Issues with ISP/SPI on a circuit design

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I was wondering if some experienced guys could look at my circuit and maybe help me figure out why when I connect my avr dragon to try and program my atmega328p incircuit it won't read the device and I see a large current draw (100ma)?

 

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BOTH Grounds, Pin 8 and Pin 22, need to be connected to Ground.

 

Make sure the Cin and Cout caps on your 7805 meet the data sheet recommendations for the manufacturer's voltage regulator you are using.

 

Make sure your cable to the Dragon is not wired up-side-down and/or backwards.

 

JC

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I would also make sure the cable from your dragon isn't to long aswell. Double sheck your load caps on your crystal 33pf seems high for a 8mhz.

This is has nothing to do with the problem, but I believe it's better practice to switch your + line instead of the negative.

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Ill try swapping those caps out. The cable is only like 6 inches off the dragon to spi port. If i pull the chip out of circuit and put it on a bread board to only program it it works fine. And switching the power on The positive side is probably a good idea. Ill change that. Still do t k ow why i cant program in circuit though. The chip functio s fine once programmed and placed in the circuit...

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I commend you on your schematic activities.  Today, too many folks are too lazy to draw the actual connecting wires & their "schematic"  becomes more like an excel netlist, rather than a visual representation of what gets connected to what.  Seeing the connections lets us easily tell what is misconnected, overlooked, or problematic.

 

Of course, like any fine wine or food, too much can become excessive.  You'd do your self a BIG favor by using the ground symbol everywhere gnd is needed.  No need to have one wire traipsing all over the place & clogging up the drawing.  That is where a symbol shines.  It is not for connecting one point to one other point 2 inches away.   Draw your opamps as opamp symbols, it will make understanding your circuit far easier & cleaner.  

 

As an example,  why not connect your 7805 to gnd so that it can function as a regulator?  Using the gnd symbol would make it more apparent that it is missing.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Thu. Mar 14, 2019 - 02:11 AM