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1294中ADC如何知道测的是哪个电压值

1294开发板中ADC测量AIN2的电压,应怎么设置函数?急求解答,谢谢。

  • 您可以参考tivaware内的相关代码

    C:\ti\TivaWare_C_Series-2.1.4.178\examples\peripherals\adc

    //*****************************************************************************
    //
    // single_ended.c - Example demonstrating how to configure the ADC for
    //                  single ended operation.
    //
    // Copyright (c) 2010-2017 Texas Instruments Incorporated.  All rights reserved.
    // Software License Agreement
    // 
    //   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 following disclaimer.
    // 
    //   Redistributions in binary form must reproduce the above copyright
    //   notice, this list of conditions and the following disclaimer in the
    //   documentation and/or other materials provided with the  
    //   distribution.
    // 
    //   Neither the name of Texas Instruments Incorporated nor the names of
    //   its contributors may be used to endorse or promote products derived
    //   from this software without specific prior written permission.
    // 
    // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    // OWNER OR CONTRIBUTORS 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.
    // 
    // This is part of revision 2.1.4.178 of the Tiva Firmware Development Package.
    //
    //*****************************************************************************
    
    #include <stdbool.h>
    #include <stdint.h>
    #include "inc/hw_memmap.h"
    #include "driverlib/adc.h"
    #include "driverlib/gpio.h"
    #include "driverlib/pin_map.h"
    #include "driverlib/sysctl.h"
    #include "driverlib/uart.h"
    #include "utils/uartstdio.h"
    
    //*****************************************************************************
    //
    //! \addtogroup adc_examples_list
    //! <h1>Single Ended ADC (single_ended)</h1>
    //!
    //! This example shows how to setup ADC0 as a single ended input and take a
    //! single sample on AIN0/PE3.
    //!
    //! This example uses the following peripherals and I/O signals.  You must
    //! review these and change as needed for your own board:
    //! - ADC0 peripheral
    //! - GPIO Port E peripheral (for AIN0 pin)
    //! - AIN0 - PE3
    //!
    //! The following UART signals are configured only for displaying console
    //! messages for this example.  These are not required for operation of the
    //! ADC.
    //! - UART0 peripheral
    //! - GPIO Port A peripheral (for UART0 pins)
    //! - UART0RX - PA0
    //! - UART0TX - PA1
    //!
    //! This example uses the following interrupt handlers.  To use this example
    //! in your own application you must add these interrupt handlers to your
    //! vector table.
    //! - None.
    //
    //*****************************************************************************
    
    //*****************************************************************************
    //
    // This function sets up UART0 to be used for a console to display information
    // as the example is running.
    //
    //*****************************************************************************
    void
    InitConsole(void)
    {
        //
        // Enable GPIO port A which is used for UART0 pins.
        // TODO: change this to whichever GPIO port you are using.
        //
        SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
    
        //
        // Configure the pin muxing for UART0 functions on port A0 and A1.
        // This step is not necessary if your part does not support pin muxing.
        // TODO: change this to select the port/pin you are using.
        //
        GPIOPinConfigure(GPIO_PA0_U0RX);
        GPIOPinConfigure(GPIO_PA1_U0TX);
    
        //
        // Enable UART0 so that we can configure the clock.
        //
        SysCtlPeripheralEnable(SYSCTL_PERIPH_UART0);
    
        //
        // Use the internal 16MHz oscillator as the UART clock source.
        //
        UARTClockSourceSet(UART0_BASE, UART_CLOCK_PIOSC);
    
        //
        // Select the alternate (UART) function for these pins.
        // TODO: change this to select the port/pin you are using.
        //
        GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
    
        //
        // Initialize the UART for console I/O.
        //
        UARTStdioConfig(0, 115200, 16000000);
    }
    
    //*****************************************************************************
    //
    // Configure ADC0 for a single-ended input and a single sample.  Once the
    // sample is ready, an interrupt flag will be set.  Using a polling method,
    // the data will be read then displayed on the console via UART0.
    //
    //*****************************************************************************
    int
    main(void)
    {
    #if defined(TARGET_IS_TM4C129_RA0) ||                                         \
        defined(TARGET_IS_TM4C129_RA1) ||                                         \
        defined(TARGET_IS_TM4C129_RA2)
        uint32_t ui32SysClock;
    #endif
    
        //
        // This array is used for storing the data read from the ADC FIFO. It
        // must be as large as the FIFO for the sequencer in use.  This example
        // uses sequence 3 which has a FIFO depth of 1.  If another sequence
        // was used with a deeper FIFO, then the array size must be changed.
        //
        uint32_t pui32ADC0Value[1];
    
