Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
8-2

Three of the internal peripherals have selectable clock sources.

•The asynchronous serial I/O (SIO) unit can use either the SERCLK signal or an external

clock (connected to the COMCLK pin) as its clock source.

•The synchronous serial I/O (SSIO) unit can use either the SERCLK signal or the PSCLK

signal.

•The timer/counters can use either the PSCLK signal or an external clock connected to the

TMRCLKn input pin.

The individual peripheral chapters explain how to select the clock inputs.

Figure 8-1. Clock and Power Management Unit Connections

A2470-02
INT
(From ICU)
NMI
SMI#
RESET
Power
Management
IDLE
PWRDN
To WDT
PWRDOWN
(pin mux)
CLKPRS
Programmable
Divider
÷2
Core
Buffer
Peripheral
Buffer
To Timer
To SIO0
To SIO1
To SSIO
To SSIO
To Peripherals
To Core
To Core
PSCLK
SERCLK
PH1C
PH2C
PH1P
To Peripherals
PH2P
÷2
Processor Clock
PH1/PH2
PWRCON
CLK2
CLKOUT
Async Reset