Eurotech Appliances PXA255 Bit, Name, Value Function, PC/104 interrupts under embedded Linux and VxWorks

VIPER Technical Manual Detailed hardware description

ICR Bit Functions

Bit Name Value Function

0 No interrupt retrigger (embedded Linux and VxWorks)

0 RETRIG

1 Interrupt retrigger (Windows CE)

0

1 AUTO_CLR

1

No auto clear interrupt / Toggle GPIO1 on new interrupt (embedded Linux and VxWorks)

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

1Board reset disable (Set before entering CPU sleep)

0CompactFlash 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’:

GPIO1

Level

1st IRQ	1st IRQ	1st IRQ	1st IRQ	2nd IRQ
on IRQ7	on IRQ15	on IRQ12	on IRQ7	on IRQ7
			serviced

Time

Once the VIPER microprocessor has serviced a PC/104 interrupt, clear the corresponding bit in the corresponding PC104I register by writing ‘1’ to it.

© 2007 Eurotech Ltd Issue E 32