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targets/TARGET_Silicon_Labs/TARGET_EFM32/analogout_api.c
- Committer:
- amithy
- Date:
- 2017-11-09
- Revision:
- 178:c26431f84b0d
- Parent:
- 150:02e0a0aed4ec
File content as of revision 178:c26431f84b0d:
/***************************************************************************//** * @file analogout_aoi.c ******************************************************************************* * @section License * <b>(C) Copyright 2015 Silicon Labs, http://www.silabs.com</b> ******************************************************************************* * * SPDX-License-Identifier: Apache-2.0 * * 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 "device.h" #if DEVICE_ANALOGOUT #include "mbed_assert.h" #include "mbed_error.h" #include "analogout_api.h" #include "pinmap.h" #include "pinmap_function.h" #include "PeripheralPins.h" #include "clocking.h" #include "em_dac.h" #include "em_cmu.h" static uint8_t dac_initialized = 0; void analogout_init(dac_t *obj, PinName pin) { /* init in-memory structure */ obj->dac = (DAC_TypeDef *) pinmap_peripheral(pin, PinMap_DAC); MBED_ASSERT((int) obj->dac != NC); obj->channel = pin_location(pin, PinMap_DAC); MBED_ASSERT((int) obj->channel != NC); pin_mode(pin, Disabled); if (!dac_initialized) { /* Initialize the DAC. Will disable both DAC channels, so should only be done once */ /* Use default settings */ CMU_ClockEnable(cmuClock_DAC0, true); DAC_Init_TypeDef init = DAC_INIT_DEFAULT; /* Calculate the DAC clock prescaler value that will result in a DAC clock * close to 500kHz. Second parameter is zero. This uses the current HFPERCLK * frequency instead of setting a new one. */ init.prescale = DAC_PrescaleCalc(500000, REFERENCE_FREQUENCY); /* Set reference voltage to VDD */ init.reference = dacRefVDD; DAC_Init(obj->dac, &init); dac_initialized = 1; } /* Use default channel settings */ DAC_InitChannel_TypeDef initChannel = DAC_INITCHANNEL_DEFAULT; initChannel.enable = true; DAC_InitChannel(obj->dac, &initChannel, obj->channel); } void analogout_free(dac_t *obj) { //Reset channel by re-initializing DAC_InitChannel_TypeDef initChannel = DAC_INITCHANNEL_DEFAULT; initChannel.enable = false; DAC_InitChannel(obj->dac, &initChannel, obj->channel); //Check all channels to see if we can disable the DAC completely if((DAC0->CH0CTRL & DAC_CH0CTRL_EN) == 0 && (DAC0->CH1CTRL & DAC_CH1CTRL_EN) == 0) { CMU_ClockEnable(cmuClock_DAC0, false); dac_initialized = 0; } } static inline void dac_write(dac_t *obj, int value) { switch (obj->channel) { case 0: obj->dac->CH0DATA = value; break; case 1: obj->dac->CH1DATA = value; break; } } static inline int dac_read(dac_t *obj) { switch (obj->channel) { case 0: return obj->dac->CH0DATA; break; case 1: return obj->dac->CH1DATA; break; default: error("AnalogOut pin error. Invalid channel"); return -1; break; } } void analogout_write(dac_t *obj, float value) { /* We multiply the float value with 0xFFF because the DAC has 12-bit resolution. * Ie. accepts values between 0 and 0xFFF (4096). */ dac_write(obj, value*0xFFF); } void analogout_write_u16(dac_t *obj, uint16_t value) { /* The DAC has 12 bit resolution, so we remove the 4 least significant bits */ dac_write(obj, value >> 4); } float analogout_read(dac_t *obj) { /* dac_read returns a number between 0 and 0xFFF. Division gives us a float between 0 and 1 */ return dac_read(obj)/(float)0xFFF; } uint16_t analogout_read_u16(dac_t *obj) { /* dac_read returns a number with 12 significant digits, * so we shift in 0s from right to make it a 16 bit number */ return dac_read(obj) << 4; } #endif