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Dependencies:   mbed FastIO FastPWM USBDevice

Fork of Pinscape_Controller by Mike R

AltAnalogIn/AltAnalogIn.h@43:7a6364d82a41, 2016-02-06 (annotated)

Committer:
mjr
Date:
Sat Feb 06 20:21:48 2016 +0000
Revision:
43:7a6364d82a41
Child:
45:c42166b2878c
Before floating point plunger ranging

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mjr 43:7a6364d82a41 1 #ifndef ALTANALOGIN_H
mjr 43:7a6364d82a41 2 #define ALTANALOGIN_H
mjr 43:7a6364d82a41 3
mjr 43:7a6364d82a41 4 // This is a slightly modified version of Scissors's FastAnalogIn.
mjr 43:7a6364d82a41 5 //
mjr 43:7a6364d82a41 6 // This version is optimized for reading from multiple inputs. The KL25Z has
mjr 43:7a6364d82a41 7 // multiple ADC channels, but the multiplexer hardware only allows sampling one
mjr 43:7a6364d82a41 8 // at a time. The entire sampling process from start to finish is serialized
mjr 43:7a6364d82a41 9 // in the multiplexer, so we unfortunately can't overlap the sampling times
mjr 43:7a6364d82a41 10 // for multiple channels - we have to wait in sequence for the sampling period
mjr 43:7a6364d82a41 11 // on each channel, one after the other.
mjr 43:7a6364d82a41 12 //
mjr 43:7a6364d82a41 13 // The base version of FastAnalogIn uses the hardware's continuous conversion
mjr 43:7a6364d82a41 14 // feature to speed up sampling. When sampling multiple inputs, that feature
mjr 43:7a6364d82a41 15 // becomes useless, and in fact the way FastAnalogIn uses it creates additional
mjr 43:7a6364d82a41 16 // overhead for multiple input sampling. But FastAnalogIn still has some speed
mjr 43:7a6364d82a41 17 // advantages over the base mbed AnalogIn implementation, since it sets all of
mjr 43:7a6364d82a41 18 // the other conversion settings to the fastest options. This version keeps the
mjr 43:7a6364d82a41 19 // other speed-ups from FastAnalogIn, but dispenses with the continuous sampling.
mjr 43:7a6364d82a41 20
mjr 43:7a6364d82a41 21 /*
mjr 43:7a6364d82a41 22 * Includes
mjr 43:7a6364d82a41 23 */
mjr 43:7a6364d82a41 24 #include "mbed.h"
mjr 43:7a6364d82a41 25 #include "pinmap.h"
mjr 43:7a6364d82a41 26
mjr 43:7a6364d82a41 27 #if !defined TARGET_LPC1768 && !defined TARGET_KLXX && !defined TARGET_LPC408X && !defined TARGET_LPC11UXX && !defined TARGET_K20D5M
mjr 43:7a6364d82a41 28 #error "Target not supported"
mjr 43:7a6364d82a41 29 #endif
mjr 43:7a6364d82a41 30
mjr 43:7a6364d82a41 31 /** A class similar to AnalogIn, only faster, for LPC1768, LPC408X and KLxx
mjr 43:7a6364d82a41 32 *
mjr 43:7a6364d82a41 33 * AnalogIn does a single conversion when you read a value (actually several conversions and it takes the median of that).
mjr 43:7a6364d82a41 34 * This library runns the ADC conversion automatically in the background.
mjr 43:7a6364d82a41 35 * When read is called, it immediatly returns the last sampled value.
mjr 43:7a6364d82a41 36 *
mjr 43:7a6364d82a41 37 * LPC1768 / LPC4088
mjr 43:7a6364d82a41 38 * Using more ADC pins in continuous mode will decrease the conversion rate (LPC1768:200kHz/LPC4088:400kHz).
mjr 43:7a6364d82a41 39 * If you need to sample one pin very fast and sometimes also need to do AD conversions on another pin,
mjr 43:7a6364d82a41 40 * you can disable the continuous conversion on that ADC channel and still read its value.
