#include <xpcc/architecture.hpp>
#include "../stm32f4_discovery.hpp"

// ----------------------------------------------------------------------------
/**
 * Very basic example of USART usage. 
 * The ASCII sequence 'A', 'B', 'C, ... , 'Z', 'A', 'B', 'C', ... 
 * is printed with 9600 baud, 8N1 at pin PA3.
 */
MAIN_FUNCTION
{
	defaultSystemClock::enable();

	LedOrange::setOutput(xpcc::Gpio::High);
	LedGreen::setOutput(xpcc::Gpio::Low);
	LedRed::setOutput(xpcc::Gpio::High);
	LedBlue::setOutput(xpcc::Gpio::High);

	// Enable USART 2
	GpioOutputA2::connect(Usart2::Tx);
	GpioInputA3::connect(Usart2::Rx, Gpio::InputType::PullUp);
	Usart2::initialize<defaultSystemClock, 9600>(12);

	while (1)
	{
		static uint8_t c = 'A';
		LedRed::toggle();
		LedGreen::toggle();
		Usart2::write(c);
		++c;
		if (c > 'Z') {
			c = 'A';
		}
		xpcc::delay_ms(500);
	}

	return 0;
}

#include <xpcc/architecture.hpp>
#include "../stm32f4_discovery.hpp"

// ----------------------------------------------------------------------------
MAIN_FUNCTION
{
	defaultSystemClock::enable();

	LedOrange::setOutput(xpcc::Gpio::High);
	LedGreen::setOutput(xpcc::Gpio::Low);
	LedRed::setOutput(xpcc::Gpio::High);
	LedBlue::setOutput(xpcc::Gpio::High);

	// Enable USART 2
	GpioOutputA2::connect(Usart2::Tx);
	GpioInputA3::connect(Usart2::Rx, Gpio::InputType::PullUp);
	Usart2::initialize<defaultSystemClock, 9600>(12);

	while (1)
	{
		static uint8_t c = 'A';
		LedRed::toggle();
		LedGreen::toggle();
		Usart2::write(c);
		++c;
		if (c == 'Z' + 1) {
			c = 'A';
		}
		xpcc::delay_ms(500);
	}

	return 0;
}

--- 
+++ 
@@ -2,6 +2,11 @@
 #include "../stm32f4_discovery.hpp"
 
 // ----------------------------------------------------------------------------
+/**
+ * Very basic example of USART usage. 
+ * The ASCII sequence 'A', 'B', 'C, ... , 'Z', 'A', 'B', 'C', ... 
+ * is printed with 9600 baud, 8N1 at pin PA3.
+ */
 MAIN_FUNCTION
 {
 	defaultSystemClock::enable();
@@ -23,7 +28,7 @@
 		LedGreen::toggle();
 		Usart2::write(c);
 		++c;
-		if (c == 'Z' + 1) {
+		if (c > 'Z') {
 			c = 'A';
 		}
 		xpcc::delay_ms(500);
Document what is expected from UART example