Lpc2000

In an interrupt service routine:
in order to exit it properly you must, Clear the interrupt flag that 
triggered it (write a 1 to the flag?) eg:
U0IIR 	= 0x0000000A;	//Clear the interrupt register

anyway, most importantly you also need to write to teh vector 
address register:
eg:
VICVectAddr 	= 0x00000000;//Dummy write to signal end of interrupt

failure to do these will lead to continuous interrupts.....


Does this help???

rgds
pete


--- In lpc2000@yahoogroups.com, "peterburdine" <lordofdawn@h...> 
wrote:
> 
> I think I may be missing something stupid, but can anyone help me?
> I am tring to write to UART0, but it doesn't seem to work.  I am
> trying to write a software buffer to help out the one byte hardware
> buffer.  Specifically I am using the LPC 2294.  Below is my code.
> 
> I am using the Keil toolset (compiler/debugger/simulator).  The 
code
> works perfectly fine when running it on the simulator, but when I 
try
> to run it on the chip, I will only get "ho" instead of "hello".  I 
put
> some break points in it when using JTAG to debug, but the ISR is 
never
> called when running on the real hardware, it is called on the
> simulator.  Also, when I debug on JTAG I never se the THRE or TEMT
> clear.  Can you see anything obviously wrong?  I think I put in
> everything that you need to compile it.
> 
> #include <stdio.h>
> #define TX_BUFFER_LENGTH 64
> #define UART0_THRE			(U0LSR & 0x20)
> #define		PINSEL0_00_TxD		(0x01)
> #define		PINSEL0_01_GPIO		(0x00 << 2)
> #define U0RBR          (*((volatile unsigned char *) 0xE000C000))
> #define U0THR          (*((volatile unsigned char *) 0xE000C000))
> #define U0IER          (*((volatile unsigned char *) 0xE000C004))
> #define U0IIR          (*((volatile unsigned char *) 0xE000C008))
> #define U0FCR          (*((volatile unsigned char *) 0xE000C008))
> #define U0LCR          (*((volatile unsigned char *) 0xE000C00C))
> #define U0MCR          (*((volatile unsigned char *) 0xE000C010))
> #define U0LSR          (*((volatile unsigned char *) 0xE000C014))
> #define U0MSR          (*((volatile unsigned char *) 0xE000C018))
> #define U0SCR          (*((volatile unsigned char *) 0xE000C01C))
> #define U0DLL          (*((volatile unsigned char *) 0xE000C000))
> #define U0DLM          (*((volatile unsigned char *) 0xE000C004))
> #define VICVectAddr6   (*((volatile unsigned long *) 0xFFFFF118))
> #define VICVectCntl6   (*((volatile unsigned long *) 0xFFFFF218))
> #define VICIntSelect   (*((volatile unsigned long *) 0xFFFFF00C))
> #define VICIntEnable   (*((volatile unsigned long *) 0xFFFFF010))
> #define VICIntEnClr    (*((volatile unsigned long *) 0xFFFFF014))
> static Uint16	txBytes = 0;
> static Uint16	txRdPos = 0;
> static Uint16	txWrPos = 0;
> static Uint16	txBuffer[TX_BUFFER_LENGTH];
> 
> void uart0_config (void);
> void uart0_isr (void);
> void uart0_sendByte (Uint8);
> int putchar(int);
> int main (void);
> 
> void uart0_config (void) {
> 	// Setup UART 0
> 	U0LCR = 0x80; // Enable DLAB
> 	U0DLL = 0x16; // Setup BGR
> 	U0DLM = 0x05; // ~2400 Bit/s @ 50 Mhz
> 	U0LCR = 0x03; // Enable UART 0, 8 bits, no parity, 1 stop bit
> 
> 	// Reset the FIFOs
> 	U0FCR = 0xC7; // RX FIFO trigger level 8 chars, reset tx and 
rx fifo,
> enable fifos
> 
> 	// Setup Interrupts for UART0
> 	U0IER = 0x7;
> 	VICIntSelect &= 0x0;
> 	VICVectCntl6 = 0x20 | 6;
> 	VICVectAddr6 = (unsigned long) uart0_isr;
> 	VICIntEnable |= (0x1 << 6); // Enable Uart0 Interrupt	
> }
> 
> void uart0_isr (void) __irq {
> 	switch((U0IIR>>1)&0x7) {
> 		// THRE
> 		case	001:
> 			if(txBytes != 0) {
> 				U0THR = txBuffer[txRdPos];
> 				txRdPos++;
> 				txRdPos = (txRdPos == 
TX_BUFFER_LENGTH)?0:txRdPos;
> 				txBytes--;
> 			}
> 			break;
> 	}
> }
> 
> void uart0_sendByte(Uint8 byte) {
> 	// Wait until there is room in the buffer
> 	while(txBytes == TX_BUFFER_LENGTH);
> 	VICIntEnClr |= (1 << 6);
> 	if(!UART0_THRE) {  // Put it in the software buffer 
> 		txBuffer[txWrPos] = byte;
> 		txWrPos++;
> 		txWrPos = (txWrPos == TX_BUFFER_LENGTH)?0:txWrPos;
> 		txBytes++;
> 	}
> 	else { // If the chip buffer is empty, put it there
> 		U0THR = byte;	
> 	}
> 	VICIntEnable |= (1 << 6);
> }
> 
> int putchar(int a) {
> 	uart0_sendByte((int)a);
> }
> 
> int main (void) {
> 	PINSEL0 = PINSEL0_00_TxD | PINSEL0_01_RxD; 
> 	printf("hello");
> }