AT91SAM7X之ADC

/* ---------------------------------------------------------------------------- * ATMEL Microcontroller Software Support * ---------------------------------------------------------------------------- * Copyright (c) 2008, Atmel Corporation * * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * - Redistributions of source code must retain the above copyright notice, * this list of conditions and the disclaimer below. * * Atmel's name may not be used to endorse or promote products derived from * this software without specific prior written permission. * * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * ---------------------------------------------------------------------------- */ //------------------------------------------------------------------------------ // Headers //------------------------------------------------------------------------------ #include <board.h> #include <adc/adc.h> #include <utility/trace.h> #include <utility/assert.h> //----------------------------------------------------------------------------- /// Configure the Mode Register of the ADC controller /// \param pAdc Pointer to an AT91S_ADC instance. /// \param mode value to write in mode register //----------------------------------------------------------------------------- static void ADC_CfgModeReg(AT91S_ADC *pAdc, unsigned int mode) { ASSERT((mode&0xF08000C0)== 0, "ADC Bad configuration ADC MR"); // Clear the register pAdc->ADC_MR = 0; // Write to the MR register pAdc->ADC_MR = mode; } //------------------------------------------------------------------------------ // Global Functions //------------------------------------------------------------------------------ //----------------------------------------------------------------------------- /// Initialize the ADC controller /// \param pAdc Pointer to an AT91S_ADC instance. /// \param trgEn trigger mode, software or Hardware /// \param trgSel hardware trigger selection /// \param sleepMode sleep mode selection /// \param resolution resolution selection 8 bits or 10 bits /// \param mckClock value of MCK in Hz /// \param adcClock value of the ADC clock in Hz /// \param startupTime value of the start up time (in 盜) (see datasheet) /// \param sampleAndHoldTime (in ns) //----------------------------------------------------------------------------- void ADC_Initialize (AT91S_ADC *pAdc, unsigned char idAdc, unsigned char trgEn, unsigned char trgSel, unsigned char sleepMode, unsigned char resolution, unsigned int mckClock, unsigned int adcClock, unsigned int startupTime, unsigned int sampleAndHoldTime) { unsigned int prescal; unsigned int startup; unsigned int shtim; ASSERT(startupTime<=ADC_STARTUP_TIME_MAX, "ADC Bad startupTime\n\r"); ASSERT(sampleAndHoldTime>=ADC_TRACK_HOLD_TIME_MIN, "ADC Bad sampleAndHoldTime\n\r"); // Example: // 5 MHz operation, 20盜 startup time, 600ns track and hold time // PRESCAL: Prescaler Rate Selection ADCClock = MCK / ( (PRESCAL+1) * 2 ) // PRESCAL = [MCK / (ADCClock * 2)] -1 = [48/(5*2)]-1 = 3,8 // PRESCAL = 4 -> 48/((4+1)*2) = 48/10 = 4.8MHz // 48/((3+1)*2) = 48/8 = 6MHz // Startup Time = (STARTUP+1) * 8 / ADCClock // STARTUP = [(Startup Time * ADCClock)/8]-1 = [(20 10e-6 * 5000000)/8]-1 = 11,5 // STARTUP = 11 -> (11+1)*8/48000000 = 96/4800000 = 20盜 // // Sample & Hold Time = (SHTIM+1) / ADCClock // SHTIM = (HoldTime * ADCClock)-1 = (600 10e-9 * 5000000)-1 = 2 // SHTIM = 2 -> (2+1)/4800000 = 1/1200000 = 833ns prescal = (mckClock / (2*adcClock)) - 1; startup = ((adcClock/1000000) * startupTime / 8) - 1; shtim = (((adcClock/1000000) * sampleAndHoldTime)/1000) - 1; ASSERT( (prescal<0x3F), "ADC Bad PRESCAL\n\r"); ASSERT(startup<0x7F, "ADC Bad STARTUP\n\r"); ASSERT(shtim<0xF, "ADC Bad SampleAndHoldTime\n\r"); TRACE_DEBUG("adcClock:%d MasterClock:%d\n\r", (mckClock/((prescal+1)*2)), mckClock); TRACE_DEBUG("prescal:0x%X startup:0x%X shtim:0x%X\n\r", prescal, startup, shtim); if( adcClock != (mckClock/((prescal+1)*2)) ) { TRACE_WARNING("User and calculated adcClocks are different : user=%d calc=%d\n\r", adcClock, (mckClock/((prescal+1)*2))); } // Enable peripheral clock AT91C_BASE_PMC->PMC_PCER = 1 << idAdc; // Reset the controller ADC_SoftReset(pAdc); // Write to the MR register ADC_CfgModeReg( pAdc, ( trgEn & AT91C_ADC_TRGEN) | ( trgSel & AT91C_ADC_TRGSEL) | ( resolution & AT91C_ADC_LOWRES) | ( sleepMode & AT91C_ADC_SLEEP) | ( (prescal<<8) & AT91C_ADC_PRESCAL) | ( (startup<<16) & AT91C_ADC_STARTUP) | ( (shtim<<24) & AT91C_ADC_SHTIM) ); } //----------------------------------------------------------------------------- /// Return the Mode Register of the ADC controller value /// \param pAdc Pointer to an AT91S_ADC instance. /// \return ADC Mode register //----------------------------------------------------------------------------- unsigned int ADC_GetModeReg(AT91S_ADC *pAdc) { return pAdc->ADC_MR; } //----------------------------------------------------------------------------- /// Enable Channel /// \param pAdc Pointer to an AT91S_ADC instance. /// \param channel channel to enable //----------------------------------------------------------------------------- void ADC_EnableChannel(AT91S_ADC *pAdc, unsigned int channel) { ASSERT(channel < 8, "ADC Channel not exist"); // Write to the CHER register pAdc->ADC_CHER = (1 << channel); } //----------------------------------------------------------------------------- /// Disable Channel /// \param pAdc Pointer to an AT91S_ADC instance. /// \param channel channel to disable //----------------------------------------------------------------------------- void ADC_DisableChannel (AT91S_ADC *pAdc, unsigned int channel) { ASSERT(channel < 8, "ADC Channel not exist"); // Write to the CHDR register pAdc->ADC_CHDR = (1 << channel); } //----------------------------------------------------------------------------- /// Return chanel status /// \param pAdc Pointer to an AT91S_ADC instance. /// \return ADC Channel Status Register //----------------------------------------------------------------------------- unsigned int ADC_GetChannelStatus(AT91S_ADC *pAdc) { return pAdc->ADC_CHSR; } //----------------------------------------------------------------------------- /// Software request for a analog to digital conversion /// \param pAdc Pointer to an AT91S_ADC instance. //----------------------------------------------------------------------------- void ADC_St