Programmer configuration...

[mcbeasleyjr]

I wasn't sure where to post this so I thought I would post it here... I seem to be having an issue with my PICs receiving my programs throught the melabs programmer... I write all my code using PBP in Microcode Studio... I then load the program's hex file into the melabs programmer with the following settings...

Oscillator - HS (20MHz Resonator)
Watchdog - Enabled
Power-up Timer - Disabled
Brown-out Reset - Enabled
LVP - Enabled
Flash Program Memory Write - All
Code - Not Protected
Data EEPROM - Not Protected

I am using the U2 USB programmer.

After the code is written, the PIC will not operate the way it is supposed to. If I write a simple Blink program, the PIC isn't blinking LEDs at all. I've checked all my wiring and double checked my code. The only conclusion I can come to is that I'm doing something wrong with the melabs programmers configuration as I write the code.

PIC16F877A

Any input is appreciated.

[rsocor01]

Try,

LVP - disable

Robert

[mcbeasleyjr]

Sorry it has taken me so long to get back to you. I've been busy with work and haven't had much of an opportunity to work on projects at home. Now that I've found the time, I have tried programming a PIC16F877A with LVP disabled and it is working like a charm. Could you explain to me why a USB programmer isn't using LVP? I also had an error in my code that was causing an unrelated issue. That has been resolved as well. I thank you for your speedy response to my initial problem.

[Sneaky-geek]

Hi mcbeaslyjr,

Go to MEL's website and root around there for more information. Also try to look it up in the MEL U2 programer manual. There is a good explanation there.
It has to do with some chips PROGRAM at lower voltages ie 3.3 V. Also did you somehow accidentally TURN on LowVoltageProgramming?

Sneaky-geek

[mcbeasleyjr]

Lol it is quite a possibility. Most of the time I'm working on this stuff I have my two small kids playing nearby... so it's quite easy to get distracted.

[rsocor01]

Could you explain to me why a USB programmer isn't using LVP?

This next quote is taken from the Melabs web page, http://melabs.com/support/icsp.htm

4. Make sure the "low-voltage programming" pin is pulled to ground. Low-voltage programming is not used by melabs programmers and should always be disabled in the configuration settings. Even so, the low-voltage programming pin (labeled PGM or LVP) should be pulled to ground when programming. If it is left floating or in a high condition, it may interfere with the programming process. We use a 100K resistor to pull the pin low when designing a board for ICSP. For most 16F series parts, RB3 doubles as the PGM pin. On 18F series, it is usually RB5 that needs to be low. Notable exceptions are the 16F62x and 16F64x family, which need RB4 to be pulled low.

Robert