saa5250 NXP Semiconductors, saa5250 Datasheet - Page 6

• Manufacturer Part Number: saa5250
• Description: Interface For Data Acquisition And Control For Multi-standard Teletext Systems
• Manufacturer: NXP Semiconductors

Philips Semiconductors
FUNCTIONAL DESCRIPTION
Microcontroller interface
The microcontroller interface communicates with the CPU via the handshake signals DB7 DB0, ALE, CS, RD, WR. The
microcontroller interface produces control commands as well as programming the registers to write their contents or read
incoming status/data information from the buffer memory. The details of the codes used to address the registers are
given in Table 2.
The CIDAC is ‘MOTEL’ compatible (MOTEL compatible means it is compatible with standard Motorola or Intel
microcontrollers). It automatically recognizes the microcontroller type (such as the 6801 or 8501) by using the ALE signal
to latch the state of the RD input. No external logic is required.
Table 1 Recognition signals
Table 2 CIDAC register addressing
January 1987
ALE
RD
WR
1
1
1
1
1
1
1
1
0
0
0
0
Interface for data acquisition and control
(for multi-standard teletext systems)
R
0
0
0
0
0
0
0
0
1
1
1
1
W
CIDAC
0
0
0
0
0
0
0
0
0
0
0
0
CS
CODES
0
0
0
0
1
1
1
1
0
0
0
0
DB2
0
0
1
1
0
0
1
1
0
0
1
1
DB1
ALE
RD
WR
0
1
0
1
0
1
0
1
0
1
0
1
DB0
8049/8051
TIMING 1
FUNCTION
write register R0
write register R1
write register R2
write register R3
write register R4
write register R5
write command register R6 (initialization command)
write register R7
read status
read data register
test (not used)
test (not used)
6
AS
DS, E,
R/W
2
6801/6805
TIMING 2
Product specification
SAA5250