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AW: Interrupt Servicing

Started by Thomas Hupp July 8, 1999


-----Ursprungliche Nachricht-----
Von: Leigh Wells [SMTP:]
Gesendet am: Donnerstag, 8. Juli 1999 18:05
An:
Betreff: [c54x] Interrupt Servicing

Hi all:

I am using the '5410 eval board from Spectrum Digital and the TI
emulator. I have a question about Interrupt Service Routines. I am
using mnemonic assembly language only.

The way I understand it, when the CPU receives an interrupt from the
DMA, it jumps to the interrupt location (in my case 5ch), and reads the
branch instruction at this location to get to the ISR. What is the best

way to get the branch instruction into 5ch? Should I store the opcode
to 5ch and the address I want it to go to in 5dh?

[Thomas Hupp (TH)]

1. Give you interrupt routine a lable (example: _c_int00) an make the lable
global (.def _c_int00)
2. Make an assembler file to define the ir - vector table an give the table his
own section name (.vectors).
In this vector table refer to the lable of your isr as following:

.title "Vector Table"

.ref _c_int00

.sect ".vectors"

reset b _c_int00 ;0x00
nop
nop

nmi rete ;0x04
nop
nop
nop

.... and so on (be carfull that you use always 4 word for each interrupt) Also, once I get the ISR written, how should I get it to reside at the
program memory location that I want? For example, if I tell the CPU in
the branch instruction that I want it to branch to at 1000h, how should
I tell the compiler to put my ISR there? I have looked through the
documentation, and have been unable to decipher what the best way to do
this is.

[Thomas Hupp (TH)]
3. In the linker command file put the vector table to it right address:

MEMORY
{
PAGE 0:
......
VECS: origin = 0xff80, length = 0x0080 /* Interrupt Vectors */
......

}

SECTIONS
{
.vectors: > VECS PAGE 0
}
Any help would be greatly appreciated.

Leigh Wells
Electrical Engineer
Acoustic Positioning Research

[Thomas Hupp (TH)]
There are many way to do what you want - this is only one possibility

Regards
Thomas eGroups.com home: http://www.egroups.com/group/c54x
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