https://github.com/WebBluetoothCG/demos/pull/42
Dependencies: BLE_API mbed-dev-bin nRF51822
Fork of microbit-dal by
Diff: source/drivers/MicroBitI2C.cpp
- Revision:
- 1:8aa5cdb4ab67
- Child:
- 4:9fbeeb89de59
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/source/drivers/MicroBitI2C.cpp Thu Apr 07 01:33:22 2016 +0100 @@ -0,0 +1,134 @@ +/* +The MIT License (MIT) + +Copyright (c) 2016 British Broadcasting Corporation. +This software is provided by Lancaster University by arrangement with the BBC. + +Permission is hereby granted, free of charge, to any person obtaining a +copy of this software and associated documentation files (the "Software"), +to deal in the Software without restriction, including without limitation +the rights to use, copy, modify, merge, publish, distribute, sublicense, +and/or sell copies of the Software, and to permit persons to whom the +Software is furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in +all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL +THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING +FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER +DEALINGS IN THE SOFTWARE. +*/ + +#include "MicroBitConfig.h" +#include "MicroBitI2C.h" +#include "ErrorNo.h" +#include "twi_master.h" +#include "nrf_delay.h" + +/** + * Constructor. + * + * Create an instance of MicroBitI2C for I2C communication. + * + * @param sda the Pin to be used for SDA + * + * @param scl the Pin to be used for SCL + * + * @code + * MicroBitI2C i2c(I2C_SDA0, I2C_SCL0); + * @endcode + * + * @note This class presents a wrapped mbed call to capture failed I2C operations caused by a known silicon bug in the nrf51822. + * Attempts to automatically reset and restart the I2C hardware if this case is detected. + * + * For reference see PAN56 in: + * + * https://www.nordicsemi.com/eng/nordic/Products/nRF51822/PAN-nRF51822/24634 + * + * v2.0 through to v2.4 + */ +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. + * + * @param address 8-bit I2C slave address [ addr | 1 ] + * + * @param data A pointer to a byte buffer used for storing retrieved data. + * + * @param length Number of bytes to read. + * + * @param repeated if true, stop is not sent at the end. Defaults to false. + * + * @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. + * + * @param address 8-bit I2C slave address [ addr | 0 ] + * + * @param data A pointer to a byte buffer containing the data to write. + * + * @param length Number of bytes to write + * + * @param repeated if true, stop is not sent at the end. Defaults to false. + * + * @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; +}