I don't know if its a typo but the 10k resistors on RB6 and RB7 are in series to isolate external circuitry. See 32028a, 91016b, 51474a etc.
George
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Re: I'm at a loss
I don't know if its a typo but the 10k resistors on RB6 and RB7 are in series to isolate external circuitry. See 32028a, 91016b, 51474a etc.
George
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Re: I'm at a loss
The 10k resistor is part of the pull up resistor of the optocoupler.It's a 5 volt supply through the 10k and then to rb 6. Same setup for rb7. Rb 6 and 7 are driven high, then pulled low when triggered. Standard setup.
Should I apply power to the circuit when programming it, maybe?
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Re: I'm at a loss
circuit diagram?
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Re: I'm at a loss
Why don't you use the internal pull-ups in your chip? The following is from the melabs webpageOriginally Posted by ERMEGM
http://melabs.com/support/icsp.htm
From the website
1. If possible, dedicate the Programming Clock and Data pins to ICSP. If you must also use these pins for other purposes on your board, some thought should be given to the type of hardware that is connected. The best case is to use the programming pins for normally-open, pushbutton inputs. As long as you don't push the buttons while programming, the switches won't affect things at all.
If loads are connected to the clock and data lines, they must not interact with the clock and data signals. Capacitive loads will cause problems. High-impedance loads are usually ok. LEDs with current-limiting resistors are less desirable, but usually don't cause problems.
You should always prototype and test the ICSP connections before sending your PCB design out for fabrication.
"No one is completely worthless. They can always serve as a bad example."
Anonymous
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Re: I'm at a loss
Well, I'm certain that the chip has to have power supplied during program and I'm certain you're going to have to pull the MCLR pin high or disable it for the chip to work.
Since there really isn't a standard installation all bets are off as to what those pull ups will do. The pins have to change state to transfer data and the pull ups may prevent that from happening. I've taken to putting a switch to disconnect the rest of the circuit if I must use the ICSP pins for other purposes. An easy way to find out would be to unsolder the resistors and attempt programming. That would be the one way you'll know if that's the issue.
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Re: I'm at a loss
Some boards isolate the 2 programming pins via jumpers while performing ICSP.
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