241 lines
8.7 KiB
C
241 lines
8.7 KiB
C
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/**************************************************************************************************
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Filename: hal_adc.c
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Revised: $Date: 2010-03-12 16:10:36 -0800 (Fri, 12 Mar 2010) $
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Revision: $Revision: 21910 $
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Description: This file contains the interface to the HAL ADC.
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Copyright 2006-2010 Texas Instruments Incorporated. All rights reserved.
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IMPORTANT: Your use of this Software is limited to those specific rights
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granted under the terms of a software license agreement between the user
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who downloaded the software, his/her employer (which must be your employer)
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and Texas Instruments Incorporated (the "License"). You may not use this
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Software unless you agree to abide by the terms of the License. The License
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limits your use, and you acknowledge, that the Software may not be modified,
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copied or distributed unless embedded on a Texas Instruments microcontroller
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or used solely and exclusively in conjunction with a Texas Instruments radio
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frequency transceiver, which is integrated into your product. Other than for
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the foregoing purpose, you may not use, reproduce, copy, prepare derivative
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works of, modify, distribute, perform, display or sell this Software and/or
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its documentation for any purpose.
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YOU FURTHER ACKNOWLEDGE AND AGREE THAT THE SOFTWARE AND DOCUMENTATION ARE
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PROVIDED <EFBFBD>AS IS<EFBFBD> WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED,
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INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY, TITLE,
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NON-INFRINGEMENT AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL
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TEXAS INSTRUMENTS OR ITS LICENSORS BE LIABLE OR OBLIGATED UNDER CONTRACT,
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NEGLIGENCE, STRICT LIABILITY, CONTRIBUTION, BREACH OF WARRANTY, OR OTHER
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LEGAL EQUITABLE THEORY ANY DIRECT OR INDIRECT DAMAGES OR EXPENSES
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INCLUDING BUT NOT LIMITED TO ANY INCIDENTAL, SPECIAL, INDIRECT, PUNITIVE
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OR CONSEQUENTIAL DAMAGES, LOST PROFITS OR LOST DATA, COST OF PROCUREMENT
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OF SUBSTITUTE GOODS, TECHNOLOGY, SERVICES, OR ANY CLAIMS BY THIRD PARTIES
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(INCLUDING BUT NOT LIMITED TO ANY DEFENSE THEREOF), OR OTHER SIMILAR COSTS.
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Should you have any questions regarding your right to use this Software,
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contact Texas Instruments Incorporated at www.TI.com.
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**************************************************************************************************/
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/**************************************************************************************************
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* INCLUDES
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**************************************************************************************************/
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#include "hal_adc.h"
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#include "hal_defs.h"
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#include "hal_mcu.h"
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#include "hal_types.h"
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/**************************************************************************************************
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* CONSTANTS
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**************************************************************************************************/
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#define HAL_ADC_EOC 0x80 /* End of Conversion bit */
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#define HAL_ADC_START 0x40 /* Starts Conversion */
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#define HAL_ADC_STSEL_EXT 0x00 /* External Trigger */
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#define HAL_ADC_STSEL_FULL 0x10 /* Full Speed, No Trigger */
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#define HAL_ADC_STSEL_T1C0 0x20 /* Timer1, Channel 0 Compare Event Trigger */
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#define HAL_ADC_STSEL_ST 0x30 /* ADCCON1.ST =1 Trigger */
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#define HAL_ADC_RAND_NORM 0x00 /* Normal Operation */
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#define HAL_ADC_RAND_LFSR 0x04 /* Clock LFSR */
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#define HAL_ADC_RAND_SEED 0x08 /* Seed Modulator */
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#define HAL_ADC_RAND_STOP 0x0c /* Stop Random Generator */
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#define HAL_ADC_RAND_BITS 0x0c /* Bits [3:2] */
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#define HAL_ADC_DEC_064 0x00 /* Decimate by 64 : 8-bit resolution */
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#define HAL_ADC_DEC_128 0x10 /* Decimate by 128 : 10-bit resolution */
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#define HAL_ADC_DEC_256 0x20 /* Decimate by 256 : 12-bit resolution */
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#define HAL_ADC_DEC_512 0x30 /* Decimate by 512 : 14-bit resolution */
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#define HAL_ADC_DEC_BITS 0x30 /* Bits [5:4] */
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#define HAL_ADC_STSEL HAL_ADC_STSEL_ST
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#define HAL_ADC_RAND_GEN HAL_ADC_RAND_STOP
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#define HAL_ADC_REF_VOLT HAL_ADC_REF_AVDD
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#define HAL_ADC_DEC_RATE HAL_ADC_DEC_064
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#define HAL_ADC_SCHN HAL_ADC_CHN_VDD3
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#define HAL_ADC_ECHN HAL_ADC_CHN_GND
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/* ------------------------------------------------------------------------------------------------
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* Local Variables
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* ------------------------------------------------------------------------------------------------
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*/
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#if (HAL_ADC == TRUE)
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static uint8 adcRef;
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#endif
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/**************************************************************************************************
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* @fn HalAdcInit
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*
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* @brief Initialize ADC Service
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*
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* @param None
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*
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* @return None
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**************************************************************************************************/
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void HalAdcInit (void)
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{
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#if (HAL_ADC == TRUE)
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adcRef = HAL_ADC_REF_VOLT;
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#endif
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}
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/**************************************************************************************************
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* @fn HalAdcRead
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*
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* @brief Read the ADC based on given channel and resolution
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*
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* @param channel - channel where ADC will be read
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* @param resolution - the resolution of the value
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*
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* @return 16 bit value of the ADC in offset binary format.
