tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC408X/analogout_api.c

   1 /* mbed Microcontroller Library
   2  * Copyright (c) 2006-2013 ARM Limited
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 #include "mbed_assert.h"
  17 #include "analogout_api.h"
  18 #include "cmsis.h"
  19 #include "pinmap.h"
  20
  21 static const PinMap PinMap_DAC[] = {
  22     {P0_26, DAC_0, 2},
  23     {NC   , NC   , 0}
  24 };
  25
  26 void analogout_init(dac_t *obj, PinName pin) {
  27     obj->dac = (DACName)pinmap_peripheral(pin, PinMap_DAC);
  28     MBED_ASSERT(obj->dac != (DACName)NC);
  29
  30     // DAC enable bit must be set
  31     LPC_IOCON->P0_26 |= (1 << 16); // DACEN
  32
  33     // map out (must be done before accessing registers)
  34     pinmap_pinout(pin, PinMap_DAC);
  35
  36     analogout_write_u16(obj, 0);
  37 }
  38
  39 void analogout_free(dac_t *obj) {}
  40
  41 static inline void dac_write(int value) {
  42     value &= 0x3FF; // 10-bit
  43
  44     // Set the DAC output
  45     LPC_DAC->CR = (0 << 16)       // bias = 0
  46                 | (value << 6);
  47 }
  48
  49 static inline int dac_read() {
  50     return (LPC_DAC->CR >> 6) & 0x3FF;
  51 }
  52
  53 void analogout_write(dac_t *obj, float value) {
  54     if (value < 0.0f) {
  55         dac_write(0);
  56     } else if (value > 1.0f) {
  57         dac_write(0x3FF);
  58     } else {
  59         dac_write(value * (float)0x3FF);
  60     }
  61 }
  62
  63 void analogout_write_u16(dac_t *obj, uint16_t value) {
  64     dac_write(value >> 6); // 10-bit
  65 }
  66
  67 float analogout_read(dac_t *obj) {
  68     uint32_t value = dac_read();
  69     return (float)value * (1.0f / (float)0x3FF);
  70 }
  71
  72 uint16_t analogout_read_u16(dac_t *obj) {
  73     uint32_t value = dac_read(); // 10-bit
  74     return (value << 6) | ((value >> 4) & 0x003F);
  75 }