5.1 Starting a debug session

To start interactive mode type ‘upad’ without specifying any file to upload. You should see a single prompt similar to ‘>’. At this prompt you can command µPad to perform operations for you.

There are two commands which are almost always needed immediately after starting a session. These are reset-bdm and sync. The first command puts the target into BDM mode. In this mode, program execution is stopped, and you can interrogate the CPU state as well as externally control it. The sync command is used to synchronise communication between the programmer and the target device. The programmer asks the target to send a pulse to indicate its bus speed. In this way, the programmer knows the correct speed to send and receive data. These two commands are used at the start of Figure 5.1.