C161V_96 datasheet(21/260 Pages) SIEMENS

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10Jul97@15:19h

Architectural Overview / C161

The on-chip XBUS is an internal representation of the external bus and allows to access integrated

application-specific peripherals/modules in the same way as external components. It provides a

defined interface for these customized peripherals.

The C161 derivatives have no X-Peripherals implemented.

Clock Generator

The on-chip clock generator provides the C161 with its basic clock signal that controls all activities

of the controller hardware. Its oscillator can either run with an external crystal and appropriate

oscillator circuitry (see also recommendations in chapter „Dedicated Pins“) or it can be driven by an

external oscillator. The oscillator either directly feeds the external clock signal to the controller

hardware (through buffers, of course) or divides the external clock frequency by 2. This resulting

internal clock signal is also referred to as “CPU clock”. Two separated clock signals are generated

for the CPU itself and the peripheral part of the chip. While the CPU clock is stopped during the idle

mode, the peripheral clock keeps running. Both clocks are switched off, when the power down

mode is entered.

Figure 2-3

Clock Generation Block Diagram

C161 Clock Generation Modes

Prescaler operation. Default configuration after reset.

Direct drive: the maximum frequency depends on the duty cycle of the external clock signal.

In emulation mode pin P0.15 (P0H.7) is inverted, ie. the configuration ’1XX’ would select

direct drive in emulation mode.

Reset Configuration

P0.15-13 (P0H.7-5)

CPU Frequency

External Clock Input

Range

XTAL / 2

2 to 32 MHz

XTAL * 1

1 to 16 MHz 2)

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