User manual

MPLAB

REAL ICE

™

IN-CIRCUIT

EMULATOR USER’S GUIDE

Chapter 9. Frequently Asked Questions (FAQ)

9.1 INTRODUCTION

Look here for answers to frequently asked questions about the MPLAB REAL ICE

in-circuit emulator system.

• How Does It Work FAQs

• How Does Trace Work – 8 and 16 Bit Devices

•What’s Wrong

9.2 HOW DOES IT WORK FAQs

• What's in the silicon that allows it to communicate with the MPLAB REAL ICE

in-circuit emulator?

MPLAB REAL ICE in-circuit emulator can communicate with any silicon via the

ICSP interface. It uses the debug executive located in test memory.

• How is the throughput of the processor affected by having to run the debug

executive?

The debug executive doesn't run while in Run mode, so there is no throughput

reduction when running your code, i.e., the emulator doesn’t ‘steal’ any cycles

from the target device. However, when you are doing Native trace, each macro

inserted takes about 200 instructions. Therefore, this will affect timing.

For more information, see Section 7.3.9 “Resource Usage Examples”.

• How does the MPLAB REAL ICE in-circuit emulator compare with other in-circuit

emulators/debuggers?

Please refer to Section 2.2 “Tool Comparisons”.

• How does MPLAB IDE interface with the MPLAB REAL ICE in-circuit emulator to

allow more features than in-circuit debuggers?

For some devices, the MPLAB REAL ICE in-circuit emulator communicates using

the debug executive located in a special area of memory that does not use appli-

cation program memory. Also, the debug exec is streamlined for more efficient

communication. The emulator contains an FPGA, large SRAM Buffers (1Mx8),

and a high speed USB interface. The program memory image is downloaded and

is contained in the SRAM to allow faster programming. The FPGA in the emulator

serves as an accelerator for interfacing with the device in-circuit debugger

modules.

• On traditional emulators, the data must come out on the bus in order to perform a

complex trigger on that data. Is this also required on the MPLAB REAL ICE

in-circuit emulator? For example, could I halt based on a flag going high?

Traditional emulators use a special emulator chip (-ME) for monitoring. There is

no -ME with the MPLAB REAL ICE in-circuit emulator so there are no busses to

monitor externally. With the MPLAB REAL ICE in-circuit emulator, rather than

using external breakpoints, the built-in breakpoint circuitry of the debug engine is

used; the busses and breakpoint logic are monitored inside the part.