        //
        // Set the clocking to run at 20 MHz (200 MHz / 10) using the PLL.  When
        // using the ADC, you must either use the PLL or supply a 16 MHz clock
        // source.
        // TODO: The SYSCTL_XTAL_ value must be changed to match the value of the
        // crystal on your board.
        //
    #if defined(TARGET_IS_TM4C129_RA0) ||                                         \
        defined(TARGET_IS_TM4C129_RA1) ||                                         \
        defined(TARGET_IS_TM4C129_RA2)
        ui32SysClock = SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ |
                                           SYSCTL_OSC_MAIN |
                                           SYSCTL_USE_PLL |
                                           SYSCTL_CFG_VCO_480), 20000000);
    #else
        SysCtlClockSet(SYSCTL_SYSDIV_10 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN |
                       SYSCTL_XTAL_16MHZ);
    #endif
    
        //
        // Set up the serial console to use for displaying messages.  This is
        // just for this example program and is not needed for ADC operation.
        //
        InitConsole();
    
        //
        // Display the setup on the console.
        //
        UARTprintf("ADC ->\n");
        UARTprintf("  Type: Single Ended\n");
        UARTprintf("  Samples: One\n");
        UARTprintf("  Update Rate: 250ms\n");
        UARTprintf("  Input Pin: AIN0/PE3\n\n");
    
        //
        // The ADC0 peripheral must be enabled for use.
        //
        SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
    
        //
        // For this example ADC0 is used with AIN0 on port E7.
        // The actual port and pins used may be different on your part, consult
        // the data sheet for more information.  GPIO port E needs to be enabled
        // so these pins can be used.
        // TODO: change this to whichever GPIO port you are using.
        //
        SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);
    
        //
        // Select the analog ADC function for these pins.
        // Consult the data sheet to see which functions are allocated per pin.
        // TODO: change this to select the port/pin you are using.
        //
        GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_3);
    
        //
        // Enable sample sequence 3 with a processor signal trigger.  Sequence 3
        // will do a single sample when the processor sends a signal to start the
        // conversion.  Each ADC module has 4 programmable sequences, sequence 0
        // to sequence 3.  This example is arbitrarily using sequence 3.
        //
        ADCSequenceConfigure(ADC0_BASE, 3, ADC_TRIGGER_PROCESSOR, 0);
    
        //
        // Configure step 0 on sequence 3.  Sample channel 0 (ADC_CTL_CH0) in
        // single-ended mode (default) and configure the interrupt flag
        // (ADC_CTL_IE) to be set when the sample is done.  Tell the ADC logic
        // that this is the last conversion on sequence 3 (ADC_CTL_END).  Sequence
        // 3 has only one programmable step.  Sequence 1 and 2 have 4 steps, and
        // sequence 0 has 8 programmable steps.  Since we are only doing a single
        // conversion using sequence 3 we will only configure step 0.  For more
        // information on the ADC sequences and steps, reference the datasheet.
        //
        ADCSequenceStepConfigure(ADC0_BASE, 3, 0, ADC_CTL_CH0 | ADC_CTL_IE |
                                 ADC_CTL_END);
    
        //
        // Since sample sequence 3 is now configured, it must be enabled.
        //
        ADCSequenceEnable(ADC0_BASE, 3);
    
        //
        // Clear the interrupt status flag.  This is done to make sure the
        // interrupt flag is cleared before we sample.
        //
        ADCIntClear(ADC0_BASE, 3);
    
        //
        // Sample AIN0 forever.  Display the value on the console.
        //
        while(1)
        {
            //
            // Trigger the ADC conversion.
            //
            ADCProcessorTrigger(ADC0_BASE, 3);
    
            //
            // Wait for conversion to be completed.
            //
            while(!ADCIntStatus(ADC0_BASE, 3, false))
            {
            }
    
            //
            // Clear the ADC interrupt flag.
            //
            ADCIntClear(ADC0_BASE, 3);
    
            //
            // Read ADC Value.
            //
            ADCSequenceDataGet(ADC0_BASE, 3, pui32ADC0Value);
    
            //
            // Display the AIN0 (PE3) digital value on the console.
            //
            UARTprintf("AIN0 = %4d\r", pui32ADC0Value[0]);
    
            //
            // This function provides a means of generating a constant length
            // delay.  The function delay (in cycles) = 3 * parameter.  Delay
            // 250ms arbitrarily.
            //
    #if defined(TARGET_IS_TM4C129_RA0) ||                                         \
        defined(TARGET_IS_TM4C129_RA1) ||                                         \
        defined(TARGET_IS_TM4C129_RA2)
            SysCtlDelay(ui32SysClock / 12);
    #else
            SysCtlDelay(SysCtlClockGet() / 12);
    #endif
        }
    }