twi_master.cpp

00001 /**
00002  * @brief Implementation of TWI_Master class.
00003  * 
00004  * @file twi_master.cpp
00005  * @author Joel von Rotz
00006  * @date 18.07.2018
00007  */
00008 #include "mbed.h"
00009 #include "twi_master.h "
00010 
00011 /**
00012  * @brief Construct a new TWI_Master object. The given parameters should be all the necessary things to start
00013  * interacting with the other libraries.
00014  * 
00015  * @param sda SDA-Pin
00016  * @param scl SCL-Pin
00017  * @param frequency     I2C-frequency (default: 400kHz)
00018  */
00019 TWI_Master::TWI_Master(PinName sda, PinName scl, uint32_t frequency) : 
00020         m_i2c_sensor(sda, scl)
00021 {
00022     m_i2c_sensor.frequency(frequency);
00023 }
00024 
00025 /**
00026  * @brief Writes data into specified address (changes every bit)
00027  * 
00028  * @param slave_address     register-address which will be written to 
00029  * @param data              8-bit value that overwrites the register-value
00030  */
00031 void        TWI_Master::i2c_write(uint8_t i2c_address, uint8_t slave_address, const uint8_t data)
00032 {
00033     char writeArray[2] = {slave_address, data};
00034     m_i2c_sensor.write(i2c_address, writeArray, 2, false);
00035 }
00036 
00037 /**
00038  * @brief Writes bits by masking the necessary bits. The data variables will be normally masked with the mask 
00039  * <code><strong>(data & mask)</strong></code>, the register will be masked by the inverted mask <code><strong>(register_value & ~mask)</strong></code>.
00040  * What will be written to the register will be <code><strong> new_register_data = (data | register_value) </strong></code>.
00041  * 
00042  * @param slave_address     register-address that will be edited
00043  * @param data              8-bit value that edit the editable bits (which are determined by the mask) 
00044  * @param mask              Bits that want to be changed, all the other bits will be saved. 
00045  */
00046 void        TWI_Master::i2c_writeBits(uint8_t i2c_address, uint8_t slave_address, const uint8_t data, uint8_t mask)
00047 {
00048     char current_value;
00049     char writeArray[2] = {slave_address, data};
00050 
00051     //Get current value of desired register and mask it with mask-value
00052     current_value = i2c_read(i2c_address, slave_address);
00053     current_value &= ~mask;
00054 
00055     //Combine Data with the new data (additionaly masking the data) and send it to the Sensor
00056     writeArray[1] = current_value | (data & mask);
00057 
00058     m_i2c_sensor.write(i2c_address, writeArray, 2, false);
00059 }
00060 
00061 /**
00062  * @brief Reads multiple registers
00063  * 
00064  * @param slave_address     the start register-address
00065  * @param data              array, which the functions saves the data to
00066  * @param length            the length of the read-sequence
00067  */
00068 void        TWI_Master::i2c_readSeries(uint8_t i2c_address, uint8_t slave_address, uint8_t *data, uint8_t length)
00069 {
00070     char *data_array;
00071     data_array = reinterpret_cast<char*>(data);
00072 
00073     const char temp_address = slave_address;
00074 
00075     m_i2c_sensor.write(i2c_address, &temp_address, 1, true);
00076     m_i2c_sensor.read(i2c_address, data_array,length, false);
00077 }
00078 
00079 /**
00080  * @brief Reads one register from the specified register-address.
00081  * 
00082  * @param slave_address     the desired register-address for reading
00083  * @return uint8_t          returns read data
00084  */
00085 uint8_t     TWI_Master::i2c_read(uint8_t i2c_address, uint8_t slave_address)
00086 {
00087     char data;
00088     const char temp_address = slave_address;
00089     m_i2c_sensor.write(i2c_address, &temp_address, 1, true);
00090     m_i2c_sensor.read(i2c_address, &data, 1, false);
00091     return data;
00092 }
00093 
00094 /**
00095  * @brief Reads one register from the specified address and masks it with
00096  * the given mask.
00097  * 
00098  * @param slave_address     the desired register-address for reading
00099  * @param mask              the mask for the desired bits
00100  * @return uint8_t          returns the masked data
00101  */
00102 uint8_t     TWI_Master::i2c_readBits(uint8_t i2c_address, uint8_t slave_address, uint8_t mask)
00103 {
00104     char data;
00105     const char temp_address = slave_address;
00106     m_i2c_sensor.write(i2c_address, &temp_address, 1, true);
00107     m_i2c_sensor.read(i2c_address, &data, 1, false);
00108     return data & mask;
00109 }
00110