ADC.rar_24位ADC_c8051f350 adc_c8051f350 AD

//----------------------------------------------------------------------------- // F35x_ADC0_Buffered.c //----------------------------------------------------------------------------- // Copyright 2004 Silicon Laboratories, Inc. // // AUTH: BD / PC / BW // LMOD: BW 15 JUL 2004 // DATE: 06 APR 2004 // // This program demonstrates taking measurements using the 24-bit ADC on the // C8051F350/51 devices. // // Input pin configuration shown in ADC0_Init(). // // For a Noise measurement, connect AIN0 and AIN1 to AGND at the terminal // block. Set "USE_FLOAT" to '1', "PRINT_STATISTICS" to '1', // "PRINT_SAMPLES" to '0', and "PRINT_VOLTAGES" to '0'. // // This software configures the ADC to use an external VREF. Therefore, // on the 'F350 target board, J13 and J14 should have their shorting blocks // installed. // // The standard deviation (Sigma) of a sample set is equivalent to the // effective RMS noise of the conversion system. "Sigma", when converted // to Volts, is equivalent to the input-referred noise floor of the // sampling system. // // Typical values of Sigma from the C8051F350 rev B target board with // AIN0 and AIN1 grounded at the terminal block are around 9 to 11 LSBs // in bipolar mode. For a DC measurement, this is equivalent to a Signal- // to-Noise ratio of about 117dB, or about 20 bits of effective dynamic // range. // // 117dB = 20 log10 ( 11 / 2^23) // 20 bits = 117dB / 6dB/bit // // Another parameter of note for integrating converters is the number of // Noise-Free bits. For a Gaussian-distributed noise floor, this number // can be obtained by multiplying Sigma by 6, evaluating the number of // bits required to contain the result, and subtracting this number of // bits from the 24 available bits, as follows: // // 10 LSBs * 6 = 60 LSBs, which can be contained in 6 bits. Noise-free // resolution is 24bits - 6 bits = 18 bits. // // Refer to 'F350 datasheet tables "ADC0 Electrical Characteristics" and // "Absolute Maximum Ratings" for the MIN/MAX voltage range on input pins. // // If using the eval version of the Keil compiler, set "USE_FLOAT" to '0' // and calculate the standard deviation by taking the square root // of "variance". // // Target: C8051F35x // // Tool chain: KEIL C51 // // v1.0 PC 26 MAY 2004 // Initial Revision (Adapted from 'F350 Temp Sensor Demo) // // set USE_FLOAT to '0' to use EVAL version of Keil compiler #define USE_FLOAT 1 #define PRINT_STATISTICS 1 #define PRINT_SAMPLES 0 #define PRINT_VOLTAGES 0 //----------------------------------------------------------------------------- // Includes //----------------------------------------------------------------------------- #include <c8051f350.h> // SFR declarations #include <stdio.h> // Standard I/O Library #include <math.h> //----------------------------------------------------------------------------- // 16-bit SFR Definitions for 'F35x //----------------------------------------------------------------------------- sfr16 DP = 0x82; // data pointer sfr16 TMR3RL = 0x92; // Timer3 reload value sfr16 TMR3 = 0x94; // Timer3 counter sfr16 ADC0DEC = 0x9a; sfr16 TMR2RL = 0xca; // Timer2 reload value sfr16 TMR2 = 0xcc; // Timer2 counter sfr16 PCA0CP0 = 0xe9; // PCA0 Module 1 Capture/Compare sfr16 PCA0CP1 = 0xeb; // PCA0 Module 2 Capture/Compare sfr16 PCA0CP2 = 0xed; // PCA0 Module 2 Capture/Compare sfr16 PCA0 = 0xf9; // PCA0 counter //----------------------------------------------------------------------------- // Global CONSTANTS //----------------------------------------------------------------------------- #define SYSCLK 49000000 // SYSCLK frequency (Hz) #define BAUDRATE 115200 // UART0 Baudrate (bps) #define MDCLK 2457600 // Modulator Clock (Hz) #define OWR 10 // desired Output Word Rate in Hz #define VREF 250L // External VREF (x 10^-2 V) /* #define VREF 243UL // Internal VREF (x 10^-2 V) */ sbit LED0 = P0^6; // LED0='1' means ON sbit LED1 = P0^7; // LED1='1' means ON sbit SW2 = P1^0; // SW2='0' means switch pressed //----------------------------------------------------------------------------- // Function PROTOTYPES //----------------------------------------------------------------------------- void SYSCLK_Init (void); void PORT_Init (void); void ADC0_Init (void); void IDA0_Init (void); void UART0_Init (void); //----------------------------------------------------------------------------- // MAIN Routine //----------------------------------------------------------------------------- void main (void) { volatile long ADC_OutputVal=0; // Concatenated ADC output value long xdata sample_array[128]; unsigned i; long min; long max; long l_temp; long l_average; long l_variance; long l_owr; #if (USE_FLOAT == 1) float temp; float average; float variance; float stdev; float owr; #endif // USE_FLOAT // disable watchdog timer PCA0MD &= ~0x40; // WDTE = 0 (clear watchdog timer // enable) SYSCLK_Init(); // Initialize system clock to 49 MHz PORT_Init(); // Initialize crossbar and GPIO LED0 = 0; LED1 = 0; ADC0_Init(); // Initialize ADC0 UART0_Init(); // Initialize UART0 EA = 1; // enable global interrupts printf("\nMeasurements using the 24-bit ADC in C8051F350\n"); printf("\nCalibrating ...\n"); EIE1 &= ~0x08; // Disable ADC0 interrupts ADC0MD |= 0x01; // Init Internal Full cal while (!AD0CALC); // Wait for calibration complete ADC0MD &= ~0x07; // clear bits (put ADC0 in IDLE // mode) printf("Calibration complete\n\n"); AD0INT = 0; // clear pending sample indication ADC0MD = 0x83; // Start continuous conversions while(1) { // capture 128 samples printf ("Collecting 128 samples...\n"); LED0 = 1; for (i = 0; i < 128; i++) { while(!AD0INT); // wait till conversion complete AD0INT = 0; // clear AD0 interrupt flag // concatenate ADC0 data bytes to form the 24-bit value ADC_OutputVal = (char)ADC0H; ADC_OutputVal <<= 16; ADC_OutputVal += (long)ADC0L + ((long)ADC0M << 8); sample_array[i] = ADC_OutputVal; } LED0 = 0; // calculate mean, min, and max #if (USE_FLOAT == 1) average = 0; #endif // USE_FLOAT l_average = 0L; min = 0x7fffffffL; max = 0x80000000L; for (i = 0; i < 128; i++) { ADC_OutputVal = sample_array[i]; l_average = l_average + ADC_OutputVal; if (ADC_OutputVal < min) min = ADC_OutputVal; if (ADC_OutputVal > max) max = ADC_OutputVal; #if (USE_FLOAT == 1) average = average + (float) ADC_OutputVal; #endif // USE_FLOAT } l_average = l_average / 128; #if (USE_FLOAT == 1) average = average / 128; #endif // USE_FLOAT // calculate variance l_variance = 0L; #if (USE_FLOAT == 1) variance = 0; #endif // USE_FLOAT