microbit-dal/source/MicroBitI2C.cpp

92 lines
2.8 KiB
C++

#include "mbed.h"
#include "MicroBit.h"
#include "twi_master.h"
#include "nrf_delay.h"
/**
* Constructor.
* Create an instance of i2c
* @param sda the Pin to be used for SDA
* @param scl the Pin to be used for SCL
* Example:
* @code
* MicroBitI2C i2c(MICROBIT_PIN_SDA, MICROBIT_PIN_SCL);
* @endcode
* @note this should prevent i2c lockups as well.
*/
MicroBitI2C::MicroBitI2C(PinName sda, PinName scl) : I2C(sda,scl)
{
this->retries = 0;
}
/**
* Performs a complete read transaction. The bottom bit of the address is forced to 1 to indicate a read.
*
* @address 8-bit I2C slave address [ addr | 1 ]
* @data Pointer to the byte-array to read data in to
* @length Number of bytes to read
* @repeated Repeated start, true - don't send stop at end.
*
* @return MICROBIT_OK on success, MICROBIT_I2C_ERROR if an unresolved read failure is detected.
*/
int MicroBitI2C::read(int address, char *data, int length, bool repeated)
{
int result = I2C::read(address,data,length,repeated);
//0 indicates a success, presume failure
while(result != 0 && retries < MICROBIT_I2C_MAX_RETRIES)
{
_i2c.i2c->EVENTS_ERROR = 0;
_i2c.i2c->ENABLE = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
_i2c.i2c->POWER = 0;
nrf_delay_us(5);
_i2c.i2c->POWER = 1;
_i2c.i2c->ENABLE = TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos;
twi_master_init_and_clear();
result = I2C::read(address,data,length,repeated);
retries++;
}
if(result != 0)
return MICROBIT_I2C_ERROR;
retries = 0;
return MICROBIT_OK;
}
/**
* Performs a complete write transaction. The bottom bit of the address is forced to 0 to indicate a write.
*
* @address 8-bit I2C slave address [ addr | 0 ]
* @data Pointer to the byte-arraycontaining the data to write
* @length Number of bytes to write
* @repeated Repeated start, true - don't send stop at end.
*
* @return MICROBIT_OK on success, MICROBIT_I2C_ERROR if an unresolved write failure is detected.
*/
int MicroBitI2C::write(int address, const char *data, int length, bool repeated)
{
int result = I2C::write(address,data,length,repeated);
//0 indicates a success, presume failure
while(result != 0 && retries < MICROBIT_I2C_MAX_RETRIES)
{
_i2c.i2c->EVENTS_ERROR = 0;
_i2c.i2c->ENABLE = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
_i2c.i2c->POWER = 0;
nrf_delay_us(5);
_i2c.i2c->POWER = 1;
_i2c.i2c->ENABLE = TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos;
twi_master_init_and_clear();
result = I2C::write(address,data,length,repeated);
retries++;
}
if(result != 0)
return MICROBIT_I2C_ERROR;
retries = 0;
return MICROBIT_OK;
}