基于c8051的adc转换程序

//----------------------------------------------------------------------------- // F12x_ADC0_ExternalInput.c //----------------------------------------------------------------------------- // Program Description: // // This program measures the voltage on an external ADC input and prints the // result to a terminal window via the UART. // // The system is clocked using the internal 24.5MHz oscillator multiplied // up to 49MHz by the on-chip PLL. Results are printed to the UART from a loop // with the rate set by a delay based on Timer 2. This loop periodically reads // the ADC value from a global variable, Result. // // The ADC makes repeated measurements at a rate determined by SAMPLE_RATE using // Timer 3. The end of each ADC conversion initiates an interrupt which calls an // averaging function. <INT_DEC> samples are averaged then the Result value updated. // // For each power of 4 of <INT_DEC>, you gain 1 bit of effective resolution. // For example, <INT_DEC> = 256 gain you 4 bits of resolution: 4^4 = 256. // // The ADC input multiplexer is set for a single-ended input at AIN0.1. The input // amplifier is set for unity gain so a voltage range of 0 to Vref (2.43V) may // be measured. Although voltages up to Vdd may be applied without damaging the // device, only the range 0 to Vref may be measured by the ADC. // The input is available at the 8-position board-edge connector, J20, on the // C8051FX20-TB. // // A 100kohm potentiometer may be connected as a voltage divider between // VREF and AGND as shown below: // // --------- // | // 8 o| AGND ----| // o| VREF ----|<-| // o| AIN0.1 | | // o| | | // o| -------- // o| // o| // 1 o| // | //---------- // // How To Test: // // 1) Download code to a 'F12x device that is connected to a UART transceiver // 2) Connect serial cable from the transceiver to a PC // 3) On the PC, open HyperTerminal (or any other terminal program) and connect // to the COM port at <BAUDRATE> and 8-N-1 // 4) Connect a variable voltage source (between 0 and Vref) // to AIN 0.1, or a potentiometer voltage divider as shown above. // 5) HyperTerminal will print the voltage measured by the device if // everything is working properly //----------------------------------------------------------------------------- // Includes //----------------------------------------------------------------------------- #include <c8051f120.h> // SFR declarations #include <stdio.h> //----------------------------------------------------------------------------- // 16-bit SFR Definitions for 'F12x //----------------------------------------------------------------------------- sfr16 ADC0 = 0xbe; // ADC0 data sfr16 RCAP2 = 0xca; // Timer2 capture/reload sfr16 RCAP3 = 0xca; // Timer3 capture/reload sfr16 TMR2 = 0xcc; // Timer2 sfr16 TMR3 = 0xcc; // Timer3 //----------------------------------------------------------------------------- // Global Constants //----------------------------------------------------------------------------- #define uchar unsigned char #define uint unsigned int #define SYSCLK 49000000 // Output of PLL derived from (INTCLK*2) #define SAMPLE_RATE 50000 // Sample frequency in Hz #define INT_DEC 256 // Integrate and decimate ratio #define SAR_CLK 2500000 // Desired SAR clock speed #define SAMPLE_DELAY 50 // Delay in ms before taking sample #define Lcd_Data P2 sbit RS = P3^5; sbit RW = P3^6; sbit EN = P3^7; sbit LED = P4^6; // LED='1' means ON sbit SW1 = P4^0; // SW1='0' means switch pressed //----------------------------------------------------------------------------- // Function Prototypes //----------------------------------------------------------------------------- void OSCILLATOR_Init (void); void PORT_Init (void); void ADC0_Init (void); void TIMER3_Init (int counts); void ADC0_ISR (void); void Delay_Ms (unsigned int ms); void lcd_init(void); void write_command(uchar command); void write_data(uchar lcd_data); void lcd_clear(void); void write_str(uchar x , uchar y , uchar *s); void write_char(uchar x , uchar y, uchar lcd_data); void lcd_init(void); void lcd_display(); void delayus(uint n); void Buffer_Updata( int xx ); //----------------------------------------------------------------------------- // Global Variables //----------------------------------------------------------------------------- long Result; // ADC0 decimated value uchar Show_Buffer[ 16 ] = "Votage = 0.000 V"; //----------------------------------------------------------------------------- // main() Routine //----------------------------------------------------------------------------- void main (void) { long measurement; // Measured voltage in mV WDTCN = 0xde; // Disable watchdog timer WDTCN = 0xad; OSCILLATOR_Init (); // Initialize oscillator PORT_Init (); // Initialize crossbar and GPIO TIMER3_Init (SYSCLK/SAMPLE_RATE); // Initialize Timer3 to overflow at // sample rate ADC0_Init (); // Init ADC SFRPAGE = ADC0_PAGE; AD0EN = 1; // Enable ADC lcd_init(); lcd_clear(); EA = 1; // Enable global interrupts while (1) { EA = 0; // Disable interrupts measurement = Result * 2430 / 4095; EA = 1; // Re-enable interrupts LED = ~SW1; // LED reflects state of switch Buffer_Updata( measurement ); lcd_display(); Delay_Ms(SAMPLE_DELAY); // Wait 50 milliseconds before taking // another sample } } void Buffer_Updata( int xx ) { Show_Buffer[ 9 ] = xx / 1000 + '0'; Show_Buffer[ 11 ] = xx % 1000 /100 + '0'; Show_Buffer[ 12 ] = xx % 1000 %100 / 10 + '0'; Show_Buffer[ 13 ] = xx % 1000 %100 % 10 + '0'; } //----------------------------------------------------------------------------- // OSCILLATOR_Init //----------------------------------------------------------------------------- // // This function initializes the system clock to use the internal oscillator // at 24.5 MHz multiplied by two using the PLL. // //----------------------------------------------------------------------------- void OSCILLATOR_Init (void) { int loop; // Software timer char SFRPAGE_SAVE = SFRPAGE; // Save Current SFR page SFRPAGE = CONFIG_PAGE; // Set SFR page OSCICN = 0x83; // Set internal oscillator to run // at its maximum frequency CLKSEL = 0x00; // Select the internal osc. as // the SYSCLK source //Turn on the PLL and increase the system clock by a factor of M/N = 2 SFRPAGE = CONFIG_PAGE; PLL0CN = 0x00; // Set internal osc. as PLL source SFRPAGE = LEGACY_PAGE; FLSCL = 0x10; // Set FLASH read time for 50MHz clk // or less SFRPAGE = CONFIG_PAGE; PLL0CN |= 0x01; // Enable Power to PLL PLL0DIV = 0x01; // Set Pre-divide value to N (N = 1) PLL0FLT = 0x01; // Set the PLL filter register for // a refer