Eurotech Appliances VIPER / VIPER-LITE PXA255 - Manual (Page 32)

VIPER Technical Manual Detailed hardware description
© 2007 Eurotech Ltd Issue E 32
ICR Bit Functions
Bit Name Value Function
0 No interrupt retrigger (embedded Linux and VxWorks)
0 RETRIG
1 Interrupt retrigger (Windows CE)
0
No auto clear interrupt / Toggle GPIO1 on new interrupt
(embedded Linux and VxWorks)
1 AUTO_CLR
1
Auto clear interrupt / pulse low for 1.12µs on GPIO1 on
new interrupt from a new interrupt source (Windows CE)
0 Board reset normal
2 R_DIS
1 Board reset disable (Set before entering CPU sleep)
0 CompactFlash reset controlled by board reset
3 CF_RST
1 Reset CompactFlash
4 - 7 - X No function
PC/104 interrupts under embedded Linux and VxWorks
Leave the ICR register set to its default value, so that a new interrupt causes the
microprocessor PC/104 interrupt pin GPIO1 to be toggled for every new interrupt on a
different PC/104 interrupt source. Ensure the GPIO1 input is set up in a level triggered
mode. The retrigger interrupt function is not required for embedded Linux or VxWorks.
The following diagram gives an example of how the PC/104 interrupt on GPIO1
behaves over time when the ICR AUTO_CLR bit is set to ‘0’:
Once the VIPER microprocessor has serviced a PC/104 interrupt, clear the
corresponding bit in the corresponding PC104I register by writing ‘1’ to it.
1 st IRQ
on IRQ7
1 st IRQ
on IRQ15
1 st IRQ
on IRQ12
2 nd IRQ
on IRQ7
GPIO1
Level
Time
1 st IRQ
on IRQ7
serviced