Re: [linuxsh-dev] !!! HELP !!!! In asm/irq or irq_ipr is there a function to set IRQn Sense Select

[Stuart M. <stu...@st...>]

Hi there

On Tue, 9 Apr 2002 15:14:32 +0200
fg...@ti... wrote:

> Hi,
> 
> where could I set the Sense Select of My IRQs?

From what I can see in a brief scan of the 7709a manual, the IRQ0-3 pins
can be used either in encoded (IRL mode), or as individual pins
(IRQ mode). It looks like IRQ4-5 are always in IRQ mode.

In encoded mode, you have no choise over the trigger mode. In IRQ mode
you can choose rising edge, falling edge or active low.
No option for active high. 

Look at Interrupt Control Register 1 (ICR1) for how to set all this up.

The PINT interrupts look to be programmable for active high or low
though, using Interrupt Control Register 2 (ICR2).

Unfortuntaly the interrupt systems on the various SuperH chips are not
orthogonal. Each device has its own set of additions to the basic
feature set, so its quite likely that a particular feature may only
be present on a subset of the interrupts on a particular device. So for
example, just because the PINT interrupts can be programmed for active
high/low, don't expect the IRQ interrupts to be similarly programmable.

> Again, where and how I can an IRQ form a companion chip multiplaxing the 
> interrupt sources?

We've always done it using an FPGA or GAL. But I would guess a standard
priority encoder, something like a 74HCT147, would do the job.

Stuart

-- 
Stuart Menefy                                        stu...@st...
STMicroelectronics Ltd                         ST Intranet: mo.bri.st.com
Bristol, UK                         Rest of the World: www.linuxsh.st.com