[7b35a36] | 1 | /** |
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| 2 | * @file adc.c |
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| 3 | * |
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| 4 | * @ingroup lpc176x |
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| 5 | * |
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| 6 | * @brief ADC library for the lpc176x bsp. |
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| 7 | */ |
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| 8 | |
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| 9 | /* |
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| 10 | * Copyright (c) 2014 Taller Technologies. |
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| 11 | * |
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| 12 | * @author Diaz Marcos (marcos.diaz@tallertechnologies.com) |
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| 13 | * |
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| 14 | * The license and distribution terms for this file may be |
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| 15 | * found in the file LICENSE in this distribution or at |
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[d4edbdbc] | 16 | * http://www.rtems.org/license/LICENSE. |
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[7b35a36] | 17 | */ |
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| 18 | #include <rtems/status-checks.h> |
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| 19 | #include <bsp/adc.h> |
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| 20 | #include <bsp/adc-defs.h> |
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| 21 | |
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| 22 | static lpc176x_adc_device *const adc_device = AD0_BASE_ADDR; |
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| 23 | |
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| 24 | static const lpc176x_adc_pin_map adc_pinmap[ ADC_DEVICES_COUNT ] = |
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| 25 | { |
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| 26 | { |
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| 27 | .pin_number = 23u, |
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| 28 | .pin_function = LPC176X_PIN_FUNCTION_01 |
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| 29 | }, |
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| 30 | { |
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| 31 | .pin_number = 24u, |
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| 32 | .pin_function = LPC176X_PIN_FUNCTION_01 |
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| 33 | }, |
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| 34 | { |
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| 35 | .pin_number = 25u, |
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| 36 | .pin_function = LPC176X_PIN_FUNCTION_01 |
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| 37 | }, |
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| 38 | { |
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| 39 | .pin_number = 26u, |
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| 40 | .pin_function = LPC176X_PIN_FUNCTION_01 |
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| 41 | }, |
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| 42 | { |
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| 43 | .pin_number = 62u, |
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| 44 | .pin_function = LPC176X_PIN_FUNCTION_11 |
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| 45 | }, |
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| 46 | { |
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| 47 | .pin_number = 63u, |
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| 48 | .pin_function = LPC176X_PIN_FUNCTION_11 |
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| 49 | }, |
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| 50 | { |
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| 51 | .pin_number = 3u, |
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| 52 | .pin_function = LPC176X_PIN_FUNCTION_10 |
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| 53 | }, |
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| 54 | { |
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| 55 | .pin_number = 2u, |
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| 56 | .pin_function = LPC176X_PIN_FUNCTION_10 |
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| 57 | } |
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| 58 | }; |
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| 59 | |
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| 60 | /** |
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| 61 | * @brief Checks for a valid pin number for an ADC |
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| 62 | * |
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| 63 | * @param pin_number The pin to check |
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| 64 | * @param adc_number The returned ADC device corresponding to that pin. |
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| 65 | * |
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| 66 | * @return true if valid, false otherwise. |
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| 67 | */ |
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| 68 | static bool valid_pin_number ( |
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| 69 | const lpc176x_pin_number pin_number, |
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| 70 | lpc176x_adc_number *const adc_number |
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| 71 | ) |
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| 72 | { |
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| 73 | bool found = false; |
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| 74 | lpc176x_adc_number adc_device = ADC_0; |
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| 75 | |
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| 76 | while (!found && (adc_device < ADC_DEVICES_COUNT)) |
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| 77 | { |
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| 78 | if (adc_pinmap[adc_device].pin_number == pin_number) |
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| 79 | { |
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| 80 | *adc_number = adc_device; |
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| 81 | found = true; |
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| 82 | } |
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| 83 | ++adc_device; |
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| 84 | } |
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| 85 | |
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| 86 | return found; |
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| 87 | } |
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| 88 | |
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| 89 | /** |
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| 90 | * @brief Turns on the device and sets its clock divisor. |
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| 91 | * |
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| 92 | */ |
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| 93 | static void turn_on_and_set_clkdiv( void ) |
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| 94 | { |
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| 95 | const uint32_t clkdiv = LPC176X_CCLK / ( LPC176X_PCLKDIV * MAX_ADC_CLK ); |
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| 96 | |
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| 97 | adc_device->ADCR = ADC_CR_PDN | ADC_CR_CLKDIV( clkdiv ); |
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| 98 | } |
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| 99 | |
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| 100 | rtems_status_code adc_open( const lpc176x_pin_number pin_number ) |
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| 101 | { |
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| 102 | rtems_status_code sc = RTEMS_INVALID_NUMBER; |
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| 103 | lpc176x_adc_number adc_number = 0; |
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| 104 | if ( valid_pin_number( pin_number, &adc_number ) ) { |
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| 105 | sc = |
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| 106 | lpc176x_module_enable( LPC176X_MODULE_ADC, LPC176X_MODULE_PCLK_DEFAULT ); |
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| 107 | RTEMS_CHECK_SC( sc, "enable adc module" ); |
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| 108 | |
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| 109 | turn_on_and_set_clkdiv(); |
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| 110 | lpc176x_pin_select( adc_pinmap[ adc_number ].pin_number, |
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| 111 | adc_pinmap[ adc_number ].pin_function ); |
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| 112 | lpc176x_pin_set_mode( adc_pinmap[ adc_number ].pin_number, |
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| 113 | LPC176X_PIN_MODE_NONE ); |
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| 114 | } |
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| 115 | |
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| 116 | return sc; |
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| 117 | } |
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| 118 | |
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| 119 | rtems_status_code adc_close( void ) |
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| 120 | { |
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| 121 | adc_device->ADCR &= ~ADC_CR_PDN; |
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| 122 | |
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| 123 | return lpc176x_module_disable( LPC176X_MODULE_ADC ); |
