From: DavMac AT iname DOT com (Davin McCall)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: COM port interrupts don't happen?
Date: Wed, 18 Aug 1999 03:29:24 GMT
Organization: Monash Uni
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You have to enable the UART chip to send interrupts. 

IER (interrupt enable register) at 3F9h, 2F9h etc

bit 0 : 1 = enable recieved data available interrupt
bit 1 : 1 = enable transmitter holding register empty interrupt
bit 2 : 1 = enable reciver line status change interrupt
bit 3 : 1 = enable modem status change interrupt

Davin.


On Tue, 17 Aug 1999 19:15:42 -0400, "Martin Peach" <martin AT loplop DOT com>
wrote:

>I'm trying to process received characters from COM1. I have set up the UART
>and can receive OK by polling the device. I have set up a protected-mode
>interrupt routine which works fine if I assign INT0 (timer) interrupt to it.
>When I assign IRQ4 (INT0x0C, COM1) to it, nothing happens.
>The interrupt identification register says there is an interrupt pending
>when I poll it, the PIC mask has the corresponding bit cleared, the CPU ints
>are enabled using enable(), but my service routine is never called.
>Is this normal? I've tried this on a 486 and a pentium machine with
>identical results.
>What am I missing here?
>
>\/\/\/*= Martin
>
>

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