Test Equipment, Debuggers, Development Systems

Test Equipment

Name Cost Pros Cons

Logic Probe $2-$20 Handy, cheap Only sees one line,
Does not record in real time (may have a pulse LED to show AC signals)

Logic Analyzer $200-$2000
(speed) Can record events in real time.
Some can disassemble machine code to provide more readable diagnostics. May not see the signal the same way the circuit under test sees it due to differing level sensitivities or differences in timing of the sampling.

Oscilloscope
(Analog, with trigger) $300-$5000
(depending on speed) Can view composites of events (detected by external trigger circuit) in real time.
Displays the entire signal including the exact voltage and timing (if the scope is faster and more accurate than the signal). Really shows what the circuit is seeing (probably). Non-recording models do not show individual signals but instead display a composite of many copies of the same signal one on top of the next. Isolated incidents may be missed.
Can display only one or two signals (called channels or traces) at a time.
If the signal changes fast enough, the 'scope may miss it.
Doesn't know how the circuit will respond to the signal.

Oscilloscope
(Digital) $1000-$50,000
(depending on speed) Can record and view individual events (detected by external trigger circuit) in real time.
Displays the entire signal including the exact voltage and timing. Really shows what the circuit is seeing. Can display only one or two signals (called channels or traces) at a time.
If the signal changes fast enough, the 'scope may miss it.
Doesn't know how the circuit will respond to the signal.

Mixed Mode DSO $1000-$100,000
(depending on speed) Combination of a Digital Oscilloscope with a Logic Analyzer. All the advantages... If the signal changes fast enough, the 'scope may miss it.
Doesn't know how the circuit will respond to the signal.

In Circuit Emulators (I.C.E.) $2000-$100,000
(except for Ubicom, Microchip and AVR? at about $200) Should allow recording from the point of view of the circuit (so the signal levels and timing don't matter). What you see is what it got (not necessarily what it saw).
Allows single step and easy setup of multiple breakpoints to stop execution when a set condition occurs. Often supports stack traces and history capture. Just tells you how the processor saw the signal, not why the signal was seen that way (Was there a spike? Was the signal weak? Is the timing wrong? etc..)
The emulator may respond differently than the production component (screwed up in actual operation, works fine when you plug in the emulator.. hah-hah) (except for Ubicom and the Microchip 16F87x as they build the emulation circuitry into the production chip.)
Many emulators will not correctly support external events like IO port signals and interrupts.

Simulators Free to $1000 Allows testing of basic code and ideas without even needing to have the device.
Can show everything including. long list. Not real time, not real (simulations are doomed to succeed). Will not catch all the Gotchas.

Also:

Software Tips, Tricks, Traps, Gens and Snares

Debuggers

Ralph Stickleys' Serial Register Monitor

Name	Cost	Pros	Cons
Logic Probe	$2-$20	Handy, cheap	Only sees one line, Does not record in real time (may have a pulse LED to show AC signals)
Logic Analyzer	$200-$2000 (speed)	Can record events in real time. Some can disassemble machine code to provide more readable diagnostics.	May not see the signal the same way the circuit under test sees it due to differing level sensitivities or differences in timing of the sampling.
Oscilloscope (Analog, with trigger)	$300-$5000 (depending on speed)	Can view composites of events (detected by external trigger circuit) in real time. Displays the entire signal including the exact voltage and timing (if the scope is faster and more accurate than the signal). Really shows what the circuit is seeing (probably).	Non-recording models do not show individual signals but instead display a composite of many copies of the same signal one on top of the next. Isolated incidents may be missed. Can display only one or two signals (called channels or traces) at a time. If the signal changes fast enough, the 'scope may miss it. Doesn't know how the circuit will respond to the signal.
Oscilloscope (Digital)	$1000-$50,000 (depending on speed)	Can record and view individual events (detected by external trigger circuit) in real time. Displays the entire signal including the exact voltage and timing. Really shows what the circuit is seeing.	Can display only one or two signals (called channels or traces) at a time. If the signal changes fast enough, the 'scope may miss it. Doesn't know how the circuit will respond to the signal.
Mixed Mode DSO	$1000-$100,000 (depending on speed)	Combination of a Digital Oscilloscope with a Logic Analyzer. All the advantages...	If the signal changes fast enough, the 'scope may miss it. Doesn't know how the circuit will respond to the signal.
In Circuit Emulators (I.C.E.)	$2000-$100,000 (except for Ubicom, Microchip and AVR? at about $200)	Should allow recording from the point of view of the circuit (so the signal levels and timing don't matter). What you see is what it got (not necessarily what it saw). Allows single step and easy setup of multiple breakpoints to stop execution when a set condition occurs. Often supports stack traces and history capture.	Just tells you how the processor saw the signal, not why the signal was seen that way (Was there a spike? Was the signal weak? Is the timing wrong? etc..) The emulator may respond differently than the production component (screwed up in actual operation, works fine when you plug in the emulator.. hah-hah) (except for Ubicom and the Microchip 16F87x as they build the emulation circuitry into the production chip.) Many emulators will not correctly support external events like IO port signals and interrupts.
Simulators	Free to $1000	Allows testing of basic code and ideas without even needing to have the device. Can show everything including.	long list. Not real time, not real (simulations are doomed to succeed). Will not catch all the Gotchas.