Lpc2000

Richard,

Regarding your earlier post, I was thinking in terms of delays added 
by breakpoints, or now reads.  In the code below, I see the dummy 
read in the SPI_setup() and not in SPI_IRQ().  I would have expected 
that a small delay between SPINT=1 and VICVectAddr=0 might have 
helped due to the timing differences between the 2 devices.

Aside from delays, I've seen this sort of thing when there is a 
posted write buffer involved.  If dummy is in SRAM, you've forced the 
eviction of whatever is there beforehand.  That's the only write 
buffer I know about on the LPC.  Is there posibly any buffering 
involved in the VPB bridge?


Tom


--- In lpc2000@yahoogroups.com, "Richard" <richas@y...> wrote:
> 
> Adding a read of the status register (SPSR) to the ISR solves the 
> problem.  Now to figure out why.......
> 
> 
> Richard
> 
> --- In lpc2000@yahoogroups.com, "Richard" <richas@y...> wrote:
> > 
> > I am putting togther simple SPI routines using an interrupt.  
What 
> I 
> > am see is that, if I put a breakpoint in the SPI ISR, I see the 
> byte 
> > get spit out and the program breaks where it ought to.  
> > Pressing "go" repeatadly sends out more bytes.  If I remove the 
> > breakpoint I expect to see repeated bytes sent out but, alas, I 
do 
> > not, I see one byte transmitted and the PC is in the delay loop 
> went 
> > I stop execution.
> > 
> > Keil uVision 3 (Using the KEIL ARM compiler)
> > Ulink
> > IAR Kickstart board
> > 
> > Thanks for the help
> > 
> > Richard
> > 
> > 
> > Code:
> > 
> > void VIC_setup (void)  {
> > 
> >   /* The SPI Interrupt is an IRQ   */
> >   VICIntSelect   &= ~0x400;
> >   /* Use slot 0 for SPI Interrupt  */
> >   VICVectCntl0 = 0x2A;
> >   /* Set address for of ISR in slot 0  */
> >   VICVectAddr0 = (unsigned long)SPI_IRQ;
> >   /* Enable SPI Interrupt  */			
> >   VICIntEnable   = 0x400;			
> > }
> > 
> > void SPI_IRQ (void) __irq {
> > 
> >   SPI_data = SPDR;		//read data register		
> > 			
> >   SPINT        = 1;                         // Clear interrupt 
flag
> >   VICVectAddr = 0;                         // Acknowledge 
Interrupt
> > 
> > }
> > 
> > void SPI_setup (void)	
> > 	{
> > 		SPCCR = 200; 	//  spi rate
> > 		SPCR = 0xA0;	// master mode, interrupt enabled
> > 		dummy = SPSR;
> > 	}
> > void IO_setup (void)//
> > 	{
> > 		IODIR = 0xff; // P0.0..7 defined as Outputs
> > 	    PINSEL0 = 0x5500; // enable spi i/o	
> > 	}
> > 
> >  unsigned char SPI_tfr(unsigned char SPI_data)
> >  	{
> > 		unsigned char val;
> > 
> > 		SPDR = SPI_data;
> > 	
> > 	}
> > 
> > 
> > int main (void) {
> > 
> > unsigned char pin;
> > unsigned long i;
> > 
> > 	SPI_setup();
> > 	IO_setup();
> > 	VIC_setup();
> >  
> > 	pin = 0;
> > 
> > 	while (1) {
> >  
> > //	if (pin) IOSET = 0x20; else IOCLR = 0x20;
> > 
> > //	pin ^= 1;
> > 	SPI_tfr(0xAA);
> > 	for(i=0; i<3000; i++);	  //kill some time to allow SPI 
> > interrupt
> > 	
> > 	
> > 
> > 	}
> > }