Lpc2000

Hi,

It's now my second week in the presence of a Phillips ARM processor and 
I must say that it really rock's! However, due to my lack of experience 
with this wonder I face some problems getting the thing to obey all my 
orders :-)

I really appreciate the effort people are making in this mailing list to 
help each other and when I gain some experience I will do my best to 
repay my debt!

Playing with the SPI and SSP module left me with a couple of questions...

SPI speed:
I initialized the SPI module and to my surprise the clock was only 7.5 
MHz even though the core was running 60MHz. Then I saw in the datasheet 
that the SPI module only runs at 1/8 of the core speed. Can that really 
be true and why is that? 7.5MHz at max is close to useless in these days.

SSP interrupts:
In my design I have a DAC connected to the SSP module. The DAC needs 24 
bits for each conversion. Therefore I need to pull the SS low then send 
the 24bits and wait for the SSP modul to enter idle state (Checking the 
busy flag) then raise the SS again. Now I want to get this process to 
run automatically in interrupts. So I need to get an interrupt when the 
SSP is done... But it doesn't seem to be possible, the only flag 
available is the timeout flag and that is issued 32 clocks after the 
transmission ends. Which leaves me with a bit gab in the transmission. 
Is the timeout flag my only friend in this situation?

Interrupt problem:
I got timer vectored interrupts up and running just fine, however the 
SSP just won't request any interrupts. Here is a snippet of my code. 
Maybe it's very obvious what I'm doing wrong, but I can't see it.
As I said the other interrupts are working just fine, so I really can't 
see why the SSP interrupts won't work.
I'm using the CrossWorks compiler.

static void SSP_isr(void) __attribute__ ((interrupt ("IRQ")));
static void SSP_isr(void) {
  static uint8 ting;

  for(;;);

  VICVectAddr = 0;
}

void SSP_Init(void) {
  SSPCR0 = (0 << 8) | 0x47;  // Set phases and baud rate
  SSPCR1 = 0x02; // Enable SSP module
  SSPCPSR = 0x02; // Clock Prescale Register
  PINSEL1 |= 0x000002A8; // Map the SPI functionality to pins

  SSPIMSC = SSPIMSC_RORIM |SSPIMSC_RTIM | SSPIMSC_RXIM | SSPIMSC_TXIM; 
// Enable the interrupts
 
  VICIntSelect &= ~0x00000800;   // Map SSP to "IRQ"
  VICIntEnable = 0x00000800;      // Enable the SSP interrupt in the VIC
  VICVectCntl2 = 0x0000002B;     // Map SSP interrupt to VIC slot 2
  VICVectAddr2 = (unsigned int) SSP_isr; // Assign the interrupt handler
}

And one last question... is it possible to shift between the ARM and 
thumb mode realtime. Is it possible to make some of my functions in 
thumb mode and some in ARM mode? Any pragma to control the mode?

Thanks in advance! Hope that I have made some worthy questions!

Best regards
   Jan Thogersen