SC16C2552BIA44 NXP Semiconductors, SC16C2552BIA44 Datasheet - Page 16

• Manufacturer Part Number: SC16C2552BIA44
• Description: UART, 2 CH, 16BYTE FIFO, 16C2552
• Manufacturer: NXP Semiconductors

Specifications of SC16C2552BIA44

• No. Of Channels: 2
• Data Rate: 5Mbps
• Supply Voltage Range: 2.25V To 5.5V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: PLCC
• No. Of Pins: 44
• Svhc: No SVHC (18-Jun-2010)
• Operating: RoHS Compliant
• Uart Features: Independent Transmit & Receive UART Control, Multi-Function Output, Modem Control Functions
• Rohs Compliant: Yes

NXP Semiconductors
SC16C2552B_3
Product data sheet
7.4 Interrupt Status Register (ISR)
The SC16C2552B provides four levels of prioritized interrupts to minimize external
software interaction. The Interrupt Status Register (ISR) provides the user with four
interrupt status bits. Performing a read cycle on the ISR will provide the user with the
highest pending interrupt level to be serviced. No other interrupts are acknowledged until
the pending interrupt is serviced. Whenever the interrupt status register is read, the
interrupt status is cleared. However, it should be noted that only the current pending
interrupt is cleared by the read. A lower level interrupt may be seen after re-reading the
interrupt status bits.
interrupt levels and the interrupt sources associated with each of these interrupt levels.
Table 10.
Table 11.
Priority
level
1
2
2
3
4
Bit
7:6
5:4
3:1
0
Symbol
ISR[7:6]
ISR[5:4]
ISR[3:1]
ISR[0]
ISR[3]
0
0
1
0
0
Interrupt source
Interrupt Status Register bits description
5 V, 3.3 V and 2.5 V dual UART, 5 Mbit/s (max.), with 16-byte FIFOs
ISR[2]
1
1
1
0
0
Description
FIFOs enabled. These bits are set to a logic 0 when the FIFOs are not being
used in the 16C450 mode. They are set to a logic 1 when the FIFOs are
enabled in the SC16C2552B mode.
not used; initialized to a logic 0
INT priority bits. These bits indicate the source for a pending interrupt at
interrupt priority levels 1, 2 and 3 (see
INT status.
Table 10
Rev. 03 — 12 February 2009
logic 0 or cleared = default condition
logic 0 = an interrupt is pending and the ISR contents may be used as a
pointer to the appropriate interrupt service routine
logic 1 = no interrupt pending (normal default condition)
ISR[1]
1
0
0
1
0
shows the data values (bits 3:0) for the four prioritized
ISR[0]
0
0
0
0
0
Source of the interrupt
LSR (Receiver Line Status Register)
RXRDY (Received Data Ready)
RXRDY (Receive Data Time-out)
TXRDY (Transmitter Holding Register empty)
MSR (Modem Status Register)
Table
10).
SC16C2552B
© NXP B.V. 2009. All rights reserved.
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