[Tinyos-host-mote-wg] Re: [Tinyos-2.0wg] Interrupt interface

[Philip Levis]

On Oct 20, 2005, at 12:04 PM, Phil Buonadonna wrote:

>
> The 'enable' function of the interrupt interface
> (tos/interfaces/Interrup.nc) takes as an argument a flag to  
> determine wether
> it should fire on a rising or falling edge.  This implies that the  
> interrupt
> is based on a digital signal transition (i.e. a GPIO pin) rather  
> than a
> generic peripheral interrupt in which there is no notion of 'edge
> transition' but rather just an event.

What do you mean by "generic peripheral interrupt?" So far, the  
Interrupt interface has not been used for internal devices (e.g.,  
SPI, UART); instead, their interrupts are controlled through a device  
specific interface.
>
> The docs of the interface say that it is microcontroller  
> independent, but it
> really isn't in this case. It is specific to 1) Digital (GPIO)  
> signals and
> 2) interrupt controllers that can fire on only one type of transition:
> rising OR falling BUT NOT both. (As I understand it, this is  
> because the
> ATmega128 is limited to this case)
>

I actually think it came out of the MSP430 code. But you're right,  
the possibility of both can't be covered. Hm. What sorts of chips  
support that? The PX?

> Proposals:
> 1) Move interrupt to a new interface called GPIOInterrupt and  
> create a new
> Interrupt.nc in which there is only an enable feature.

This ignores the "I can do one or both" possibility...

> -or- 2) Keep the present interface, but document 'enable()' where the
> argument is optional (seems kludgy)
>

Agreed.

> As for the double edge trigger issue, one option is to simply not  
> accomodate
> this function in TOS 2.0.  That is, in TOS 2.0 you can define a  
> GPIO trigger
> on a rising edge XOR falling edge. Which is fine, if that's the  
> consensus

I am wary of doing this unless we understand the design space better.

Phil
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