tca9548a.h

00001 /** TCA9548A library
00002  *
00003  * @author Akash Vibhute
00004  * @author < akash . roboticist [at] gmail . com >
00005  * @version 0.1
00006  * @date May/24/2016
00007  *
00008  * @section LICENSE
00009  *
00010  * Copyright (c) 2015 Akash Vibhute
00011  *
00012  * Licensed under the Apache License, Version 2.0 (the "License");
00013  * you may not use this file except in compliance with the License.
00014  * You may obtain a copy of the License at
00015  * http://www.apache.org/licenses/LICENSE-2.0
00016  *
00017  * Unless required by applicable law or agreed to in writing, software
00018  * distributed under the License is distributed on an "AS IS" BASIS,
00019  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00020  * See the License for the specific language governing permissions and
00021  * limitations under the License.
00022  *
00023  * The above copyright notice and this permission notice shall be included in
00024  * all copies or substantial portions of the Software.
00025  *
00026  *
00027  */
00028  
00029 #ifndef TCA9548A_H
00030 #define TCA9548A_H
00031  
00032 #include "mbed.h"
00033  
00034 /** TCA9548A class
00035  *
00036  *  @section DESCRIPTION
00037  *  TCA9548A: Low-Voltage 8-Channel I2C Switch With Reset
00038  *  The TCA9548A device has eight bidirectional translating switches that can be 
00039  *  controlled through the I2C bus. The SCL/SDA upstream pair fans out to eight 
00040  *  downstream pairs, or channels. Any individual SCn/SDn channel or combination 
00041  *  of channels can be selected, determined by the contents of the programmable
00042  *  control register.
00043  *
00044  *  The TCA9548A has a user 8 selectable address in the range 0x70 thru 0x77 (7-bit),
00045  *  based on the configuration of Addr pins (A0, A1, A2). Default address is 0x70 for
00046  *  A0:A2 pull down.
00047  *
00048  *  Datasheet for TCA9548A can be found at:
00049  *  http://www.ti.com/lit/ds/symlink/tca9548a.pdf
00050  *
00051  *  Example:
00052  *  @code
00053  *  #include "mbed.h"
00054  *  #include "LM75B.h"
00055  *  #include "TCA9548A.h"
00056  *  
00057  *  TCA9548A i2c_sw(I2C_SDA, I2C_SCL); //default address 0x70 applied
00058  *  
00059  *  int main()
00060  *  {
00061  *      // By default TCA9548A performs a power on reset and all downstream ports are deselected
00062  *      
00063  *      i2c_sw.select(0);               //  select  the channel 0
00064  *      LM75B tmp0(I2C_SDA, I2C_SCL);   //  making instance after a branch of I2C bus (which is connecting the LM75B) enabled
00065  *  
00066  *      i2c_sw.select(1);               //  select  the channel 1
00067  *      LM75B tmp1(I2C_SDA, I2C_SCL);   //  making instance after a branch of I2C bus (which is connecting the LM75B) enabled
00068  *  
00069  *      while(1) {
00070  *          
00071  *          i2c_sw.select(0);           //  select  the channel 0
00072  *          printf( "%.3f\r\n", tmp0.read() );
00073  *  
00074  *          i2c_sw.select(1);           //  select  the channel 1
00075  *          printf( "%.3f\r\n", tmp1.read() );
00076  *  
00077  *          wait( 1.0 );
00078  *      }
00079  *  }
00080  *  @endcode
00081  */
00082  
00083 class TCA9548A
00084 {
00085 public:
00086  
00087     /** Create a TCA9546A instance connected to specified I2C pins with specified address
00088      *
00089      * @param sda I2C-bus SDA pin
00090      * @param scl I2C-bus SCL pin
00091      * @param i2c_address I2C-bus address (default: 0x70)
00092      * @param reset TCA9546A reset pin (default: NC for simple pullup connected)
00093      * @param hz I2C bus frequency (default: 400kHz)
00094      */
00095     TCA9548A( PinName sda, PinName scl, uint8_t i2c_address = 0x70, PinName resetPin = NC, uint32_t hz = 400000 );
00096  
00097     /** Selecting a channel
00098      *
00099      *  Switch to commended downstream I2C channel
00100      *
00101      * @param channel channel number
00102      */
00103     void select(uint8_t channel);
00104  
00105     /** Reset TCA9546A
00106      *
00107      *  Reset switch
00108      */
00109     void reset();
00110  
00111  
00112 private:
00113     I2C i2c_;
00114     DigitalOut reset_pin;
00115     uint8_t i2c_addr;
00116 
00117 };
00118  
00119 #endif  //  TCA9548A_H