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I2C Bit-Bangging - MSP430
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| /******************************************************************************** | |
| Module : I2C_SW | |
| Author : 05/04/2015, by KienLTb - https://kienltb.wordpress.com/ | |
| Description : I2C software using bit-banging. | |
| ********************************************************************************/ | |
| /*-----------------------------------------------------------------------------*/ | |
| /* Header inclusions */ | |
| /*-----------------------------------------------------------------------------*/ | |
| #include "msp430g2553.h" | |
| #include "i2c_sw.h" | |
| /*-----------------------------------------------------------------------------*/ | |
| /* Local Macro definitions */ | |
| /*-----------------------------------------------------------------------------*/ | |
| /*-----------------------------------------------------------------------------*/ | |
| /* Function prototypes */ | |
| /*-----------------------------------------------------------------------------*/ | |
| unsigned char Read_SCL(void); | |
| unsigned char Read_SDA(void); | |
| void Clear_SCL(void); | |
| void Clear_SDA(void); | |
| void I2C_Init(void); | |
| void I2C_Start(void); | |
| void I2C_Stop(void); | |
| void I2C_Writebit(unsigned char bit); | |
| unsigned char I2C_ReadByte(void); | |
| void I2C_WriteByte(unsigned char Data); | |
| unsigned char I2C_ReadByte(void); | |
| void I2C_WriteData(unsigned char *Data, unsigned char DevideAddr, unsigned char Register, unsigned char nLength); | |
| void I2C_ReadData(unsigned char *Buff, unsigned char DevideAddr, unsigned char Register, unsigned char nLength); | |
| /*-----------------------------------------------------------------------------*/ | |
| /* Function implementations */ | |
| /*-----------------------------------------------------------------------------*/ | |
| /*-------------------------------------------------------------------------------- | |
| Function : Read_SCL | |
| Purpose : Set SCL as input and return current Logic level of SCL (0 or 1) | |
| nomal is 1 because pullup by resistor | |
| Parameters : None | |
| Return : Logic level of SCL pin | |
| --------------------------------------------------------------------------------*/ | |
| unsigned char Read_SCL(void) | |
| { | |
| I2C_PxDIR &= ~SCL; | |
| return((I2C_PxIN & SCL) != 0); | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : Read_SDA | |
| Purpose : Set SDA as input and return current Logic level of SDA (0 or 1), | |
| nomal is 1 because pullup by resistor | |
| Parameters : None | |
| Return : Logic level of SDA pin | |
| --------------------------------------------------------------------------------*/ | |
| unsigned char Read_SDA(void) | |
| { | |
| I2C_PxDIR &= ~SDA; | |
| return((I2C_PxIN & SDA) != 0); | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : Clear_SCL | |
| Purpose : Set SCL as Out put, logic Low | |
| Parameters : None | |
| Return : None | |
| --------------------------------------------------------------------------------*/ | |
| void Clear_SCL(void) | |
| { | |
| I2C_PxDIR |= SCL; | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : Clear_SDA | |
| Purpose : Set SDA as Out put, logic LOW | |
| Parameters : None | |
| Return : None | |
| --------------------------------------------------------------------------------*/ | |
| void Clear_SDA(void) | |
| { | |
| I2C_PxDIR |= SDA; | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : I2C_Init | |
| Purpose : Initialize I2C block | |
| Parameters : None | |
| Return : None | |
| --------------------------------------------------------------------------------*/ | |
| void I2C_Init(void) | |
| { | |
| // Conffig SCL and SDA as GPIO | |