mjr 43:7a6364d82a41 41 *
mjr 43:7a6364d82a41 42 * KLXX
mjr 43:7a6364d82a41 43 * Multiple Fast instances can be declared of which only ONE can be continuous (all others must be non-continuous).
mjr 43:7a6364d82a41 44 *
mjr 43:7a6364d82a41 45 * When continuous conversion is disabled, a read will block until the conversion is complete
mjr 43:7a6364d82a41 46 * (much like the regular AnalogIn library does).
mjr 43:7a6364d82a41 47 * Each ADC channel can be enabled/disabled separately.
mjr 43:7a6364d82a41 48 *
mjr 43:7a6364d82a41 49 * IMPORTANT : It does not play nicely with regular AnalogIn objects, so either use this library or AnalogIn, not both at the same time!!
mjr 43:7a6364d82a41 50 *
mjr 43:7a6364d82a41 51 * Example for the KLxx processors:
mjr 43:7a6364d82a41 52 * @code
mjr 43:7a6364d82a41 53 * // Print messages when the AnalogIn is greater than 50%
mjr 43:7a6364d82a41 54 *
mjr 43:7a6364d82a41 55 * #include "mbed.h"
mjr 43:7a6364d82a41 56 *
mjr 43:7a6364d82a41 57 * AltAnalogIn temperature(PTC2); //Fast continuous sampling on PTC2
mjr 43:7a6364d82a41 58 * AltAnalogIn speed(PTB3, 0); //Fast non-continuous sampling on PTB3
mjr 43:7a6364d82a41 59 *
mjr 43:7a6364d82a41 60 * int main() {
mjr 43:7a6364d82a41 61 * while(1) {
mjr 43:7a6364d82a41 62 * if(temperature > 0.5) {
mjr 43:7a6364d82a41 63 * printf("Too hot! (%f) at speed %f", temperature.read(), speed.read());
mjr 43:7a6364d82a41 64 * }
mjr 43:7a6364d82a41 65 * }
mjr 43:7a6364d82a41 66 * }
mjr 43:7a6364d82a41 67 * @endcode
mjr 43:7a6364d82a41 68 * Example for the LPC1768 processor:
mjr 43:7a6364d82a41 69 * @code
mjr 43:7a6364d82a41 70 * // Print messages when the AnalogIn is greater than 50%
mjr 43:7a6364d82a41 71 *
mjr 43:7a6364d82a41 72 * #include "mbed.h"
mjr 43:7a6364d82a41 73 *
mjr 43:7a6364d82a41 74 * AltAnalogIn temperature(p20);
mjr 43:7a6364d82a41 75 *
mjr 43:7a6364d82a41 76 * int main() {
mjr 43:7a6364d82a41 77 * while(1) {
mjr 43:7a6364d82a41 78 * if(temperature > 0.5) {
mjr 43:7a6364d82a41 79 * printf("Too hot! (%f)", temperature.read());
mjr 43:7a6364d82a41 80 * }
mjr 43:7a6364d82a41 81 * }
mjr 43:7a6364d82a41 82 * }
mjr 43:7a6364d82a41 83 * @endcode
mjr 43:7a6364d82a41 84 */
mjr 43:7a6364d82a41 85 class AltAnalogIn {
mjr 43:7a6364d82a41 86
mjr 43:7a6364d82a41 87 public:
mjr 43:7a6364d82a41 88 /** Create an AltAnalogIn, connected to the specified pin
mjr 43:7a6364d82a41 89 *
mjr 43:7a6364d82a41 90 * @param pin AnalogIn pin to connect to
mjr 43:7a6364d82a41 91 * @param enabled Enable the ADC channel (default = true)
mjr 43:7a6364d82a41 92 */
mjr 43:7a6364d82a41 93 AltAnalogIn( PinName pin, bool enabled = true );
mjr 43:7a6364d82a41 94
mjr 43:7a6364d82a41 95 ~AltAnalogIn( void )
mjr 43:7a6364d82a41 96 {
mjr 43:7a6364d82a41 97 }
mjr 43:7a6364d82a41 98
mjr 43:7a6364d82a41 99 /** Start a sample. This sets the ADC multiplexer to read from
mjr 43:7a6364d82a41 100 * this input and activates the sampler.
