Matthew 1. If your programmer supports 16C84 you can (probably) program 16F84s using the 16c84 setting with the protection bit setting reversed (ie use "protected" when you want "unprotected"). 2 Is this the only program you have tried or the only one that won't work? If this is your first program it would be advisable to try a VERY simple program that eg just flashes a LED first to show that the basic system is working. A complex programme that doesn't work can hide more fundamental problems. 3. If the program is all working but the hardware is not functioning then the following MAY be your problem (but Murphy says it probably won't be.) I am unaware of the particular circuit you are using (what is the app note number?) but many people on this list say they have used RS232 straight into a PIC pin via a series resistor and have said that this worked for them and that the PIC protection diodes "catch" any voltage overswing. However, this method of input protection is not guaranteed in the datasheet. Generating substrate current via the protection diodes can conceivably cause unexpected results and in my experience, it did. I used a series input resistor for RS232 receive with a 16F84 and had endless problems due, as it turned out, to the current into the protection diodes. This can be overcome by either placing reverse schottky diodes (eg BAT85) to supply and ground from the input pin or by splitting the input resistor into 2 and using 2 silicon diodes from the midpoint to ground and supply. Both schemes stop the protection diodes conducting during normal use. -----Original Message----- From: Matthew >I have the "PIC 16CXX Applications Handbook" and I'm trying to run the >rvc232.src on a 16c84 and I can't get it to do anything. I'm using >SPASM to compile it which I also purchased from Parallax. >I've made the code change for a 22k ohm resistor. I've also marked out: >;reset begin >Changed the pic16c54 too pic16c84 >Compiled with: SPASM rcv232.src /s >I've used two different programmers: >picstart 16B1 and the ITUtech programmer. Both seem to program the pic. >Changed the cfg bits to XT, watchdog off >I'm using a 4MHz osc module rather then a crystal, same thing but >easier, going to OSC1 pin. >I've tried communicating with two different computers running the >Qbasic program in DOS. >The voltages are correct powering up the chip. I've tried two >different pics. I have 3 pic16f84's but neither of my programmers >support them. How convenient, I just spent 80$ on the picstart >programmer. >The LED's seem to flash once when the circuit powers up but that seems >to be the end of it. I've checked the osc with a scope on the osc1 >pin and its good. >Any suggestions? Please.... > >Would using a Parallax programmer make things go any easier?