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Hi, I use AT89S52 in a project. I send and receive data through TXD, RXD pins to a GSM module for sending SMS to another mobile equipment. I use watchdog facility and the watchdog counter is reset at every 256 counts. My crystal frequency is 11.0592 MHz. It happens once in a while that the uC doesn't respond and remains as if it hangs. Then it has to be RESET again. I doubt whether it happens while serial data reception and sending happens simultaneously. I wrote the program in C using KEIL IDE. My questions are 1) What are the special precautions to be taken in this case?(sending and receiving simultaneously) 2)why this happens even when the watchdog is active? It will be highly appreciated if anybody can give some guidance.
"makes that watchdog TOTALLY useless" Can you kindly elaborate this point or suggest some reading material to understand this point? A processor can go far astray and still have the timers running, thus feeding the WD in a timer ISR will make the watchdog NOT bite even if the code run astray.
Erik
Useful information. Thank you