analogout_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 "analogout_api.h"
00017 
00018 #include "cmsis.h"
00019 #include "pinmap.h"
00020 #include "error.h"
00021 
00022 #define RANGE_12BIT     0xFFF
00023 
00024 static const PinMap PinMap_DAC[] = {
00025     {PTE30, DAC_0, 0},
00026     {NC   , NC   , 0}
00027 };
00028 
00029 void analogout_init(dac_t *obj, PinName pin) {
00030     obj->dac = (DACName)pinmap_peripheral(pin, PinMap_DAC);
00031     if (obj->dac == (uint32_t)NC) {
00032         error("DAC pin mapping failed");
00033     }
00034 
00035     SIM->SCGC6 |= SIM_SCGC6_DAC0_MASK;
00036 
00037     uint32_t port = (uint32_t)pin >> PORT_SHIFT;
00038     SIM->SCGC5 |= 1 << (SIM_SCGC5_PORTA_SHIFT + port);
00039 
00040     DAC0->DAT[obj->dac].DATH = 0;
00041     DAC0->DAT[obj->dac].DATL = 0;
00042 
00043     DAC0->C1 = DAC_C1_DACBFMD_MASK;     // One-Time Scan Mode
00044 
00045     DAC0->C0 = DAC_C0_DACEN_MASK        // Enable
00046              | DAC_C0_DACSWTRG_MASK;    // Software Trigger
00047 
00048     pinmap_pinout(pin, PinMap_DAC);
00049 
00050     analogout_write_u16(obj, 0);
00051 }
00052 
00053 void analogout_free(dac_t *obj) {}
00054 
00055 static inline void dac_write(dac_t *obj, int value) {
00056     DAC0->DAT[obj->dac].DATL = (uint8_t)( value       & 0xFF);
00057     DAC0->DAT[obj->dac].DATH = (uint8_t)((value >> 8) & 0xFF);
00058 }
00059 
00060 static inline int dac_read(dac_t *obj) {
00061     return ((DAC0->DAT[obj->dac].DATH << 8) | DAC0->DAT[obj->dac].DATL);
00062 }
00063 
00064 void analogout_write(dac_t *obj, float value) {
00065     if (value < 0.0) {
00066         dac_write(obj, 0);
00067     } else if (value > 1.0) {
00068         dac_write(obj, RANGE_12BIT);
00069     } else {
00070         dac_write(obj, value * (float)RANGE_12BIT);
00071     }
00072 }
00073 
00074 void analogout_write_u16(dac_t *obj, uint16_t value) {
00075     dac_write(obj, value >> 4); // 12-bit
00076 }
00077 
00078 float analogout_read(dac_t *obj) {
00079     uint32_t value = dac_read(obj);
00080     return (float)value * (1.0f / (float)RANGE_12BIT);
00081 }
00082 
00083 uint16_t analogout_read_u16(dac_t *obj) {
00084     uint32_t value = dac_read(obj); // 12-bit
00085     return (value << 4) | ((value >> 8) & 0x003F);
00086 }