UART Serial Ports
Élan™SC520 Microcontroller User’s Manual 21-13
21.5.7.3 Interrupt Disable
Each UART interrupt request can be disabled (gated low) prior to the programmable
interrupt controller by clearing to 0 the OUT2 bit in the UART x Modem Control (UARTxMCR)
register. Note that setting the LOOP bit in the MCR also disables the UART interrupt request.
Therefore, interrupts are not propagated to the PIC while in loopback mode.
21.6 INITIALIZATION
At system reset, the serial port is disabled. To be enabled, it must be configured by software.
1. Configure the UART by programming the desired baud rate, character length, stop-bits,
and parity.
2. Enable interrupts and DMA operation as desired. Note that for UART interrupts to
propagate to the programmable interrupt controller, the OUT2 bit in the UART x Modem
Control (UARTxMCR) register must be set to 1.
After the UART is enabled, it powers up as a 16450-compatible device. It can be switched
between 16550-compatible mode and 16450-compatible mode under software control.
3. Enable 16550-compatible mode by setting the FIFO_ENB bit of UART x FIFO Control
(UARTxFCR) register. Note that the contents of this write-only register can be read back
in the UART x FIFO Control Shadow (UARTxFCRSHAD) register.
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