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Be more compliant in the I2C protocol

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- Enter a repeated-start for reading data
- Write in the same session
This commit is contained in:
Yuri D'Elia 2020-09-28 20:21:07 +02:00
parent 384f40956c
commit c2e8d229a7
3 changed files with 89 additions and 47 deletions
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6
Firmware/pat9125.c
View file

@ -263,8 +263,7 @@ uint8_t pat9125_rd_reg(uint8_t addr)
if (!swi2c_readByte_A8(PAT9125_I2C_ADDR, addr, &data)) //NO ACK error
goto error;
#elif defined(PAT9125_I2C)
if (twi_rw8(PAT9125_I2C_ADDR,TW_WRITE,&addr) ||
twi_rw8(PAT9125_I2C_ADDR,TW_READ,&data))
if (twi_r8(PAT9125_I2C_ADDR,addr,&data))
goto error;
#endif
return data;
@ -286,8 +285,7 @@ void pat9125_wr_reg(uint8_t addr, uint8_t data)
if (!swi2c_writeByte_A8(PAT9125_I2C_ADDR, addr, &data)) //NO ACK error
goto error;
#elif defined(PAT9125_I2C)
if (twi_rw8(PAT9125_I2C_ADDR,TW_WRITE,&addr) ||
twi_rw8(PAT9125_I2C_ADDR,TW_READ,&data))
if (twi_w8(PAT9125_I2C_ADDR,addr,data))
goto error;
#endif
return;

110
Firmware/twi.c
View file

@ -48,55 +48,89 @@ void twi_disable(void)
digitalWrite(SCL, 0);
}
static void twi_wait()
static void twi_stop()
{
while(!(TWCR & _BV(TWINT)));
TWCR = _BV(TWEN) | _BV(TWINT) | _BV(TWSTO);
}
uint8_t twi_rw8(uint8_t address, uint8_t mode, uint8_t* data)
static uint8_t twi_wait(uint8_t status)
{
while(!(TWCR & _BV(TWINT)));
if(TW_STATUS != status)
{
twi_stop();
return 1;
}
return 0;
}
static uint8_t twi_start(uint8_t address, uint8_t reg)
{
// send start condition
TWCR = _BV(TWEN) | _BV(TWINT) | _BV(TWSTA);
twi_wait();
if(TW_STATUS != TW_START)
if(twi_wait(TW_START))
return 1;
// send address
TWDR = mode;
TWDR |= (address << 1);
TWDR = TW_WRITE | (address << 1);
TWCR = _BV(TWEN) | _BV(TWINT);
twi_wait();
if(twi_wait(TW_MT_SLA_ACK))
return 2;
if(mode == TW_WRITE)
{
if(TW_STATUS != TW_MT_SLA_ACK)
return 2;
// send data
TWDR = *data;
TWCR = _BV(TWEN) | _BV(TWINT);
twi_wait();
if(TW_STATUS != TW_MT_DATA_ACK)
return 3;
}
else
{
if(TW_STATUS != TW_MR_SLA_ACK)
return 2;
// receive data
TWCR = _BV(TWEN) | _BV(TWINT);
twi_wait();
// accept ACK or NACK (since only 1 byte is read)
if(!(TW_STATUS & TW_MR_DATA_ACK))
return 3;
*data = TWDR;
}
// send stop
TWCR = _BV(TWEN) | _BV(TWINT) | _BV(TWSTO);
// send register
TWDR = reg;
TWCR = _BV(TWEN) | _BV(TWINT);
if(twi_wait(TW_MT_DATA_ACK))
return 3;
return 0;
}
uint8_t twi_r8(uint8_t address, uint8_t reg, uint8_t* data)
{
if(twi_start(address, reg))
return 1;
// repeat start
TWCR = _BV(TWEN) | _BV(TWINT) | _BV(TWSTA);
if(twi_wait(TW_REP_START))
return 2;
// start receiving
TWDR = TW_READ | (address << 1);
TWCR = _BV(TWEN) | _BV(TWINT);
if(twi_wait(TW_MR_SLA_ACK))
return 3;
// receive data
TWCR = _BV(TWEN) | _BV(TWINT);
if(twi_wait(TW_MR_DATA_NACK))
return 4;
*data = TWDR;
// send stop
twi_stop();
return 0;
}
uint8_t twi_w8(uint8_t address, uint8_t reg, uint8_t data)
{
if(twi_start(address, reg))
return 1;
// send data
TWDR = data;
TWCR = _BV(TWEN) | _BV(TWINT);
if(twi_wait(TW_MT_DATA_ACK))
return 2;
// send stop
twi_stop();
return 0;
}

20
Firmware/twi.h
View file

@ -43,11 +43,21 @@ void twi_init(void);
void twi_disable(void);
/*
* Function twi_rw8
* Desc read/write a single byte from a device
* Function twi_r8
* Desc read a single byte from a device
* Input address: 7bit i2c device address
* mode: TW_READ or TW_WRITE
* data: pointer to byte
* reg: register address
* data: pointer to byte for result
* Output 0 on success
*/
uint8_t twi_rw8(uint8_t address, uint8_t mode, uint8_t* data);
uint8_t twi_r8(uint8_t address, uint8_t reg, uint8_t* data);
/*
* Function twi_w8
* Desc write a single byte from a device
* Input address: 7bit i2c device address
* reg: register address
* data: byte to write
* Output 0 on success
*/
uint8_t twi_w8(uint8_t address, uint8_t reg, uint8_t data);