Wednesday, January 5, 2011

Correctly using PIC in a device disconnected from the PicKit/computer

So I was trying to switch transistors with outputs from the PIC pins, for a project I will post probably tomorrow. The output voltage (digital I/O) was like .6 V when the PIC was running on a 4.5 V source. All that was needed was to tie the MCLR pin high (I used a 15k Ohm resistor). The pin voltage then went to 2.8 V, which was sufficiently high to finally bias the transistor base. I do not know why it is not equal to 4.5 V, but I do not really care presently (EDIT: Ah, it was just a software error). So for basic functionality for a PIC used on a standalone circuit (i.e. taking it off a PicKit dev board), you just need a .1uF capacitor across power supply anode and cathode and the MCLR pin tied high.

Of course, you could just disable MCLR. However my c code compiler for PIC (PICC Lite) does not recognize the bit as MCLRE, or the CONFIG register. So... if you know put it in the comments please.

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