analogin_api.c

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 #include "analogin_api.h"
00017 
00018 #if DEVICE_ANALOGIN
00019 
00020 #include "cmsis.h"
00021 #include "pinmap.h"
00022 #include "error.h"
00023 
00024 #define ANALOGIN_MEDIAN_FILTER      1
00025 
00026 #define ADC_10BIT_RANGE             0x3FF
00027 #define ADC_12BIT_RANGE             0xFFF
00028 
00029 static inline int div_round_up(int x, int y) {
00030   return (x + (y - 1)) / y;
00031 }
00032 
00033 #if defined(TARGET_LPC1768) || defined(TARGET_LPC2368)
00034 static const PinMap PinMap_ADC[] = {
00035     {P0_23, ADC0_0, 1},
00036     {P0_24, ADC0_1, 1},
00037     {P0_25, ADC0_2, 1},
00038     {P0_26, ADC0_3, 1},
00039     {P1_30, ADC0_4, 3},
00040     {P1_31, ADC0_5, 3},
00041 #ifdef TARGET_LPC1768
00042     {P0_2,  ADC0_7, 2},
00043     {P0_3,  ADC0_6, 2},
00044 #endif
00045     {NC,    NC,     0}
00046 };
00047 
00048 #if defined(TARGET_LPC2368)
00049 #   define ADC_RANGE    ADC_10BIT_RANGE
00050 #elif defined(TARGET_LPC1768)
00051 #   define ADC_RANGE    ADC_12BIT_RANGE
00052 #endif
00053 
00054 #elif defined(TARGET_LPC11U24)
00055 static const PinMap PinMap_ADC[] = {
00056     {P0_11, ADC0_0, 0x02},
00057     {P0_12, ADC0_1, 0x02},
00058     {P0_13, ADC0_2, 0x02},
00059     {P0_14, ADC0_3, 0x02},
00060     {P0_15, ADC0_4, 0x02},
00061     {P0_16, ADC0_5, 0x01},
00062     {P0_22, ADC0_6, 0x01},
00063     {P0_23, ADC0_7, 0x01},
00064     {NC   , NC    , 0   }
00065 };
00066 
00067 #define LPC_IOCON0_BASE (LPC_IOCON_BASE)
00068 #define LPC_IOCON1_BASE (LPC_IOCON_BASE + 0x60)
00069 
00070 #define ADC_RANGE    ADC_10BIT_RANGE
00071 #endif
00072 
00073 void analogin_init(analogin_t *obj, PinName pin) {
00074     obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
00075     if (obj->adc == (uint32_t)NC) {
00076         error("ADC pin mapping failed");
00077     }
00078 
00079 #if defined(TARGET_LPC1768) || defined(TARGET_LPC2368)
00080     // ensure power is turned on
00081     LPC_SC->PCONP |= (1 << 12);
00082 
00083     // set PCLK of ADC to /1
00084     LPC_SC->PCLKSEL0 &= ~(0x3 << 24);
00085     LPC_SC->PCLKSEL0 |= (0x1 << 24);
00086     uint32_t PCLK = SystemCoreClock ;
00087 
00088     // calculate minimum clock divider
00089     //  clkdiv = divider - 1
00090     uint32_t MAX_ADC_CLK = 13000000;
00091     uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
00092 
00093     // Set the generic software-controlled ADC settings
00094     LPC_ADC->ADCR = (0 << 0)      // SEL: 0 = no channels selected
00095                   | (clkdiv << 8) // CLKDIV: PCLK max ~= 25MHz, /25 to give safe 1MHz at fastest
00096                   | (0 << 16)     // BURST: 0 = software control
00097                   | (0 << 17)     // CLKS: not applicable
00098                   | (1 << 21)     // PDN: 1 = operational
00099                   | (0 << 24)     // START: 0 = no start
00100                   | (0 << 27);    // EDGE: not applicable
00101 
00102 #elif defined(TARGET_LPC11U24)
00103     // Power up ADC
00104     LPC_SYSCON->PDRUNCFG &= ~ (1 << 4);
00105     LPC_SYSCON->SYSAHBCLKCTRL |= ((uint32_t)1 << 13);
00106 
00107     uint32_t pin_number = (uint32_t)pin;
