Neil Johnson / microbit-ARMBand

Official Sheffield ARMBand micro:bit program

microbit/microbit-dal/source/drivers/MicroBitI2C.cpp@0:b9164b348919, 2016-10-17 (annotated)

Committer:
MrBedfordVan
Date:
Mon Oct 17 12:41:20 2016 +0000
Revision:
0:b9164b348919
Official Sheffield ARMBand Micro:bit program

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MrBedfordVan 0:b9164b348919 1 /*
MrBedfordVan 0:b9164b348919 2 The MIT License (MIT)
MrBedfordVan 0:b9164b348919 3
MrBedfordVan 0:b9164b348919 4 Copyright (c) 2016 British Broadcasting Corporation.
MrBedfordVan 0:b9164b348919 5 This software is provided by Lancaster University by arrangement with the BBC.
MrBedfordVan 0:b9164b348919 6
MrBedfordVan 0:b9164b348919 7 Permission is hereby granted, free of charge, to any person obtaining a
MrBedfordVan 0:b9164b348919 8 copy of this software and associated documentation files (the "Software"),
MrBedfordVan 0:b9164b348919 9 to deal in the Software without restriction, including without limitation
MrBedfordVan 0:b9164b348919 10 the rights to use, copy, modify, merge, publish, distribute, sublicense,
MrBedfordVan 0:b9164b348919 11 and/or sell copies of the Software, and to permit persons to whom the
MrBedfordVan 0:b9164b348919 12 Software is furnished to do so, subject to the following conditions:
MrBedfordVan 0:b9164b348919 13
MrBedfordVan 0:b9164b348919 14 The above copyright notice and this permission notice shall be included in
MrBedfordVan 0:b9164b348919 15 all copies or substantial portions of the Software.
MrBedfordVan 0:b9164b348919 16
MrBedfordVan 0:b9164b348919 17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
MrBedfordVan 0:b9164b348919 18 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
MrBedfordVan 0:b9164b348919 19 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
MrBedfordVan 0:b9164b348919 20 THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
MrBedfordVan 0:b9164b348919 21 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
MrBedfordVan 0:b9164b348919 22 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
MrBedfordVan 0:b9164b348919 23 DEALINGS IN THE SOFTWARE.
MrBedfordVan 0:b9164b348919 24 */
MrBedfordVan 0:b9164b348919 25
MrBedfordVan 0:b9164b348919 26 #include "MicroBitConfig.h"
MrBedfordVan 0:b9164b348919 27 #include "MicroBitI2C.h"
MrBedfordVan 0:b9164b348919 28 #include "ErrorNo.h"
MrBedfordVan 0:b9164b348919 29 #include "twi_master.h"
MrBedfordVan 0:b9164b348919 30 #include "nrf_delay.h"
MrBedfordVan 0:b9164b348919 31
MrBedfordVan 0:b9164b348919 32 /**
MrBedfordVan 0:b9164b348919 33 * Constructor.
MrBedfordVan 0:b9164b348919 34 *
MrBedfordVan 0:b9164b348919 35 * Create an instance of MicroBitI2C for I2C communication.
MrBedfordVan 0:b9164b348919 36 *
MrBedfordVan 0:b9164b348919 37 * @param sda the Pin to be used for SDA
MrBedfordVan 0:b9164b348919 38 *
MrBedfordVan 0:b9164b348919 39 * @param scl the Pin to be used for SCL
MrBedfordVan 0:b9164b348919 40 *
MrBedfordVan 0:b9164b348919 41 * @code
MrBedfordVan 0:b9164b348919 42 * MicroBitI2C i2c(I2C_SDA0, I2C_SCL0);
MrBedfordVan 0:b9164b348919 43 * @endcode
MrBedfordVan 0:b9164b348919 44 *
MrBedfordVan 0:b9164b348919 45 * @note This class presents a wrapped mbed call to capture failed I2C operations caused by a known silicon bug in the nrf51822.
MrBedfordVan 0:b9164b348919 46 * Attempts to automatically reset and restart the I2C hardware if this case is detected.
MrBedfordVan 0:b9164b348919 47 * \par
MrBedfordVan 0:b9164b348919 48 * For reference see PAN56 in:
MrBedfordVan 0:b9164b348919 49 * \par
MrBedfordVan 0:b9164b348919 50 * https://www.nordicsemi.com/eng/nordic/Products/nRF51822/PAN-nRF51822/24634
MrBedfordVan 0:b9164b348919 51 * \par
MrBedfordVan 0:b9164b348919 52 * v2.0 through to v2.4
MrBedfordVan 0:b9164b348919 53 */
MrBedfordVan 0:b9164b348919 54 MicroBitI2C::MicroBitI2C(PinName sda, PinName scl) : I2C(sda,scl)
MrBedfordVan 0:b9164b348919 55 {
MrBedfordVan 0:b9164b348919 56 this->retries = 0;
MrBedfordVan 0:b9164b348919 57 }
MrBedfordVan 0:b9164b348919 58
MrBedfordVan 0:b9164b348919 59 /**
MrBedfordVan 0:b9164b348919 60 * Performs a complete read transaction. The bottom bit of the address is forced to 1 to indicate a read.
MrBedfordVan 0:b9164b348919 61 *
MrBedfordVan 0:b9164b348919 62 * @param address 8-bit I2C slave address [ addr | 1 ]
