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--- courses:be5b99cpl:labs:lab05 [2018/10/04 15:47]
+++ courses:be5b99cpl:labs:lab05 [2018/10/04 15:47] (current)
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+====== Lab05 - Hardware initialization ======
+This exercise deals with NUCLEO I/O initialization of the User LED and User Button. The exercise also deals with usage of these resources. The definition of the LED and Button connection is described in the board [[http://www.st.com/resource/en/user_manual/dm00105823.pdf|user manual]].
+Task:
+  * Find the CPU pin and port for the User LED (green) output control.
+  * Find the CPU pin and port for the User Button input control.
+==== LED ====
+The NUCLEO board contains a green LED controlled by the CPU. The LED is connected to the CPU pin XX of the port GPIOXX. The output needs to be initialized through the GPIO_Init function as depicted below. The initialization should be placed into void GPIO_Configuration( void ) function of the project.
+<code>
+  // PXX = USER LED
+  GPIO_InitStructure.GPIO_Pin         = GPIO_Pin_XX;
+  GPIO_InitStructure.GPIO_Mode        = GPIO_Mode_OUT;
+  GPIO_InitStructure.GPIO_OType       = GPIO_OType_PP;
+  GPIO_InitStructure.GPIO_Speed       = GPIO_Speed_50MHz;
+  GPIO_InitStructure.GPIO_PuPd        = GPIO_PuPd_UP;
+  GPIO_Init( GPIOXX, &GPIO_InitStructure );
+</code>
+==== Button ====
+The user button is hardwired to a different port then LED and USART. This means the respective GPIO needs to be initialized and connected to the clock source. This operation should be done in void RCC_Configuration( void ) function: see below.
+<code>
+  // GPIOC clock enable
+  RCC_AHB1PeriphClockCmd( RCC_AHB1Periph_GPIOC, ENABLE );
+</code>
+The initialization of the input pin is performed in the same way as the output pin with small difference: GPIO_Mode_IN.
+<code>
+  // PXX = USER Button
+  GPIO_InitStructure.GPIO_Pin         = GPIO_Pin_XX;
+  GPIO_InitStructure.GPIO_Mode        = GPIO_Mode_IN;
+  GPIO_InitStructure.GPIO_OType       = GPIO_OType_PP;
+  GPIO_InitStructure.GPIO_Speed       = GPIO_Speed_50MHz;
+  GPIO_InitStructure.GPIO_PuPd        = GPIO_PuPd_UP;
+  GPIO_Init( GPIOXX, &GPIO_InitStructure );
+</code>
+==== Main function ====
+The setting of the output can be done through GPIO_SetBits and GPIO_ResetBits (or GPIO_ToggleBits). The input can be read through GPIO_ReadInputDataBit. The list of functions available for input output manipulation is described in stm32f4xx_gpio.h.
+<code>
+int main(void)
+{
+	// Init
+	RCC_Configuration();
+	GPIO_Configuration();
+	USART2_Configuration();
+	// Process
+	OutString("Welcome to Nucleo F401RE\r\n");
+	while(1) // Don't want to exit
+	{
+		uint16_t Data;
+		uint8_t btData;
+		while(USART_GetFlagStatus(USART2, USART_FLAG_RXNE) == RESET); // Wait for Char
+		Data = USART_ReceiveData(USART2); // Collect Char
+		OutString("Welcome to Nucleo F401RE\r\n");
+		USART_SendData(USART2, Data); // Echo Char
+		OutString("\n");
+		GPIO_ToggleBits( GPIOA, GPIO_Pin_5 );
+		btData = GPIO_ReadInputDataBit( GPIOC, GPIO_Pin_13 );
+		if( !btData )
+		{
+			OutString("Butt press\r\n");
+		}
+	} // END while(1)
+} // END main
+</code>
+==== Exercise ====
+  * Use the initialization of the HW components and provide interface which allows you to read/write the state to the inputs/outputs.
+  * Adjust the program developed in HomeWork 01 to be able to:
+     * Read the state of the button.
+     * Write the state of the User LED.