FastAnalogIn.h

00001 #ifndef FASTANALOGIN_H
00002 #define FASTANALOGIN_H
00003 
00004 /*
00005  * Includes
00006  */
00007 #include "mbed.h"
00008 #include "pinmap.h"
00009 
00010 #if !defined TARGET_LPC1768 && !defined TARGET_KLXX && !defined TARGET_LPC408X && !defined TARGET_LPC11UXX && !defined TARGET_K20D5M && !defined TARGET_LPC11XX
00011     #error "Target not supported"
00012 #endif
00013 
00014  /** A class similar to AnalogIn, only faster, for LPC1768, LPC408X and KLxx
00015  *
00016  * AnalogIn does a single conversion when you read a value (actually several conversions and it takes the median of that).
00017  * This library runns the ADC conversion automatically in the background.
00018  * When read is called, it immediatly returns the last sampled value.
00019  *
00020  * LPC1768 / LPC4088
00021  * Using more ADC pins in continuous mode will decrease the conversion rate (LPC1768:200kHz/LPC4088:400kHz).
00022  * If you need to sample one pin very fast and sometimes also need to do AD conversions on another pin,
00023  * you can disable the continuous conversion on that ADC channel and still read its value.
00024  *
00025  * KLXX
00026  * Multiple Fast instances can be declared of which only ONE can be continuous (all others must be non-continuous).
00027  *
00028  * When continuous conversion is disabled, a read will block until the conversion is complete
00029  * (much like the regular AnalogIn library does).
00030  * Each ADC channel can be enabled/disabled separately.
00031  *
00032  * IMPORTANT : It does not play nicely with regular AnalogIn objects, so either use this library or AnalogIn, not both at the same time!!
00033  *
00034  * Example for the KLxx processors:
00035  * @code
00036  * // Print messages when the AnalogIn is greater than 50%
00037  *
00038  * #include "mbed.h"
00039  *
00040  * FastAnalogIn temperature(PTC2); //Fast continuous sampling on PTC2
00041  * FastAnalogIn speed(PTB3, 0);    //Fast non-continuous sampling on PTB3
00042  *
00043  * int main() {
00044  *     while(1) {
00045  *         if(temperature > 0.5) {
00046  *             printf("Too hot! (%f) at speed %f", temperature.read(), speed.read());
00047  *         }
00048  *     }
00049  * }
00050  * @endcode
00051  * Example for the LPC1768 processor:
00052  * @code
00053  * // Print messages when the AnalogIn is greater than 50%
00054  *
00055  * #include "mbed.h"
00056  *
00057  * FastAnalogIn temperature(p20);
00058  *
00059  * int main() {
00060  *     while(1) {
00061  *         if(temperature > 0.5) {
00062  *             printf("Too hot! (%f)", temperature.read());
00063  *         }
00064  *     }
00065  * }
00066  * @endcode
00067 */
00068 class FastAnalogIn {
00069 
00070 public:
00071      /** Create a FastAnalogIn, connected to the specified pin
00072      *
00073      * @param pin AnalogIn pin to connect to
00074      * @param enabled Enable the ADC channel (default = true)
00075      */
00076     FastAnalogIn( PinName pin, bool enabled = true );
00077     
00078     ~FastAnalogIn( void )
00079     {
00080         disable();
00081     }
00082     
00083     /** Enable the ADC channel
00084     *
00085     * @param enabled Bool that is true for enable, false is equivalent to calling disable
00086     */
00087     void enable(bool enabled = true);
00088     
00089     /** Disable the ADC channel
00090     *
00091     * Disabling unused channels speeds up conversion in used channels. 
00092     * When disabled you can still call read, that will do a single conversion (actually two since the first one always returns 0 for unknown reason).
00093     * Then the function blocks until the value is read. This is handy when you sometimes needs a single conversion besides the automatic conversion
00094     */
00095     void disable( void );
00096     
00097     /** Returns the raw value
00098     *
00099     * @param return Unsigned integer with converted value
00100     */
00101     unsigned short read_u16( void );
00102     
00103     /** Returns the scaled value
00104     *
00105     * @param return Float with scaled converted value to 0.0-1.0
00106     */
00107     float read( void )
00108     {
00109         unsigned short value = read_u16();
00110         return (float)value * (1.0f/65535.0f);
00111     }
00112     
00113     /** An operator shorthand for read()
00114     */
00115     operator float() {
00116         return read();
00117     }
00118 
00119     
00120 private:
00121     bool running;    
00122     char ADCnumber;
00123     volatile uint32_t *datareg;
00124 };
00125 
00126 #endif