MrBedfordVan 0:b9164b348919 63 *
MrBedfordVan 0:b9164b348919 64 * @param data A pointer to a byte buffer used for storing retrieved data.
MrBedfordVan 0:b9164b348919 65 *
MrBedfordVan 0:b9164b348919 66 * @param length Number of bytes to read.
MrBedfordVan 0:b9164b348919 67 *
MrBedfordVan 0:b9164b348919 68 * @param repeated if true, stop is not sent at the end. Defaults to false.
MrBedfordVan 0:b9164b348919 69 *
MrBedfordVan 0:b9164b348919 70 * @return MICROBIT_OK on success, MICROBIT_I2C_ERROR if an unresolved read failure is detected.
MrBedfordVan 0:b9164b348919 71 */
MrBedfordVan 0:b9164b348919 72 int MicroBitI2C::read(int address, char *data, int length, bool repeated)
MrBedfordVan 0:b9164b348919 73 {
MrBedfordVan 0:b9164b348919 74 int result = I2C::read(address,data,length,repeated);
MrBedfordVan 0:b9164b348919 75
MrBedfordVan 0:b9164b348919 76 //0 indicates a success, presume failure
MrBedfordVan 0:b9164b348919 77 while(result != 0 && retries < MICROBIT_I2C_MAX_RETRIES)
MrBedfordVan 0:b9164b348919 78 {
MrBedfordVan 0:b9164b348919 79 _i2c.i2c->EVENTS_ERROR = 0;
MrBedfordVan 0:b9164b348919 80 _i2c.i2c->ENABLE = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
MrBedfordVan 0:b9164b348919 81 _i2c.i2c->POWER = 0;
MrBedfordVan 0:b9164b348919 82 nrf_delay_us(5);
MrBedfordVan 0:b9164b348919 83 _i2c.i2c->POWER = 1;
MrBedfordVan 0:b9164b348919 84 _i2c.i2c->ENABLE = TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos;
MrBedfordVan 0:b9164b348919 85 twi_master_init_and_clear();
MrBedfordVan 0:b9164b348919 86 result = I2C::read(address,data,length,repeated);
MrBedfordVan 0:b9164b348919 87 retries++;
MrBedfordVan 0:b9164b348919 88 }
MrBedfordVan 0:b9164b348919 89
MrBedfordVan 0:b9164b348919 90 if(result != 0)
MrBedfordVan 0:b9164b348919 91 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 92
MrBedfordVan 0:b9164b348919 93 retries = 0;
MrBedfordVan 0:b9164b348919 94 return MICROBIT_OK;
MrBedfordVan 0:b9164b348919 95 }
MrBedfordVan 0:b9164b348919 96
MrBedfordVan 0:b9164b348919 97 /**
MrBedfordVan 0:b9164b348919 98 * Performs a complete write transaction. The bottom bit of the address is forced to 0 to indicate a write.
MrBedfordVan 0:b9164b348919 99 *
MrBedfordVan 0:b9164b348919 100 * @param address 8-bit I2C slave address [ addr | 0 ]
MrBedfordVan 0:b9164b348919 101 *
MrBedfordVan 0:b9164b348919 102 * @param data A pointer to a byte buffer containing the data to write.
MrBedfordVan 0:b9164b348919 103 *
MrBedfordVan 0:b9164b348919 104 * @param length Number of bytes to write
MrBedfordVan 0:b9164b348919 105 *
MrBedfordVan 0:b9164b348919 106 * @param repeated if true, stop is not sent at the end. Defaults to false.
MrBedfordVan 0:b9164b348919 107 *
MrBedfordVan 0:b9164b348919 108 * @return MICROBIT_OK on success, MICROBIT_I2C_ERROR if an unresolved write failure is detected.
MrBedfordVan 0:b9164b348919 109 */
MrBedfordVan 0:b9164b348919 110 int MicroBitI2C::write(int address, const char *data, int length, bool repeated)
MrBedfordVan 0:b9164b348919 111 {
MrBedfordVan 0:b9164b348919 112 int result = I2C::write(address,data,length,repeated);
MrBedfordVan 0:b9164b348919 113
MrBedfordVan 0:b9164b348919 114 //0 indicates a success, presume failure
MrBedfordVan 0:b9164b348919 115 while(result != 0 && retries < MICROBIT_I2C_MAX_RETRIES)
MrBedfordVan 0:b9164b348919 116 {
MrBedfordVan 0:b9164b348919 117 _i2c.i2c->EVENTS_ERROR = 0;
MrBedfordVan 0:b9164b348919 118 _i2c.i2c->ENABLE = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
MrBedfordVan 0:b9164b348919 119 _i2c.i2c->POWER = 0;
MrBedfordVan 0:b9164b348919 120 nrf_delay_us(5);
MrBedfordVan 0:b9164b348919 121 _i2c.i2c->POWER = 1;
MrBedfordVan 0:b9164b348919 122 _i2c.i2c->ENABLE = TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos;
MrBedfordVan 0:b9164b348919 123
MrBedfordVan 0:b9164b348919 124 twi_master_init_and_clear();
MrBedfordVan 0:b9164b348919 125 result = I2C::write(address,data,length,repeated);
MrBedfordVan 0:b9164b348919 126 retries++;
MrBedfordVan 0:b9164b348919 127 }
MrBedfordVan 0:b9164b348919 128
MrBedfordVan 0:b9164b348919 129 if(result != 0)
MrBedfordVan 0:b9164b348919 130 return MICROBIT_I2C_ERROR;
MrBedfordVan 0:b9164b348919 131
MrBedfordVan 0:b9164b348919 132 retries = 0;
MrBedfordVan 0:b9164b348919 133 return MICROBIT_OK;
MrBedfordVan 0:b9164b348919 134 }