MPLAB ICD 3 In-Circuit Debugger User's Guide

MPLAB ® ICD 3 IN-CIRCUITDEBUGGER USER’S GUIDEChapter 6. Frequently Asked Questions (FAQs)6.1 INTRODUCTION6.2 HOW DOES IT WORKLook here for answers to frequently asked questions about the MPLAB ICD 3 in-circuitdebugger system.• How Does It Work• What’s Wrong• What's in the silicon that allows it to communicate with the MPLAB ICD 3in-circuit debugger?MPLAB ICD 3 in-circuit debugger can communicate with Flash silicon via theICSP interface. It uses the debug executive located in test memory.• How is the throughput of the processor affected by having to run the debugexecutive?• The debug executive doesn't run while in Run mode, so there is no throughputreduction when running your code, i.e., the debugger doesn’t ‘steal’ any cyclesfrom the target device. How does the MPLAB ICD 3 in-circuit debuggercompare with other in-circuit emulators/debuggers?Please refer to Section 2.2 “MPLAB ICD 3 In-Circuit Debugger vs. MPLAB ICE2000/4000 In-Circuit Emulators” and Section 2.3 “MPLAB ICD 3 In-CircuitDebugger vs. MPLAB ICD 2 Debugger”.• How does MPLAB IDE interface with the MPLAB ICD 3 in-circuit debugger toallow more features than MPLAB ICD 2?MPLAB ICD 3 in-circuit debugger communicates using the debug executivelocated in the test area. The debug exec is streamlined for more efficient communication.The debugger contains an FPGA, large SRAM Buffers (1Mx8) and aHigh Speed USB interface. Program memory image is downloaded and is containedin the SRAM to allow faster programming. The FPGA in the debuggerserves as an accelerator for interfacing with the device in-circuit debuggermodules.• On the MPLAB ICE 2000/4000 debuggers, the data must come out on thebus in order to perform a complex trigger on that data. Is this also requiredon the MPLAB ICD 3 in-circuit debugger? For example, could I halt based ona flag going high?The MPLAB ICE 2000/4000 debuggers use a special debugger chip (-ME) formonitoring. There is no -ME with the MPLAB ICD 3 in-circuit debugger so thereare no busses to monitor externally. With the MPLAB ICD 3 in-circuit debugger,rather than using external breakpoints, the built-in breakpoint circuitry of thedebug engine is used – the busses and breakpoint logic are monitored inside thepart.© 2008 Microchip Technology Inc. DS51766A-page 49