the SNES controller
+                       //reportBuffer.buttons = buttonState.buttons;
+
+                       // Testing USB reports - change button state every second, incrementing the report buffer by 1.
+                       if(counter++ == 60) {
+                               reportBuffer.buttons++;
+                               counter = 0;
+                       }
                        //DBG1(0x03, 0, 0);   /* debug output: interrupt report prepared */
                        usbSetInterrupt((void *)&reportBuffer, sizeof(reportBuffer));
                }