Hello, im working with 80c552 yC. On the Board is also an SRAM (xdata). To keep it's data after disconnecting the external power supply, i connected it with a battery. It works fine... Inside the SRAM, i have an Array of unsigned char* to save "Strings" in it. Now my problem: If i cut the external power supply and connect it again, some Strings in the array have very strange characters inside. This happens sometimes, not all the the time. I checked the software, but there is everything ok. Could it be, that the processor does some undefined things if the exrternal power supply breaks down and writes some bits into the SRAM on undefined adresses? Can anybody help me solving that problem? Andre (Germany)
connected it with a battery. ... If i cut the external power supply and connect it again, some Strings in the array have very strange characters inside. are you sure the battery gives enough voltage? the 552 is quite hungry. For best data intergrity the battery and the external power should be connected through diodes prior to the regulator. Erik