In-circuit emulation of a microprocessor mounted on a circuit board

摘要

In-circuit emulation of a processor that is mounted on a circuit board. The processor (20) is provided with isolation circuitry wherein a particular input signal regime causes all processor outputs to be disabled. The emulator cable (60) terminates in a set of contacts (62a- d, 75) configured to engage the processor pins (12a-d, 25). In the special case of a surface-mount processor, the contacts are mounted to fit over and around the processor and are spring-loaded. Provision is made via at least one of the probe contacts (75) to establish the specific input signal regime at the appropriate processor pin(s) (25) in order to isolate the processor pins from any processor output signals. This prevents any processor output signals from reaching the emulator or the rest of the board logic, thereby allowing the emulator to operate.