tool/mbed/mbed-sdk/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC43XX/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  * Ported to NXP LPC43XX by Micromint USA <support@micromint.com>
  17  */
  18 #include "mbed_assert.h"
  19 #include "analogout_api.h"
  20
  21 #include "cmsis.h"
  22 #include "pinmap.h"
  23 #include "mbed_error.h"
  24 #include "gpio_api.h"
  25
  26 static const PinMap PinMap_DAC[] = {
  27 #ifdef TARGET_LPC4337
  28     {P4_3, DAC_0, 0},
  29 #else
  30     {P4_4, DAC_0, 0},
  31 #endif
  32     {NC,   NC,    0}
  33 };
  34
  35 void analogout_init(dac_t *obj, PinName pin) {
  36     obj->dac = (DACName)pinmap_peripheral(pin, PinMap_DAC);
  37     MBED_ASSERT(obj->dac != (DACName)NC);
  38
  39     // Reset pin function to GPIO
  40     gpio_set(pin);
  41     // Select DAC on analog function select register in SCU
  42     LPC_SCU->ENAIO[2] |= 1; // Sets pin as DAC
  43
  44     // Set bias=0 for maximum DAC update rate (1 MHz)
  45     LPC_DAC->CR &= ~DAC_BIAS_EN;
  46     // Enable DAC and DMA
  47     LPC_DAC->CTRL |= DAC_DMA_ENA;
  48
  49     analogout_write_u16(obj, 0);
  50 }
  51
  52 void analogout_free(dac_t *obj) {}
  53
  54 static inline void dac_write(int value) {
  55
  56     // Set the DAC output
  57     LPC_DAC->CR = DAC_SET(value);
  58 }
  59
  60 static inline int dac_read() {
  61     return (DAC_GET(LPC_DAC->CR));
  62 }
  63
  64 void analogout_write(dac_t *obj, float value) {
  65     if (value < 0.0f) {
  66         dac_write(0);
  67     } else if (value > 1.0f) {
  68         dac_write(DAC_RANGE);
  69     } else {
  70         dac_write(value * (float)DAC_RANGE);
  71     }
  72 }
  73
  74 void analogout_write_u16(dac_t *obj, uint16_t value) {
  75     dac_write(value >> 6); // 10-bit
  76 }
  77
  78 float analogout_read(dac_t *obj) {
  79     uint32_t value = dac_read();
  80     return (float)value * (1.0f / (float)DAC_RANGE);
  81 }
  82
  83 uint16_t analogout_read_u16(dac_t *obj) {
  84     uint32_t value = dac_read(); // 10-bit
  85     return (value << 6) | ((value >> 4) & 0x003F);
  86 }