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IDT UART Controller
UART Interrupts
79RC32438 User Reference Manual
13 - 4
November 4, 2002
Notes
UART Interrupts
The UART generates six interrupt requests to the interrupt controller:
General
Interrupt 0
. Activated when one of the conditions in the UART0IE register is enabled and
the necessary condition has occurred. This is bit (0) in the UART0II register, inverted, and sent to
the interrupt controller.
TXRDY 0 Interrupt.
Activated depending on the DMA mode set in the FIFO Control Register for
channel 0. An interrupt request is generated under the same conditions that the TXRDY pin for
channel 0 would be asserted. (Refer to industry standard 16550 UART specification.)
1
RXRDY 0 Interrupt
. Activated depending on the DMA mode set in the FIFO Control Register for
channel 0. An interrupt request is generated under the same conditions that the RXRDY pin for
channel 0 would be asserted. (Refer to industry standard 16550 UART specification.)
1
General
Interrupt 1
. Activated when one of the conditions in the UART1IE register is enabled and
the necessary condition has occurred. This is bit (0) in the UART1II register, inverted, and sent to
the interrupt controller.
TXRDY 1 Interrupt.
Activated depending on the DMA mode set in the FIFO Control Register for
channel 1. An interrupt request is generated under the same conditions that the TXRDY pin for
channel 1 would be asserted. (Refer to industry standard 16550 UART specification.)
1
RXRDY 1 Interrupt
. Activated depending on the DMA mode set in the FIFO Control Register for
channel 1. An interrupt request is generated under the same conditions that the RXRDY pin for
channel 1 would be asserted. (Refer to industry standard 16550 UART specification.)
1
UART Channel Reset
The UART provides two independent serial channels. When switching a UART channel between 16550
and 16450 modes, the internal UART FIFOs are not cleared. To support clean switching between modes, a
UART Reset Register (UART[0|1]RR) is added to the standard 16550 UART register definition for each
channel.
The standard 16550 UART registers are described in the Functional Overview section at the beginning
of this chapter.
UART Registers
This section describes the UART registers. For additional information on configuring and operating the
UART, see the 16550 data sheet
2
.
66MHz
9600
430
66MHz
2400
1719
50MHz
9600
326
40MHz
9600
260
33MHz
9600
215
25MHz
9600
163
1.
PC 16550D Dual Universal Asynchronous Receiver/Transmitter with FIFOs
, June 1995, National Semicon-
ductor
.
2.
PC 16550D Dual Universal Asynchronous Receiver/Transmitter with FIFOs
, June 1995, National Semicon-
ductor.
IPBus Clock
Frequency
Baud Rate
Divisor (decimal)
Table 13.3 Divisor Values for Typical Baud Rates and IPBus Clock Frequencies (Part 2 of 2)