Anaximander
New Member
I put my PIC18F2550 in my solderless breadboard and connect it up to my JDM programmer. Oddly, the programmer's LED that indicates if its managed to power the chip doesn't go on. I assume that the PIC requires too much power, so I connect it up to a 5V supply. The porgrammer's LED goes on, and the chip programs properly.
The program is a simple one that just toggles all the output pins on PORTB. After much messing around with PBANEN and MCLRE config registers I finally get it working. An LED connected to a PORTB pin flashes. But what's that smell? It's the 'overheating component smell',a nd sure enough, the PIC is painfully hot to touch. Further experimentation reveals that the PIC is drawing about 330mA of current, greater than the 'absolute maximum ratings' given in the datasheet (Not very absolute, it seems).
I try another PIC18F2550, and that programs fine, and runs at a non-flesh-searing temperature, drawing a more reasonable 60mA. Clearly I've managed to damage the first PIC somehow. It looks like there's an almost-short in there somewhere. But what could have caused that, and what could fix it?
The program is a simple one that just toggles all the output pins on PORTB. After much messing around with PBANEN and MCLRE config registers I finally get it working. An LED connected to a PORTB pin flashes. But what's that smell? It's the 'overheating component smell',a nd sure enough, the PIC is painfully hot to touch. Further experimentation reveals that the PIC is drawing about 330mA of current, greater than the 'absolute maximum ratings' given in the datasheet (Not very absolute, it seems).
I try another PIC18F2550, and that programs fine, and runs at a non-flesh-searing temperature, drawing a more reasonable 60mA. Clearly I've managed to damage the first PIC somehow. It looks like there's an almost-short in there somewhere. But what could have caused that, and what could fix it?
