ARM7入門3，A/D轉換

主程序：

/******************************************************************************/
/* This file is part of the uVision/ARM development tools */
/* Copyright KEIL ELEKTRONIK GmbH 2002-2004 */
/******************************************************************************/
/* */
/* BLINKY.C: LED Flasher */
/* */
/******************************************************************************/

#include /* LPC21xx definitions */

extern void init_serial (void); /* Initialize Serial Interface */
extern int putchar (int ch); /* Write character to Serial Port */
extern int getchar (void); /* Read character from Serial Port */

void puthex (int hex) { /* Write Hex Digit to Serial Port */
if (hex > 9) putchar('A' + (hex - 10));
else putchar('0' + hex);
}

void putstr (char *p) { /* Write string */
while (*p) {
putchar (*p++);
}
}

void delay (void) { /* Delay function */
unsigned int cnt;
unsigned int val;

ADCR |= 0x01000000; /* Start A/D Conversion */
do {
val = ADDR; /* Read A/D Data Register */
} while ((val & 0x80000000) == 0); /* Wait for end of A/D Conversion */
ADCR &= ~0x01000000; /* Stop A/D Conversion */
val = (val >> 6) & 0x03FF; /* Extract AIN0 Value */

putstr ("nAIN0 Result = 0x"); /* Output A/D Conversion Result */
puthex((val >> 8) & 0x0F); /* Write 1. Hex Digit */
puthex((val >> 4) & 0x0F); /* Write 2. Hex Digit */
puthex (val & 0x0F); /* Write 3. Hex Digit */

val = (val >> 2) << 12; /* Adjust Delay Value */
for (cnt = 0; cnt < val; cnt++); /* Delay */
}

int main (void) {
unsigned int n;

IODIR1 = 0x00FF0000; /* P1.16..23 defined as Outputs */
ADCR = 0x002E0401; /* Setup A/D: 10-bit AIN0 @ 3MHz */
init_serial(); /* Initialize Serial Interface */
IOSET1=0x00ff0000;
while (1) { /* Loop forever */
for (n = 0x00010000; n <= 0x00800000; n <<= 1) {
/* Blink LED 0, 1, 2, 3, 4, 5, 6, 7 */
IOCLR1 = n; /* Turn on LED */
delay(); /* Delay */
IOSET1 = 0x00FF0000; /* Turn off LEDs */
}
}
}
串口程序：

/******************************************************************************/
/* This file is part of the uVision/ARM development tools */
/* Copyright KEIL ELEKTRONIK GmbH 2002-2004 */
/******************************************************************************/
/* */
/* SERIAL.C: Low Level Serial Routines */
/* */
/******************************************************************************/

#include /* LPC21xx definitions */

#define CR 0x0D

void init_serial (void) { /* Initialize Serial Interface */
PINSEL0 = 0x00050000; /* Enable RxD1 and TxD1 */
U1LCR = 0x83; /* 8 bits, no Parity, 1 Stop bit */
U1DLL = 97; /* 9600 Baud Rate @ 15MHz VPB Clock */
U1LCR = 0x03; /* DLAB = 0 */
}

int putchar (int ch) { /* Write character to Serial Port */

if (ch == 'n') {
while (!(U1LSR & 0x20));
U1THR = CR; /* output CR */
}
while (!(U1LSR & 0x20));
return (U1THR = ch);
}

int getchar (void) { /* Read character from Serial Port */

while (!(U1LSR & 0x01));

return (U1RBR);
}