usb-relay/src/main.c

#include <util/delay.h>
#include <avr/io.h>
#include <avr/pgmspace.h>

#include <LUFA/Drivers/USB/USB.h>

#include "Descriptors.h"

// Pro Micro LEDs are: B0, D5

#define LED_SETUP()		DDRB |= (1<<0); DDRD |= (1<<5);
#define L_LED_OFF()		PORTD |= (1<<5)
#define L_LED_ON()		PORTD &= ~(1<<5)
#define DATA_LED_OFF()	PORTB |= (1<<0)
#define DATA_LED_ON()	PORTB &= ~(1<<0)

static uint16_t DataBlinkCounter = 0;
static uint32_t HeartbeatCounter = 498000; // make it blink immediately

void LEDPulse(void)
{
    HeartbeatCounter++;
    if (HeartbeatCounter > 498000) {
        L_LED_ON();
    }
    if (HeartbeatCounter > 500000) {
        L_LED_OFF();
        HeartbeatCounter = 0;
    }
}


static int16_t UsbReceiveByte() {
	return CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
}

static int8_t UsbSendByte(uint8_t byte) {
	return CDC_Device_SendByte(&VirtualSerial_CDC_Interface, byte);
}


static int8_t UsbSendData(const uint8_t* const bytes, uint16_t len) {
	return CDC_Device_SendData(&VirtualSerial_CDC_Interface, bytes, len);
}

static int8_t UsbSendData_P(const uint8_t* const bytes, uint16_t len) {
	return CDC_Device_SendData_P(&VirtualSerial_CDC_Interface, bytes, len);
}

static int8_t UsbSendString(const char* const str) {
	return CDC_Device_SendString(&VirtualSerial_CDC_Interface, str);
}

static int8_t UsbSendString_P(const char* const str) {
	return CDC_Device_SendString_P(&VirtualSerial_CDC_Interface, str);
}


void main () {
    LED_SETUP();

	/* Initialize USB Subsystem */
	USB_Init();

	/* Enable global interrupts so that the USB stack can function */
	sei();

#define PINS \
    X(D, 3, 'A') \
    X(D, 2, 'B') \
    X(D, 1, 'C') \
    X(D, 0, 'D') \
    X(D, 4, 'E') \
    X(C, 6, 'F') \
    X(D, 7, 'G') \
    X(E, 6, 'H') \
    X(B, 4, 'I') \
    X(B, 5, 'J') \
    X(B, 6, 'K') \
    X(B, 2, 'L') \
    X(B, 3, 'M') \
    X(B, 1, 'N') \
    X(F, 7, 'O') \
    X(F, 6, 'P') \
    X(F, 5, 'Q') \
    X(F, 4, 'R')

#define X(port, pin, ch) DDR##port |= _BV(pin);
    PINS
#undef X

	for (;;)
	{
        LEDPulse();

		int16_t readch = UsbReceiveByte();

		if (readch > 0 && readch != '\r' && readch != '\n') {
            DATA_LED_ON();
            DataBlinkCounter = 1000; // this makes a pretty short blink
            bool valid = 0;

            if (readch == '0') {
                valid = 1;
                #define X(port, pin, ch) \
                    PORT##port &= ~_BV(pin);
                PINS
                #undef X
            } else if (readch == '1') {
                valid = 1;
                #define X(port, pin, ch) \
                    PORT##port |= _BV(pin);
                PINS
                #undef X
            } else
            // xmacro magic
#define X(port, pin, ch)                       \
            if (readch == ch) {                \
                PORT##port |= _BV(pin);        \
                valid = 1;                     \
            } else if (readch == (ch + 32)) {  /* lowercase */  \
                PORT##port &= ~_BV(pin);       \
                valid = 1;                     \
            } else
            PINS
            /* last else */ {}
#undef X

            if (valid) {
                UsbSendByte(readch);
            } else {
                UsbSendByte('?');
            }
		}

		if (DataBlinkCounter > 0) {
			DataBlinkCounter--;
		} else {
			DATA_LED_OFF();
		}

		CDC_Device_USBTask(&VirtualSerial_CDC_Interface);
		USB_USBTask();
	}
}

/** Event handler for the library USB Connection event. */
void EVENT_USB_Device_Connect(void)
{
	//
}

/** Event handler for the library USB Disconnection event. */
void EVENT_USB_Device_Disconnect(void)
{
	//
}

/** Event handler for the library USB Configuration Changed event. */
void EVENT_USB_Device_ConfigurationChanged(void)
{
	bool ConfigSuccess = true;
	ConfigSuccess &= CDC_Device_ConfigureEndpoints(&VirtualSerial_CDC_Interface);
}

/** Event handler for the library USB Control Request reception event. */
void EVENT_USB_Device_ControlRequest(void)
{
	CDC_Device_ProcessControlRequest(&VirtualSerial_CDC_Interface);
}


/** Event handler for the CDC Class driver Line Encoding Changed event.
 *
 *  \param[in] CDCInterfaceInfo  Pointer to the CDC class interface configuration structure being referenced
 */
void EVENT_CDC_Device_LineEncodingChanged(USB_ClassInfo_CDC_Device_t* const CDCInterfaceInfo)
{
	//
}