mjr 43:7a6364d82a41 101 */
mjr 43:7a6364d82a41 102 inline void start()
mjr 43:7a6364d82a41 103 {
mjr 43:7a6364d82a41 104 // update the MUX bit in the CFG2 register only if necessary
mjr 43:7a6364d82a41 105 static int lastMux = -1;
mjr 43:7a6364d82a41 106 if (lastMux != ADCmux)
mjr 43:7a6364d82a41 107 {
mjr 43:7a6364d82a41 108 // remember the new register value
mjr 43:7a6364d82a41 109 lastMux = ADCmux;
mjr 43:7a6364d82a41 110
mjr 43:7a6364d82a41 111 // select the multiplexer for our ADC channel
mjr 43:7a6364d82a41 112 if (ADCmux)
mjr 43:7a6364d82a41 113 ADC0->CFG2 |= ADC_CFG2_MUXSEL_MASK;
mjr 43:7a6364d82a41 114 else
mjr 43:7a6364d82a41 115 ADC0->CFG2 &= ~ADC_CFG2_MUXSEL_MASK;
mjr 43:7a6364d82a41 116 }
mjr 43:7a6364d82a41 117
mjr 43:7a6364d82a41 118 // select our ADC channel in the control register - this initiates sampling
mjr 43:7a6364d82a41 119 // on the channel
mjr 43:7a6364d82a41 120 ADC0->SC1[0] = startMask;
mjr 43:7a6364d82a41 121 }
mjr 43:7a6364d82a41 122
mjr 43:7a6364d82a41 123
mjr 43:7a6364d82a41 124
mjr 43:7a6364d82a41 125 /** Returns the raw value
mjr 43:7a6364d82a41 126 *
mjr 43:7a6364d82a41 127 * @param return Unsigned integer with converted value
mjr 43:7a6364d82a41 128 */
mjr 43:7a6364d82a41 129 inline uint16_t read_u16()
mjr 43:7a6364d82a41 130 {
mjr 43:7a6364d82a41 131 // wait for the hardware to signal that the sample is completed
mjr 43:7a6364d82a41 132 while ((ADC0->SC1[0] & ADC_SC1_COCO_MASK) == 0);
mjr 43:7a6364d82a41 133
mjr 43:7a6364d82a41 134 // return the result register value
mjr 43:7a6364d82a41 135 return (uint16_t)ADC0->R[0] << 4; // convert 12-bit to 16-bit, padding with zeroes
mjr 43:7a6364d82a41 136 }
mjr 43:7a6364d82a41 137
mjr 43:7a6364d82a41 138 /** Returns the scaled value
mjr 43:7a6364d82a41 139 *
mjr 43:7a6364d82a41 140 * @param return Float with scaled converted value to 0.0-1.0
mjr 43:7a6364d82a41 141 */
mjr 43:7a6364d82a41 142 float read(void)
mjr 43:7a6364d82a41 143 {
mjr 43:7a6364d82a41 144 unsigned short value = read_u16();
mjr 43:7a6364d82a41 145 return value / 65535.0f;
mjr 43:7a6364d82a41 146 }
mjr 43:7a6364d82a41 147
mjr 43:7a6364d82a41 148 /** An operator shorthand for read()
mjr 43:7a6364d82a41 149 */
mjr 43:7a6364d82a41 150 operator float() { return read(); }
mjr 43:7a6364d82a41 151
mjr 43:7a6364d82a41 152
mjr 43:7a6364d82a41 153 private:
mjr 43:7a6364d82a41 154 char ADCnumber; // ADC number of our input pin
mjr 43:7a6364d82a41 155 char ADCmux; // multiplexer for our input pin (0=A, 1=B)
mjr 43:7a6364d82a41 156 uint32_t startMask;
mjr 43:7a6364d82a41 157 };
mjr 43:7a6364d82a41 158
mjr 43:7a6364d82a41 159 #endif