Add samples about SERCOM as USART

sercom-usart/samd21sercom.cpp

@@ -0,0 +1,105 @@
+#include "sam.h"
+#include "samd21sercom.h"
+
+void SAMD21SercomUsart::init(char sercomNum, char clkGen, SAMD21SercomUsartConfig_t *_config)
+{
+	config = _config;
+	char sercomPmMask = 0;
+	char sercomClk = 0;
+	IRQn_Type sercom_irqn = (IRQn_Type)0;
+	sercom = (Sercom *)0;
+	switch(sercomNum)	//Select correct SERCOM
+	{
+		case 0:
+			sercomPmMask = PM_APBCMASK_SERCOM0;
+			sercomClk = GCLK_CLKCTRL_ID_SERCOM0_CORE;
+			sercom_irqn = SERCOM0_IRQn;
+			sercom = SERCOM0;
+			break;
+		case 1:
+			sercomPmMask = PM_APBCMASK_SERCOM1;
+			sercomClk = GCLK_CLKCTRL_ID_SERCOM1_CORE;
+			sercom_irqn = SERCOM1_IRQn;
+			sercom = SERCOM1;
+			break;
+		case 2:
+			sercomPmMask = PM_APBCMASK_SERCOM2;
+			sercomClk = GCLK_CLKCTRL_ID_SERCOM2_CORE;
+			sercom_irqn = SERCOM2_IRQn;
+			sercom = SERCOM2;
+			break;
+		case 3:
+			sercomPmMask = PM_APBCMASK_SERCOM3;
+			sercomClk = GCLK_CLKCTRL_ID_SERCOM3_CORE;
+			sercom_irqn = SERCOM3_IRQn;
+			sercom = SERCOM3;
+			break;
+		case 4:
+			sercomPmMask = PM_APBCMASK_SERCOM4;
+			sercomClk = GCLK_CLKCTRL_ID_SERCOM4_CORE;
+			sercom_irqn = SERCOM4_IRQn;
+			sercom = SERCOM4;
+			break;
+		case 5:
+			sercomPmMask = PM_APBCMASK_SERCOM5;
+			sercomClk = GCLK_CLKCTRL_ID_SERCOM5_CORE;
+			sercom_irqn = SERCOM5_IRQn;
+			sercom = SERCOM5;
+			break;
+	}
+	PM->APBCMASK.reg			|=	sercomPmMask;											//Deliver clock to SERCOM
+	GCLK->CLKCTRL.reg			=	sercomClk												//Clock for correct SERCOM
+								|	(clkGen	<<	GCLK_CLKCTRL_GEN_Pos)						//Use correct GCLK Generator
+								|	GCLK_CLKCTRL_CLKEN;										//Enable clock
+	sercom->USART.CTRLA.reg		=	SERCOM_USART_CTRLA_MODE_USART_INT_CLK					//USART with internal clock
+								|	(config->sampleRate	<<	SERCOM_USART_CTRLA_SAMPR_Pos)	//Given sample rate
+								|	(config->txPos	<<	SERCOM_USART_CTRLA_TXPO_Pos)		//Given TX position
+								|	(config->rxPo	<<	SERCOM_USART_CTRLA_RXPO_Pos)		//Given RX position
+								|	(0	<<	SERCOM_USART_CTRLA_SAMPA_Pos)					//Middle sample adjustment
+								|	(config->comMode	<<	SERCOM_USART_CTRLA_CMODE_Pos)	//Given communication mode
+								|	(config->dataOrder	<<	SERCOM_USART_CTRLA_DORD_Pos);	//Given data order
+	sercom->USART.CTRLB.reg		=	(config->txEn ? SERCOM_USART_CTRLB_TXEN : 0)			//Enable or disable TX
+								|	(config->rxEn ? SERCOM_USART_CTRLB_RXEN : 0);			//Enable or disable RX
+	sercom->USART.BAUD.reg		=	config->baud;											//Given baud rate
+	sercom->USART.INTENSET.reg	=	(config->intRxComplete ? SERCOM_USART_INTENSET_RXC : 0);//Enable or disable receive complete interrupt
+	sercom->USART.CTRLA.reg		|=	SERCOM_USART_CTRLA_ENABLE;								//Enable SERCOM
+
+	if(config->intRxComplete) NVIC_EnableIRQ(sercom_irqn);									//Enable or not SERCOM interrupt
+}
+
+void SAMD21SercomUsart::send(char data)
+{
+	while(!(sercom->USART.INTFLAG.reg	&	SERCOM_USART_INTFLAG_DRE));	//Wait for data buffer
+	sercom->USART.DATA.reg	=	data;									//Send
+}
+
+void SAMD21SercomUsart::sendStr(char *str)
+{
+	while(*str != 0)	//If pointed char is not 0
+	{
+		send(*str);		//Send pointed char
+		str++;			//Move pointer forward
+	}
+}
+
+char SAMD21SercomUsart::available(void)
+{
+	if(sercom->USART.INTFLAG.reg	&	SERCOM_USART_INTFLAG_RXC)	//If there are received data
+	{
+		return 1;
+	}
+	else
+	{
+		return 0;
+	}
+}
+
+char SAMD21SercomUsart::read(void)
+{
+	char data = 0;
+	if(available())	//If data has been received
+	{
+		data = sercom->USART.DATA.reg;	//Read received data
+	}
+	return data;
+}

sercom-usart/samd21sercom.h

@@ -0,0 +1,49 @@
+#ifndef SAMD21SERCOM_H
+#define SAMD21SERCOM_H
+
+#include "sam.h"
+
+typedef struct SAMD21SercomUsartConfig
+{
+	char sampleRate;
+	char txPos;
+	char rxPo;
+	char format;
+	char comMode;
+	char dataOrder;
+	char charSize;
+	char stopBits;
+	char parityMode;
+	char txEn;
+	char rxEn;
+	int baud;
+	char intRxComplete;
+} SAMD21SercomUsartConfig_t;
+
+class SAMD21SercomUsart
+{
+	public:
+		//Configuration of USART
+		SAMD21SercomUsartConfig *config;
+
+		//Initializing function
+		//Note: this configures clock delivery, but user must configure I/O pins!
+		void init(char sercomNum, char clkGen, SAMD21SercomUsartConfig_t *_config);
+
+		//Send data
+		void send(char data);
+
+		//Send string
+		//String must have 0 at end
+		void sendStr(char *str);
+
+		//This function checks is there are received data
+		char available(void);
+
+		//Read received data
+		char read(void);
+	private:
+		Sercom *sercom;
+};
+
+#endif