Lpc2000

Curt
  Try connecting the READY line to an EINT pin configured as the ONLY FIQ interrupt,
then place the ACTUAL code for the FIQ service routine (not the LDR PC,... instruction)
in RAM at 0x001C.

-Bill Knight
R O SoftWare






On Mon, 12 Jan 2004 10:26:09 -0800, Curt Powell wrote:

We are interfacing to a peripheral usb chip and have come up with a
limitation that I'm having difficulty overcoming so I thought I'd post
this to the group to see if anyone has any suggestions.

Basically, when a READY pin goes high, the usb chip requires us to
initiate the followon write (by driving a WRITE pin low) within 360
nanoseconds.  Even writing in assembler, about the best I can
consistently do (detecting READY high and driving WRITE low) is 500+ns.
If anyone can suggest a trick to speed this up I'd appreciate their
input.  (BTW, we are running the CPU at 59+Mhz and vpb divider is 2)

Curt