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*
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* Note that the ADC is "bipolar", which means the GND (0V) level is mid-scale.
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* Note2: This function assumes that ADCCON3 contains the voltage reference.
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**************************************************************************************************/
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uint16 HalAdcRead (uint8 channel, uint8 resolution)
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{
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int16 reading = 0;
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#if (HAL_ADC == TRUE)
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uint8 i, resbits;
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uint8 adcChannel = 1;
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/*
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* If Analog input channel is AIN0..AIN7, make sure corresponing P0 I/O pin is enabled. The code
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* does NOT disable the pin at the end of this function. I think it is better to leave the pin
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* enabled because the results will be more accurate. Because of the inherent capacitance on the
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* pin, it takes time for the voltage on the pin to charge up to its steady-state level. If
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* HalAdcRead() has to turn on the pin for every conversion, the results may show a lower voltage
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* than actuality because the pin did not have time to fully charge.
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*/
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if (channel < 8)
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{
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for (i=0; i < channel; i++)
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{
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adcChannel <<= 1;
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}
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}
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/* Enable channel */
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ADCCFG |= adcChannel;
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/* Convert resolution to decimation rate */
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switch (resolution)
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{
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case HAL_ADC_RESOLUTION_8:
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resbits = HAL_ADC_DEC_064;
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break;
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case HAL_ADC_RESOLUTION_10:
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resbits = HAL_ADC_DEC_128;
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break;
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case HAL_ADC_RESOLUTION_12:
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resbits = HAL_ADC_DEC_256;
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break;
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case HAL_ADC_RESOLUTION_14:
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default:
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resbits = HAL_ADC_DEC_512;
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break;
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}
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/* writing to this register starts the extra conversion */
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ADCCON3 = channel | resbits | adcRef;
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/* Wait for the conversion to be done */
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while (!(ADCCON1 & HAL_ADC_EOC));
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/* Disable channel after done conversion */
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ADCCFG &= (adcChannel ^ 0xFF);
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/* Read the result */
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reading = (int16) (ADCL);
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reading |= (int16) (ADCH << 8);
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/* Treat small negative as 0 */
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if (reading < 0)
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reading = 0;
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switch (resolution)
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{
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case HAL_ADC_RESOLUTION_8:
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reading >>= 8;
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break;
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case HAL_ADC_RESOLUTION_10:
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reading >>= 6;
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break;
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case HAL_ADC_RESOLUTION_12:
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reading >>= 4;
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break;
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case HAL_ADC_RESOLUTION_14:
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default:
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reading >>= 2;
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break;
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}
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#else
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// unused arguments
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(void) channel;
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(void) resolution;
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#endif
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return ((uint16)reading);
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}
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/**************************************************************************************************
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* @fn HalAdcSetReference
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*
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* @brief Sets the reference voltage for the ADC and initializes the service
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*
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* @param reference - the reference voltage to be used by the ADC
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*
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* @return none
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*
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**************************************************************************************************/
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void HalAdcSetReference ( uint8 reference )
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{
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#if (HAL_ADC == TRUE)
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adcRef = reference;
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#endif
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}
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/*********************************************************************
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* @fn HalAdcCheckVdd
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*
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* @brief Check for minimum Vdd specified.
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*
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* @param vdd - The board-specific Vdd reading to check for.
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*
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* @return TRUE if the Vdd measured is greater than the 'vdd' minimum parameter;
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* FALSE if not.
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*
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*********************************************************************/
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bool HalAdcCheckVdd(uint8 vdd)
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{
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ADCCON3 = 0x0F;
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while (!(ADCCON1 & 0x80));
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return (ADCH > vdd);
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}
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/**************************************************************************************************
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**************************************************************************************************/
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