ACS8520T Semtech, ACS8520T Datasheet - Page 43

• Manufacturer Part Number: ACS8520T
• Description: Synchronous Equipment Timing Source (SETS) for Stratum 3/4E/4 and SMC Systems
• Manufacturer: Semtech

Introduction to Microprocessor Modes
The ACS8520 incorporates a microprocessor interface, which can be configured for all common microprocessor
interface types, via the bus interface mode control pins UPSEL(2:0) as defined in Table 20.
These pins are read at power up and set the interface mode.
The optional EPROM mode allows the internal registers to be loaded from the EPROM when the device comes out of
“Power-On Reset” mode. The microprocessor interface type can be altered after power up by Reg. 7F, such that for
instance the device could boot up in EPROM mode and then switch to Motorola mode, for example, after the EPROM
data has preconditioned the device. Reading of Data from the EPROM at boot up time is handled automatically by the
ACS8520. The chip select of the EPROM should be driven from the micro in the case of mixed EPROM and micro
communication, in order to avoid conflict between EPROM and ACS8520 access from the microprocessor.
The following sections show the interface timings for each interface type.
Table 20 Microprocessor Interface Mode Selection
Timing diagrams for the different microprocessor modes are presented on pages 44 to 52.
Revision 3.02/October 2005 © Semtech Corp.
Microprocessor Interface
ADVANCED COMMUNICATIONS
UPSEL(2:0)
111 (7)
110 (6)
101 (5)
100 (4)
011 (3)
010 (2)
001 (1)
000 (0)
OFF
OFF
SERIAL
MOTOROLA
INTEL
MULTIPLEXED
EPROM
OFF
Mode
FINAL
Page 43
Interface disabled
Interface disabled
Serial uP bus interface
Motorola interface
Intel compatible bus interface
Multiplexed bus interface
EPROM read mode
Interface disabled
Description
ACS8520 SETS
DATASHEET
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