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