Diff: targets/hal/TARGET_NXP/TARGET_LPC11XX_11CXX/analogin_api.c

Revision:

30:91c1d09ada54

Child:

32:4742f6c694e8

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/hal/TARGET_NXP/TARGET_LPC11XX_11CXX/analogin_api.c	Wed Sep 25 10:30:04 2013 +0100
@@ -0,0 +1,114 @@
+/* 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"
+
+#include "adc_pinmap.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;
+}
+
+#define ADC_RANGE    ADC_10BIT_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");
+        return;
+    }
+    
+    // Power up ADC
+    LPC_SYSCON->PDRUNCFG &= ~ (1 << 4);
+    LPC_SYSCON->SYSAHBCLKCTRL |= ((uint32_t)1 << 13);
+
+    uint32_t offset = (uint32_t)pin & 0xff;
+    __IO uint32_t *reg = (__IO uint32_t*)(LPC_IOCON_BASE + offset);
+
+    // set pin to ADC mode
+    *reg &= ~(1 << 7); // set ADMODE = 0 (analog mode)
+
+    uint32_t PCLK = SystemCoreClock;
+    uint32_t MAX_ADC_CLK = 4500000;
+    uint32_t clkdiv = div_round_up(PCLK, MAX_ADC_CLK) - 1;
+
+    LPC_ADC->CR = (0 << 0)      // no channels selected
+                | (clkdiv << 8) // max of 4.5MHz
+                | (0 << 16)     // BURST = 0, software controlled
+                | ( 0 << 17 );  // CLKS = 0, 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->CR &= ~0xFF;
+    LPC_ADC->CR |= 1 << (int)obj->adc;
+    LPC_ADC->CR |= 1 << 24;
+    
+    // Repeatedly get the sample data until DONE bit
+    unsigned int data;
+    do {
+        data = LPC_ADC->GDR;
+    } while ((data & ((unsigned int)1 << 31)) == 0);
+    
+    // Stop conversion
+    LPC_ADC->CR &= ~(1 << 24);
+    
+    return (data >> 6) & ADC_RANGE; // 10 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 << 6) | ((value >> 4) & 0x003F); // 10 bit
+}
+
+float analogin_read(analogin_t *obj) {
+    uint32_t value = adc_read_u32(obj);
+    return (float)value * (1.0f / (float)ADC_RANGE);
+}