| I2C_PxSEL &= ~(SCL + SDA); | |
| I2C_PxSEL2 &= ~(SCL + SDA); | |
| // Set SCL and SDA is logic HIGH | |
| I2C_PxDIR &= ~(SCL + SDA); | |
| I2C_PxOUT &= ~(SCL + SDA); | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : I2C_Start | |
| Purpose : Send start signal | |
| Parameters : None | |
| Return : None | |
| --------------------------------------------------------------------------------*/ | |
| void I2C_Start(void) | |
| { | |
| Read_SDA(); //set SDA to 1 | |
| I2C_DELAY(); | |
| Clear_SDA(); //set SDA to 0, currently SCL is 1 | |
| I2C_DELAY(); | |
| Clear_SCL(); //set SCL to 0 | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : I2C_Stop | |
| Purpose : Send Stop signal | |
| Parameters : None | |
| Return : None | |
| --------------------------------------------------------------------------------*/ | |
| void I2C_Stop(void) | |
| { | |
| Clear_SDA(); //set SDA to 0 | |
| I2C_DELAY(); | |
| Read_SCL(); //set SCL to 1 | |
| I2C_DELAY(); | |
| Read_SDA(); //set SDA to 1 | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : I2C_Writebit | |
| Purpose : Write bit to I2C bus | |
| Parameters : a bit need to write | |
| Return : None | |
| --------------------------------------------------------------------------------*/ | |
| void I2C_Writebit(unsigned char bit) | |
| { | |
| if(bit) | |
| Read_SDA(); | |
| else | |
| Clear_SDA(); | |
| I2C_DELAY(); | |
| Read_SCL(); | |
| I2C_DELAY(); | |
| Clear_SCL(); | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : I2C_Readbit | |
| Purpose : Read bit to I2C bus | |
| Parameters : None | |
| Return : unsigned char | |
| --------------------------------------------------------------------------------*/ | |
| unsigned char I2C_Readbit(void) | |
| { | |
| unsigned char bit; | |
| //Let the slave driver data | |
| Read_SDA(); | |
| I2C_DELAY(); | |
| Read_SCL(); | |
| bit = Read_SDA(); | |
| I2C_DELAY(); | |
| Clear_SCL(); | |
| return bit; | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : I2C_WriteByte | |
| Purpose : Write a Byte to I2C bus | |
| Parameters : unsigned char Data | |
| Return : None | |
| --------------------------------------------------------------------------------*/ | |
| void I2C_WriteByte(unsigned char Data) | |
| { | |
| unsigned char nBit; | |
| for(nBit = 0; nBit < 8; nBit++) | |
| { | |
| I2C_Writebit((Data & 0x80) != 0); | |
| Data <<= 1; | |
| } | |
| I2C_Readbit(); // Waite NACK | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : I2C_ReadByte | |
| Purpose : Read a Byte to I2C bus | |
| Parameters : None | |
| Return : unsigned char | |
| --------------------------------------------------------------------------------*/ | |
| unsigned char I2C_ReadByte(void) | |
| { | |
| unsigned char Buff = 0; | |
| unsigned char nBit; | |
| for(nBit = 0; nBit < 8; nBit++) | |
| { | |
| Buff = (Buff << 1) | I2C_Readbit(); | |
| } | |
| return Buff; | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : I2C_WriteData | |
| Purpose : Write n Byte to I2C bus | |
| Parameters : Data - Pointer to Data need to write | |
| DevideAddr - Devide Address | |
| Register - Register Address | |
| nLength - Number of Byte need to write | |
| Return : None | |
| --------------------------------------------------------------------------------*/ | |
| void I2C_WriteData(unsigned char *Data, unsigned char DevideAddr, unsigned char Register, unsigned char nLength) | |
| { | |
| unsigned char nIndex; | |
| I2C_Start(); | |
| I2C_WriteByte(DevideAddr << 1); // byDeviceAddr is 7 bit and command is write | |
| I2C_WriteByte(Register); | |
| for(nIndex = 0; nIndex < nLength; nIndex++) | |
| { | |
| I2C_WriteByte(*(Data + nIndex)); | |
| } | |
| I2C_Readbit(); | |
| I2C_Stop(); | |
| } | |
| /*-------------------------------------------------------------------------------- | |
