I2C.h

00001 /* mbed Microcontroller Library - I2C
00002  * Copyright (c) 2007-2011 ARM Limited. All rights reserved.
00003  */ 
00004  
00005 #ifndef MBED_I2C_H
00006 #define MBED_I2C_H
00007 
00008 #include "device.h"
00009 
00010 #if DEVICE_I2C
00011 
00012 #include "platform.h"
00013 #include "PinNames.h"
00014 #include "PeripheralNames.h"
00015 #include "Base.h"
00016 
00017 namespace mbed {
00018 
00019 /* Class: I2C
00020  *  An I2C Master, used for communicating with I2C slave devices
00021  *
00022  * Example:
00023  * > // Read from I2C slave at address 0x62
00024  * >
00025  * > #include "mbed.h"
00026  * >
00027  * > I2C i2c(p28, p27);
00028  * >
00029  * > int main() {
00030  * >     int address = 0x62;
00031  * >     char data[2];
00032  * >     i2c.read(address, data, 2);
00033  * > }
00034  */
00035 class I2C : public Base {
00036 
00037 public:
00038 
00039     enum RxStatus {
00040         NoData
00041         , MasterGeneralCall
00042         , MasterWrite
00043         , MasterRead
00044     };
00045 
00046     enum Acknowledge {
00047           NoACK = 0
00048         , ACK   = 1
00049     };
00050 
00051     /* Constructor: I2C
00052      *  Create an I2C Master interface, connected to the specified pins
00053      *
00054      * Variables:
00055      *  sda - I2C data line pin
00056      *  scl - I2C clock line pin
00057      */
00058     I2C(PinName sda, PinName scl, const char *name = NULL);
00059 
00060     /* Function: frequency
00061      *  Set the frequency of the I2C interface
00062      *
00063      * Variables:
00064      *  hz - The bus frequency in hertz
00065      */
00066     void frequency(int hz);
00067 
00068     /* Function: read
00069      *  Read from an I2C slave
00070      *
00071      * Performs a complete read transaction. The bottom bit of
00072      * the address is forced to 1 to indicate a read.
00073      *
00074      * Variables:
00075      *  address - 8-bit I2C slave address [ addr | 1 ]
00076      *  data - Pointer to the byte-array to read data in to 
00077      *  length - Number of bytes to read
00078      *  repeated - Repeated start, true - don't send stop at end
00079      *  returns - 0 on success (ack), or non-0 on failure (nack)
00080      */ 
00081     int read(int address, char *data, int length, bool repeated = false); 
00082 
00083     /* Function: read
00084      *  Read a single byte from the I2C bus
00085      *
00086      * Variables:
00087      *  ack - indicates if the byte is to be acknowledged (1 = acknowledge)
00088      *  returns - the byte read
00089      */
00090     int read(int ack);
00091 
00092     /* Function: write
00093      *  Write to an I2C slave
00094      *
00095      * Performs a complete write transaction. The bottom bit of
00096      * the address is forced to 0 to indicate a write.
00097      *
00098      * Variables:
00099      *  address - 8-bit I2C slave address [ addr | 0 ]
00100      *  data - Pointer to the byte-array data to send 
00101      *  length - Number of bytes to send
00102      *  repeated - Repeated start, true - do not send stop at end
00103      *  returns - 0 on success (ack), or non-0 on failure (nack)
00104      */ 
00105     int write(int address, const char *data, int length, bool repeated = false);
00106 
00107     /* Function: write
00108      *  Write single byte out on the I2C bus
00109      *
00110      * Variables:
00111      *  data - data to write out on bus
00112      *  returns - a '1' if an ACK was received, a '0' otherwise
00113      */
00114     int write(int data);
00115 
00116     /* Function: start
00117      *  Creates a start condition on the I2C bus
00118      */
00119 
00120     void start(void);
00121 
00122     /* Function: stop
00123      *  Creates a stop condition on the I2C bus
00124      */
00125     void stop(void);
00126 
00127 protected:
00128 
00129     void aquire();
00130 
00131     I2CName     _i2c;
00132     static I2C  *_owner;
00133     int         _hz;
00134 
00135 };
00136 
00137 } // namespace mbed
00138 
00139 #endif
00140 
00141 #endif
00142