Lpc2000

I have tried to disable the UART1 interrupt both in the UART itself 
and in the VIC.  The problem is that as soon as the interrupts ar re-
enabled it is triggered.
When the 485 driver is set the read the bus the RX pin of the 2104 
is brought low this, I believe, is detected as a start condition and 
is the first false interrupt.  
When the driver is set to read the RX line is brought high.  I 
believe this is detected as a stop condition and presents a false 
00H as having been received.

Richard


--- In lpc2000@yahoogroups.com, onestone <onestone@b...> wrote:
> If the interrupt structure is anything like other micros you need 
to 
> disable any pending interrupt flags before re-enabling the 
interrupt, 
> since, whatever is causing the pulse (and I assume its caused by 
> switching the RS485 pins together) has caused a pulse anyway while 
ints 
> were disabled, and this has not yet been cleared.
> 
> Al
> 
> Richard wrote:
> 
> > 
> > I am driving a 485 transceiver (SN65HVD10) with the LPC2104.  The
> > RE/ and DE lines are tied together and to a GPIO pin for 
direction
> > selection.  My problem is that when I enable transmission the 
bus is
> > driven low and a pulse is seen at my RXD input causing an
> > interrupt.  I have tried disabling the UART1 interrupt before I
> > toggle the direction pins of the 485 transceiver but the receive
> > interrupt fires off as soon as I enable the UART interrupts 
again. 
> > Tying the direction pins of the tranceiver results in a race
> > condition so I have added a small delay to let the pins settle.
> > 
> > Thanks for the help
> > 
> > Richard
> > 
> > 
> > 
> > 
> > 
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