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| 124 | } |
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| 125 | |
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| 126 | /** |
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| 127 | * @brief Starts the conversion for the given channel. |
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| 128 | * |
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| 129 | * @param number The channel to start the conversion. |
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| 130 | */ |
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| 131 | static inline void start_conversion( const lpc176x_adc_number number ) |
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| 132 | { |
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| 133 | adc_device->ADCR = |
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| 134 | ADC_CR_SEL_SET( adc_device->ADCR, ( 1 << number ) ) | ADC_CR_START_NOW; |
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| 135 | } |
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| 136 | |
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| 137 | /** |
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| 138 | * @brief Stops the conversion. |
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| 139 | * |
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| 140 | */ |
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| 141 | static inline void stop_conversion( void ) |
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| 142 | { |
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| 143 | adc_device->ADCR &= ~ADC_CR_START_NOW; |
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| 144 | } |
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| 145 | |
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| 146 | /** |
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| 147 | * @brief Gets float percentage of the result of a conversion. |
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| 148 | * |
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| 149 | * @param data The result of a conversion. |
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| 150 | * @return A float percentage (between 0.0f and 1.0f). |
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| 151 | */ |
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| 152 | static inline float get_float( const uint32_t data ) |
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| 153 | { |
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| 154 | return ( (float) data / (float) ADC_RANGE ); |
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| 155 | } |
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| 156 | |
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| 157 | |
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| 158 | /** |
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| 159 | * @brief Reads the ADC value for the given ADC number. |
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| 160 | * |
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| 161 | * @param adc_number Which ADC device read. |
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| 162 | * @return The read value. |
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| 163 | */ |
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| 164 | static uint32_t read( const lpc176x_adc_number adc_number ) |
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| 165 | { |
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| 166 | uint32_t data; |
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| 167 | |
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| 168 | start_conversion( adc_number ); |
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| 169 | |
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| 170 | do { |
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| 171 | data = adc_device->ADGDR; |
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| 172 | } while ( !ADC_DATA_CONVERSION_DONE( data ) ); |
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| 173 | |
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| 174 | stop_conversion(); |
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| 175 | |
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| 176 | return ADC_DR_VALUE( data ); |
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| 177 | } |
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| 178 | |
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| 179 | /** |
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| 180 | * @brief Checks if the passed parameters are ordered from lowest |
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| 181 | * to highest. |
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| 182 | * |
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| 183 | * @param a The suggested lowest value. |
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| 184 | * @param b The suggested middle value. |
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| 185 | * @param c The suggested highest value. |
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| 186 | * @return True if it is in the right order, false otherwise. |
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| 187 | */ |
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| 188 | static inline bool lowest_to_highest_ordered( |
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| 189 | const uint32_t a, |
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| 190 | const uint32_t b, |
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| 191 | const uint32_t c |
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| 192 | ) |
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| 193 | { |
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| 194 | return ( ( a <= b ) && ( b <= c ) ); |
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| 195 | } |
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| 196 | |
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| 197 | /** |
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| 198 | * @brief Gets median value from the three passed parameters. |
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| 199 | * |
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| 200 | * @param a The first parameter. |
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| 201 | * @param b The second parameter. |
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| 202 | * @param c The third parameter. |
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| 203 | * |
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| 204 | * @return The median of the three parameters. |
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| 205 | */ |
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| 206 | static uint32_t get_median( |
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| 207 | const uint32_t a, |
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| 208 | const uint32_t b, |
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| 209 | const uint32_t c |
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| 210 | ) |
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| 211 | { |
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| 212 | uint32_t median; |
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| 213 | |
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| 214 | if ( lowest_to_highest_ordered( a, b, c) |
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| 215 | || lowest_to_highest_ordered( c, b, a ) ) { |
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| 216 | median = b; |
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| 217 | } else if ( lowest_to_highest_ordered( b, a, c ) |
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| 218 | || lowest_to_highest_ordered( c, a, b ) ) { |
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| 219 | median = a; |
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| 220 | } else { |
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| 221 | median = c; |
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| 222 | } |
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| 223 | |
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| 224 | return median; |
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| 225 | } |
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| 226 | |
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| 227 | rtems_status_code adc_read( |
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| 228 | const lpc176x_pin_number pin_number , |
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| 229 | float *const result |
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| 230 | ) |
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| 231 | { |
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| 232 | rtems_status_code sc = RTEMS_INVALID_NUMBER; |
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| 233 | lpc176x_adc_number adc_number = 0; |
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| 234 | if ( valid_pin_number( pin_number, &adc_number ) ) { |
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| 235 | const uint32_t first = read( adc_number ); |
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| 236 | const uint32_t second = read( adc_number ); |
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| 237 | const uint32_t third = read( adc_number ); |
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| 238 | const uint32_t median = get_median( first, second, third ); |
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| 239 | *result = get_float( median ); |
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| 240 | sc = RTEMS_SUCCESSFUL; |
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| 241 | } |
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| 242 | |
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| 243 | return sc; |
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| 244 | } |
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