ICE2000 datasheet(4/18 Pages) MICROCHIP

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MPLAB® ICE 2000

DS51140M-page 4

4.3.2

CLOCK SOURCE FROM THE TARGET

APPLICATION

If the target application is selected to provide the clock

source, the target board must also be selected to

power the emulator processor (see the MPLAB ICE

2000 on-line help file in MPLAB IDE (Help>Topics) or

the “MPLAB® ICE 2000 In-Circuit Emulator User’s

Guide” (DS51488), “Using a Target Board Clock”).

At low voltage, the maximum speed of the processor

will be limited to the rated speed of the device under

emulation.

An oscillator circuit on the device adapter generates a

clock to the processor module and buffers the clock

circuit on the target board. In this way, the MPLAB ICE

2000 emulator closely matches the oscillator options of

the actual device. All oscillator modes are supported

(as documented in the device’s data sheet) except as

noted in Section 3.0 “Emulator-Related Issues”. The

OSC1 and OSC2 inputs of the device adapter have a

5 pF to 10 pF load. Be aware of this when using a

crystal in HS, XT, LP or LF modes, or an RC network in

RC mode.

The frequency of the emulated RC network may vary

relative to the actual device due to emulator circuitry.

If a specific frequency is important, adjust the RC val-

ues to achieve the desired frequency. Another alterna-

tive would be to allow the emulator to provide the

clock as described in Section 4.3.1 “Clock Source

from Emulator”.

When using the target board clock, the system’s

operating voltage is between 2.5V and 5.5V.

4.4

ESD Protection and Electrical

Overstress

All CMOS chips are susceptible to electrostatic

discharge (ESD). In the case of the processor modules,

the pins of the CMOS emulator are directly connected

to the target connector, making the chip vulnerable to

ESD. ESD can also induce latch-up in CMOS chips,

causing excessive current through the chip and

possible damage. MPLAB ICE 2000 has been

designed to minimize potential damage by implement-

ing overcurrent protection and transient suppressors.

However, care should be given to minimizing ESD

conditions while using the system.

During development, contention on an I/O pin is

possible (e.g., when an emulator pin is driving a ‘1’ and

the target board is driving a ‘0’). Prolonged contention

may cause latch-up and damage to the emulator chip.

One possible precaution is to use current limiting

resistors (~100

Ω) during the development phase on

bidirectional I/O pins. Using limiting resistors can also

help avoid damage to modules, device adapters and

pods that occurs when a voltage source is accidentally

connected to an I/O pin on the target board.

4.5

Freeze Mode

The MPLAB ICE 2000 system allows the option of

“freezing” peripheral operation or allowing them to

continue operating when the processor is halted. This

option is configured in the MPLAB IDE. The Freeze

function is available on all processor modules except

the PCM16XA0.

This function is useful to halt an on-board timer while at

a break point. At a break point and while single

stepping, interrupts are disabled.

5.0

DEVICE ADAPTER ISSUES

This section details processor-specific considerations

that have been made on device adapters. Only

adapters with special considerations are listed.

There will be a max of 10 mA of current draw from the

target system even when the emulator processor

module is being powered by the emulator system, and

running internal clock. This is due to components on

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