00108     __IO uint32_t *reg = (pin_number < 32) ? (__IO uint32_t*)(LPC_IOCON0_BASE + 4 * pin_number) : (__IO uint32_t*)(LPC_IOCON1_BASE + 4 * (pin_number - 32));
00109 
00110     // set pin to ADC mode
00111     *reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
00112 
00113     uint32_t PCLK = SystemCoreClock ;
00114     uint32_t MAX_ADC_CLK = 4500000;
00115     uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
00116 
00117     LPC_ADC->CR = (0 << 0)      // no channels selected
00118                 | (clkdiv << 8) // max of 4.5MHz
00119                 | (0 << 16)     // BURST = 0, software controlled
00120                 | ( 0 << 17 );  // CLKS = 0, not applicable
00121 #endif
00122     pinmap_pinout(pin, PinMap_ADC);
00123 }
00124 
00125 static inline uint32_t adc_read(analogin_t *obj) {
00126 #if defined(TARGET_LPC1768) || defined(TARGET_LPC2368)
00127     // Select the appropriate channel and start conversion
00128     LPC_ADC->ADCR &= ~0xFF;
00129     LPC_ADC->ADCR |= 1 << (int)obj->adc;
00130     LPC_ADC->ADCR |= 1 << 24;
00131 
00132     // Repeatedly get the sample data until DONE bit
00133     unsigned int data;
00134     do {
00135         data = LPC_ADC->ADGDR;
00136     } while ((data & ((unsigned int)1 << 31)) == 0);
00137 
00138     // Stop conversion
00139     LPC_ADC->ADCR &= ~(1 << 24);
00140 
00141 #elif defined(TARGET_LPC11U24)
00142     // Select the appropriate channel and start conversion
00143     LPC_ADC->CR &= ~0xFF;
00144     LPC_ADC->CR |= 1 << (int)obj->adc;
00145     LPC_ADC->CR |= 1 << 24;
00146 
00147     // Repeatedly get the sample data until DONE bit
00148     unsigned int data;
00149     do {
00150         data = LPC_ADC->GDR;
00151     } while ((data & ((unsigned int)1 << 31)) == 0);
00152 
00153     // Stop conversion
00154     LPC_ADC->CR &= ~(1 << 24);
00155 #endif
00156 
00157 #if defined(TARGET_LPC1768)
00158     return (data >> 4) & ADC_RANGE; // 12 bit
00159 #elif defined(TARGET_LPC2368) || defined (TARGET_LPC11U24)
00160     return (data >> 6) & ADC_RANGE; // 10 bit
00161 #endif
00162 }
00163 
00164 static inline void order(uint32_t *a, uint32_t *b) {
00165     if (*a > *b) {
00166         uint32_t t = *a;
00167         *a = *b;
00168         *b = t;
00169     }
00170 }
00171 
00172 static inline uint32_t adc_read_u32(analogin_t *obj) {
00173     uint32_t value;
00174 #if ANALOGIN_MEDIAN_FILTER
00175     uint32_t v1 = adc_read(obj);
00176     uint32_t v2 = adc_read(obj);
00177     uint32_t v3 = adc_read(obj);
00178     order(&v1, &v2);
00179     order(&v2, &v3);
00180     order(&v1, &v2);
00181     value = v2;
00182 #else
00183     value = adc_read(obj);
00184 #endif
00185     return value;
00186 }
00187 
00188 uint16_t analogin_read_u16(analogin_t *obj) {
00189     uint32_t value = adc_read_u32(obj);
00190 
00191 #if defined(TARGET_LPC1768)
00192     return (value << 4) | ((value >> 8) & 0x000F); // 12 bit
00193 #elif defined(TARGET_LPC2368) || defined(TARGET_LPC11U24)
00194     return (value << 6) | ((value >> 4) & 0x003F); // 10 bit
00195 #endif
00196 }
00197 
00198 float analogin_read(analogin_t *obj) {
00199     uint32_t value = adc_read_u32(obj);
00200     return (float)value * (1.0f / (float)ADC_RANGE);
00201 }
00202 
00203 #endif