Motorola USB08 Betriebsanleitung PDF herunterladen (Seite 78)

11 ERRORS

11.1 Communication and Echo Errors

When Xplor8 sends a byte to the monitor firmware it usually expects to receive an echoed byte. By

comparing the transmitted and received bytes, the program is able to assure the integrity of the RS232

communications link. If the echo is wrong, Xplor8 shows an error dialog. Two classes of byte error

may be distinguished: Errors in the command byte received by the monitor firmware and errors in bytes

being written to memory. These are referred to, for convenience, as ‘Comms Errors’ and ‘Echo

Errors’.

11.1.1 Comms Error

This occurs when Xplor8 loses synchronisation with the monitor firmware on board the MCU. The

command byte sent to the MCU to initiate a command has been wrongly echoed back to Xplor8. This

usually happens when:

• The stack has been accidentally overwritten, or

• an operation has left the MCU in an unknown state.

It is usually necessary to reset the MCU and re-enter monitor mode when this happens. Where remote

reset is available, the dialog appears with [Yes] and [No] buttons, allowing you to click [Yes] for an

immediate re-boot.

When this error occurs, Xplor8 writes diagnostic information to the Output Window - See Diagnostics

on page 79.

11.1.2 Echo Error

This occurs when Xplor8 is sending data and the MCU target echoes back a different character from

the one that was sent. This happens when:

• the memory at an address could not be altered. It might, for example, be a location in ROM,

or a location in FLASH when the bits in the FLBPR register do not allow writing to FLASH,

• the memory at an address is a control register which has one or more read-only bytes, or

It should not be necessary to reset the MCU after this error as communication has not been lost.

Note that this error can occur part way through the execution of a command, so that some memory

may have been correctly written, while some may not be written at all.

When this error occurs, Xplor8 writes diagnostic information to the Output Window - See Diagnostics

below.

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Motorola USB08 Betriebsanleitung Seite 78