68300

Jeff,

That sounds like a good idea.  I was using a 'transmit done' flag,
but this seems like a simpler approach.

By masking, I assume you mean the TIE (Transmit Interrupt Enable) in 
SCCR1, and not the interrupt level (0-7)

Thanks

John

--- In 68300@y..., jeffrey.tenney@g... wrote:
> 
> John,
> 
> Most of the time you don't want to acknowledge the interrupt if you 
have
> nothing to transmit.  You want to *mask* it.  Use the mask register.
> 
> Later when you put something into the transmit queue, restore the 
normal
> mask value.  The Tx interrupt will occur immediately, and you won't 
need
> special-case code in the send() routine.
> 
> Just a thought that might work for your situation.
> 
> Jeff
> 
> 
> 
> 
> 
> "john_gma" <johnshaffer@m...> on 09/10/2002 08:30:59 AM
> 
> Please respond to 68300@y...
> 
> To:    68300@y...
> cc:
> Subject:    [68300] MC68376 QSM SCI
> 
> 
> Hello all,
> 
> I am writing a serial driver for the QSM SCI.
> 
> My question is in regards to the interrupt handling.
> 
> There does not seem to be a separate ISR.
> How do I clear the interrupts?
> 
> There are 2 flags I need to use, TDRE and TC.
> 
> The book says that the flags are cleared by:
> 1. reading SCSR (OK, I do that)
> 2. Writing to TDR (I don't always want to do this)
> 
> So, how do I acknowledge the interrupt without transmitting 
something?
> 
> Can I write $0000 to SCSR?
> 
> Thanks
> 
> John
> 
> 
> 
> 
> 
> 
> 
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