First time designing a PCB board whith a MPC82G516AP (8051),I'm using an external Watchdog Timer chip。So is the watchdog reset valid while programming with ISP?
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2A schematic of the relevant part of the circuit (watchdog + 8051 + ISP) would help formulate a useful response. – Anindo Ghosh Apr 02 '13 at 09:13
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During programming your code will not run, hence it will not produce the watchog-silencing signal. So your watchdog will trip when programming takes longer than its timeout.
I don't know the details of MCP82 programming, but on all other chips I know a reset in the middle of the programming will cause errors. Hence you must prevent the watchdog chip from resetting the target chip during programming.
This can be done with various means, ranging from not fitting the watchdog chip (DIP?) during programming, to a jumper (solder or 'real') that is to be fitted after programming. If the programmer actively drives the rest line, a suitable resistor between the reset chip and the target chip might be a nice solution.
Wouter van Ooijen
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