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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16 | * http://www.rtems.org/license/LICENSE. |
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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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