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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.
you can get a 'tripod' (a supervisor chip in a 'transistor package') such as DS1233 datasheets.maxim-ic.com/.../DS1233.pdf which can easily be added to an existing board.
Erik
NOTE!!!! do not know if the reset poarity of the DS1233 and your chip match DO CHECK. If they do not, there are other 'tripods' that do.
Thank you very much