mbed library sources
Dependents: frdm_kl05z_gpio_test
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Diff: vendor/NXP/LPC1768/hal/analogin_api.c
- Revision:
- 10:3bc89ef62ce7
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/vendor/NXP/LPC1768/hal/analogin_api.c Fri Jun 14 17:49:17 2013 +0100 @@ -0,0 +1,127 @@ +/* mbed Microcontroller Library + * Copyright (c) 2006-2013 ARM Limited + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +#include "analogin_api.h" + +#include "cmsis.h" +#include "pinmap.h" +#include "error.h" + +#define ANALOGIN_MEDIAN_FILTER 1 + +#define ADC_10BIT_RANGE 0x3FF +#define ADC_12BIT_RANGE 0xFFF + +static inline int div_round_up(int x, int y) { + return (x + (y - 1)) / y; +} + +static const PinMap PinMap_ADC[] = { + {P0_23, ADC0_0, 1}, + {P0_24, ADC0_1, 1}, + {P0_25, ADC0_2, 1}, + {P0_26, ADC0_3, 1}, + {P1_30, ADC0_4, 3}, + {P1_31, ADC0_5, 3}, + {P0_2, ADC0_7, 2}, + {P0_3, ADC0_6, 2}, + {NC, NC, 0} +}; + +#define ADC_RANGE ADC_12BIT_RANGE + +void analogin_init(analogin_t *obj, PinName pin) { + obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC); + if (obj->adc == (uint32_t)NC) { + error("ADC pin mapping failed"); + } + + // ensure power is turned on + LPC_SC->PCONP |= (1 << 12); + + // set PCLK of ADC to /1 + LPC_SC->PCLKSEL0 &= ~(0x3 << 24); + LPC_SC->PCLKSEL0 |= (0x1 << 24); + uint32_t PCLK = SystemCoreClock; + + // calculate minimum clock divider + // clkdiv = divider - 1 + uint32_t MAX_ADC_CLK = 13000000; + uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1; + + // Set the generic software-controlled ADC settings + LPC_ADC->ADCR = (0 << 0) // SEL: 0 = no channels selected + | (clkdiv << 8) // CLKDIV: PCLK max ~= 25MHz, /25 to give safe 1MHz at fastest + | (0 << 16) // BURST: 0 = software control + | (0 << 17) // CLKS: not applicable + | (1 << 21) // PDN: 1 = operational + | (0 << 24) // START: 0 = no start + | (0 << 27); // EDGE: not applicable + + pinmap_pinout(pin, PinMap_ADC); +} + +static inline uint32_t adc_read(analogin_t *obj) { + // Select the appropriate channel and start conversion + LPC_ADC->ADCR &= ~0xFF; + LPC_ADC->ADCR |= 1 << (int)obj->adc; + LPC_ADC->ADCR |= 1 << 24; + + // Repeatedly get the sample data until DONE bit + unsigned int data; + do { + data = LPC_ADC->ADGDR; + } while ((data & ((unsigned int)1 << 31)) == 0); + + // Stop conversion + LPC_ADC->ADCR &= ~(1 << 24); + + return (data >> 4) & ADC_RANGE; // 12 bit +} + +static inline void order(uint32_t *a, uint32_t *b) { + if (*a > *b) { + uint32_t t = *a; + *a = *b; + *b = t; + } +} + +static inline uint32_t adc_read_u32(analogin_t *obj) { + uint32_t value; +#if ANALOGIN_MEDIAN_FILTER + uint32_t v1 = adc_read(obj); + uint32_t v2 = adc_read(obj); + uint32_t v3 = adc_read(obj); + order(&v1, &v2); + order(&v2, &v3); + order(&v1, &v2); + value = v2; +#else + value = adc_read(obj); +#endif + return value; +} + +uint16_t analogin_read_u16(analogin_t *obj) { + uint32_t value = adc_read_u32(obj); + + return (value << 4) | ((value >> 8) & 0x000F); // 12 bit +} + +float analogin_read(analogin_t *obj) { + uint32_t value = adc_read_u32(obj); + return (float)value * (1.0f / (float)ADC_RANGE); +}