I2C 使用Microchip plib

本篇以dsPIC30F為主。

plib 安裝

到Legacy PIC24 MCU & dsPIC DSC Peripheral Library下載最新的plib，然後她會要求將plib安裝到你電腦中xc16 complier的資料夾下(linux在”/opt/microchip/xc16”下)。

函式概覽

安裝後文件會在xc16 complier的docs/periph_libs下。
其中plib提供以下函式。

AckI2C
CloseI2C
ConfigIntI2C
DataRdyI2C
IdleI2C
MastergetsI2C
MasterputsI2C
MasterReadI2C
MasterWriteI2C
NotAckI2C
OpenI2C
RestartI2C
SlavegetsI2C
SlaveputsI2C
SlaveReadI2C
SlaveWriteI2C
StartI2C
StopI2C

還有一些MARCO

EnableIntMI2C
DiableIntMI2C
SetPriorityIntMI2C
EnableIntSI2C
DisableIntSI2C
SetPriorityIntSI2C

這份文件16 bit language tools第191頁開始有詳述這些函式的介面。所以本文主要會面向如何運用這些函式達成master與slave溝通。

I2C (dsPIC30F as Master with 7bit address)

reception

以下圖片來自於http://ww1.microchip.com/downloads/en/DeviceDoc/70046E.pdf

對應到plib的流程為。(以下為我在i2cdevlib中所新增的片段，為一次讀多個bytes)。

	Master |S |Device Addr+W| |Reg Addr| |S |Device Addr+R| | |NACK|P|
	Slave | | |ACK| |ACK| | |ACK|DATA| | |

view raw I2C_read_seq hosted with ❤ by GitHub

請先透過ConfigIntI2C和OpenI2C設定好硬體參數。

	IFS0bits.MI2CIF = 0;
	IEC0bits.MI2CIE = 0;
	/*master Start*/
	StartI2C();
	/* Clear interrupt flag */
	/* Wait till Start sequence is completed */
	while(I2CCONbits.SEN);
	/*master send AD+W*/
	/* Write Slave Address (Write)*/
	MasterWriteI2C(devAddr << 1 | 0x00);
	/* Wait until address is transmitted */
	while(I2CSTATbits.TBF); // 8 clock cycles
	/*Slave send Ack*/
	while(!IFS0bits.MI2CIF); // Wait for 9th clock cycle
	IFS0bits.MI2CIF = 0; // Clear interrupt flag
	while(I2CSTATbits.ACKSTAT);
	/*Master send RA*/
	/* Write Register Address */
	MasterWriteI2C(regAddr);
	/* Wait until address is transmitted */
	while(I2CSTATbits.TBF); // 8 clock cycles
	/*Slave send ACK*/
	while(!IFS0bits.MI2CIF); // Wait for 9th clock cycle
	IFS0bits.MI2CIF = 0; // Clear interrupt flag
	while(I2CSTATbits.ACKSTAT);
	/*Master Pause*/
	StopI2C();
	/* Wait till stop sequence is completed */
	while(I2CCONbits.PEN);
	/*Master Start*/
	StartI2C();
	/* Wait till Start sequence is completed */
	while(I2CCONbits.SEN);
	/*Master send AD+R*/
	/* Write Slave Address (Read)*/
	MasterWriteI2C(devAddr << 1 | 0x01);
	/* Wait until address is transmitted */
	while(I2CSTATbits.TBF); // 8 clock cycles
	/*Slave send Ack*/
	while(!IFS0bits.MI2CIF); // Wait for 9th clock cycle
	IFS0bits.MI2CIF = 0; // Clear interrupt flag
	while(I2CSTATbits.ACKSTAT);
	data[0] = MasterReadI2C();
	unsigned int i;
	for (i = 1 ; i < length ; i++ ){
	AckI2C();
	while(I2CCONbits.ACKEN == 1);
	data[i] = MasterReadI2C();
	}
	NotAckI2C();
	while(I2CCONbits.ACKEN == 1);
	/*Master Pause*/
	StopI2C();
	/* Wait till stop sequence is completed */
	while(I2CCONbits.PEN);

view raw I2C_read.cpp hosted with ❤ by GitHub

值得注意的是在dsPIC30F manual中第5步驟。要透過StartI2C再次產生start condition。而讀入多個data bytes可用MastergetsI2C函式。

transmission

transmission只要全部都由Master端給資料即可。
對應到plib的流程為。(以下為我在i2cdevlib中所新增的片段，為一次寫多個bytes)。

	Master |S |Device Addr+W| |Reg Addr| |DATA| |P|
	Slave | | |ACK| |ACK| |ACK | |

view raw I2C_write_seq hosted with ❤ by GitHub

請先透過ConfigIntI2C和OpenI2C設定好硬體參數。

	IFS0bits.MI2CIF = 0;
	IEC0bits.MI2CIE = 0;
	/*Master Start*/
	StartI2C();
	/* Wait util Start sequence is completed */
	while(I2CCONbits.SEN);
	/* Clear interrupt flag */
	IFS0bits.MI2CIF = 0;
	/*Master send AD+W*/
	/* Write Slave address (Write)*/
	MasterWriteI2C(devAddr << 1 | 0x00);
	/* Wait till address is transmitted */
	while(I2CSTATbits.TBF); // 8 clock cycles
	/*Slave send ACK*/
	while(!IFS0bits.MI2CIF); // Wait for 9th clock cycle
	IFS0bits.MI2CIF = 0; // Clear interrupt flag
	while(I2CSTATbits.ACKSTAT);
	/*Master send RA*/
	/* Write Slave address (Write)*/
	MasterWriteI2C(regAddr);
	/* Wait till address is transmitted */
	while(I2CSTATbits.TBF); // 8 clock cycles
	/*Slave send ACK*/
	while(!IFS0bits.MI2CIF); // Wait for 9th clock cycle
	IFS0bits.MI2CIF = 0; // Clear interrupt flag
	while(I2CSTATbits.ACKSTAT);
	/*Master send data*/
	/* Transmit string of data */
	uint8_t i;
	for (i = 0 ; i < length ; i++){
	MasterWriteI2C(data[i]);
	/* Wait till address is transmitted */
	while(I2CSTATbits.TBF); // 8 clock cycles
	/*Slave send ACK*/
	while(!IFS0bits.MI2CIF); // Wait for 9th clock cycle
	IFS0bits.MI2CIF = 0; // Clear interrupt flag
	}
	StopI2C();
	/* Wait till stop sequence is completed */
	while(I2CCONbits.PEN);

view raw I2C_write.cpp hosted with ❤ by GitHub

Written with StackEdit.