sc16c2552b NXP Semiconductors, sc16c2552b Datasheet - Page 22

• Manufacturer Part Number: sc16c2552b
• Description: Sc16c2552b 5 V, 3.3 V And 2.5 V Dual Uart, 5 Mbit/s Max. , With 16-byte Fifos
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 14442
Product data
7.10 Alternate Function Register (AFR)
7.9 Scratchpad Register (SPR)
The SC16C2552B provides a temporary data register to store 8 bits of user
information.
This is a read/write register used to select specific modes of MF operation and to
allow both UART register’s sets to be written concurrently.
Table 19:
Table 20:
Bit
7-3
2-1
0
AFR[2]
0
0
1
1
Symbol
AFR[7-3]
AFR[2-1]
AFR[0]
Alternate Function Register bits description
MFA, MFB function selection
5 V, 3.3 V and 2.5 V dual UART, 5 Mbit/s (max.), with 16-byte FIFOs
Rev. 02 — 13 December 2004
AFR[1]
0
1
0
1
Description
Not used. All are initialized to logic 0.
Selects a signal function for output on the MFA, MFB pins. These
signal functions are described as: OP2 (interrupt enable),
BAUDOUT, or RXRDY. Only one signal function can be selected
at a time. See
When this bit is set, CPU can write concurrently to the same
register in both UARTs. This function is intended to reduce the
dual UART initialization time. It can be used by CPU when both
channels are initialized to the same state. The external CPU can
set or clear this bit by accessing either register set. When this bit
is set, the Channel Select pin still selects the channel to be
accessed during read operation. Setting or clearing this bit has no
effect on read operations. The user should ensure that LCR[7] of
both channels are in the same state before executing a
concurrent write to the registers at address 0, 1, or 2.
Logic 0 = No concurrent write (normal default condition).
Logic 1 = Register set A and B are written concurrently with a
single external CPU I/O write operation.
MF function
OP2
BAUDOUT
RXRDY
reserved
Table
20.
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
SC16C2552B
22 of 37