| Function : I2C_ReadData | |
| Purpose : Read n Byte from I2C bus | |
| Parameters : Buff - Pointer to Buffer store value | |
| DevideAddr - Devide Address | |
| Register - Register Address | |
| nLength - Number of Byte need to read | |
| Return : None | |
| --------------------------------------------------------------------------------*/ | |
| void I2C_ReadData(unsigned char *Buff, unsigned char DevideAddr, unsigned char Register, unsigned char nLength) | |
| { | |
| unsigned char nIndex; | |
| I2C_Start(); | |
| I2C_WriteByte(DevideAddr << 1); | |
| I2C_WriteByte(Register); | |
| I2C_Stop(); | |
| _NOP(); // Short delay | |
| I2C_Start(); | |
| _NOP(); // Short delay | |
| I2C_WriteByte((DevideAddr << 1) | 1); | |
| for(nIndex = 0; nIndex < nLength; nIndex++) | |
| { | |
| *(Buff + nIndex) = I2C_ReadByte(); | |
| if(nIndex > 0)I2C_Writebit(ACK); | |
| } | |
| I2C_Writebit(NACK); | |
| I2C_Stop(); | |
| } |
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| /******************************************************************************** | |
| Module : I2C_SW | |
| Author : 05/04/2015, by KienLTb - https://kienltb.wordpress.com/ | |
| Description : I2C software using bit-banging. | |
| ********************************************************************************/ | |
| #ifndef _I2C_SW_H_ | |
| #define _I2C_SW_H_ | |
| /*-----------------------------------------------------------------------------*/ | |
| /* Macro definitions */ | |
| /*-----------------------------------------------------------------------------*/ | |
| /*-----------------------------------------------------------------------------*/ | |
| /* Local Macro definitions */ | |
| /*-----------------------------------------------------------------------------*/ | |
| #define I2C_PxSEL P1SEL | |
| #define I2C_PxSEL2 P1SEL2 | |
| #define I2C_PxDIR P1DIR | |
| #define I2C_PxOUT P1OUT | |
| #define I2C_PxIN P1IN | |
| #define SCL BIT6 | |
| #define SDA BIT7 | |
| #define ACK 0x00 | |
| #define NACK 0x01 | |
| #define TIME_DELAY 100 | |
| #define I2C_DELAY() __delay_cycles(TIME_DELAY) | |
| /*-----------------------------------------------------------------------------*/ | |
| /* Function prototypes */ | |
| /*-----------------------------------------------------------------------------*/ | |
| //NOTE: Need custom Read_SCL(), Read_SDA(), Clear_SCL(), Clear_SDA() to compatible Hardware. | |
| unsigned char Read_SCL(void); // Set SCL as input and return current level of line, 0 or 1, nomal is 1 because pullup by res | |
| unsigned char Read_SDA(void); // Set SDA as input and return current level of line, 0 or 1, nomal is 0 because pull by res | |
| void Clear_SCL(void); // Actively drive SCL signal Low | |
| void Clear_SDA(void); // Actively drive SDA signal Low | |
| void I2C_Init(void); | |
| void I2C_Start(void); | |
| void I2C_Stop(void); | |
| void I2C_Writebit(unsigned char bit); | |
| unsigned char I2C_Readbit(void); | |
| void I2C_WriteByte(unsigned char Data); | |
| unsigned char I2C_ReadByte(void); | |
| void I2C_WriteData(unsigned char *Data, unsigned char DevideAddr, unsigned char Register, unsigned char nLength); | |
| void I2C_ReadData(unsigned char *Buff, unsigned char DevideAddr, unsigned char Register, unsigned char nLength); | |
| #endif // _I2C_SW_H_ | |
https://gist.github.com/ksvbka/fec1f28ce40c276334fb#file-i2c_sw-c-L248
Multibyte read also fails on the I2C EEPROM. This like should look like this:
if(nIndex < nLength - 1) I2C_Writebit(ACK);
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Additional call of I2C_Readbit on the line 222 is causing issues on some I2C devices such as EEPROM (I wasn't able to write anything into the EEPROM until I've removed this line).
I2C_Readbit is called in the I2C_WriteByte function and doesn't need to be called again...