PIC16F877 + ICSP

Started by Paul_Lav March 8, 2004
I am using a PIC16F877 and am programming it using ISCP and using programmer EPIC Plus. It has been working, but now i have added more to the board it has stopped. I get an error saying "Code programming error at 0000". I think the cause it i have a pull up resistor on PORTB,3 and this is the Low Voltage Programming Pin. I am getting funny results with different combinations of Configs, Low Voltage Program Enable, Flash Program Write Enable and different combinations if i dissconnect PORTB,2 + 3 + 4. I can get it to work with only PORTB,3 dissconnected, but still get some weird results, the pic won't program when i first turn it on, but does if i try again, without changing anything? An idea i have had is i could use the PORTB, internal weak pull ups. Would this work? Or i could use a transistor and take the PORTB,3 pin low when programming, i could tap into the transistor that puts the high voltage on pin 1, Clear Pin. Also what have PORTB,2 + 4 got to do with programming as i apprears that these alter things? Or will it just all be to do with PORTB,3?