I previously bought an Arduino Uno that came with a store bought/prebuilt PCB and ATMega328p to program it and use the pins. I also have a second ATMega328p that was bought by itself and I successfully bootloaded it to be compatible with my prebuilt PCB so that I could program it.

However, when I try to use either ATMega328p's on just a simple breadboard, neither of them work or output anything meaningful, regardless of how simple a program I make(like the simple LED example given with the Arduino IDE).

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I used these two configurations which should be very similar and it still did not work. I did not include the FTDI serial chip as I wasn't going to use Rx and Tx pins. The 16MHz oscillator, capacitors, and resistors were used as well

How do I use the ATMega328p outside of the store bought/prebuilt PCB?

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    \$\begingroup\$ My first search result in Google is a step by step tutorial with pictures: arduino.cc/en/Main/Standalone \$\endgroup\$ – VE7JRO May 21 '19 at 19:46
  • \$\begingroup\$ Yea that's kinda what I did but without the USB to serial board. I just want the already programmed sketch to execute. The circuit diagrams in that link and the two I posted are almost identical(unless i'm mistake). \$\endgroup\$ – Liro May 21 '19 at 20:02
  • \$\begingroup\$ Do you have a 10k ohm pullup resistor to +5V from the RESET pin in order to prevent the chip from resetting itself during normal operation? Next, verify power and ground connections. Maybe you have a short circuit from power to ground. The 7805 regulator has a shutdown feature if shorted. Of course, diagnosing a problem with a voltage regulator is off topic for the Arduino site. \$\endgroup\$ – VE7JRO May 21 '19 at 20:59
  • \$\begingroup\$ Verify every single connection is correct. If you still can't find the problem, have a look at the crystal oscillator circuit with an oscilloscope and verify a 16 MHz signal. Could you take a picture of your actual setup then edit your question with the new information? \$\endgroup\$ – VE7JRO May 21 '19 at 20:59
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    \$\begingroup\$ @Liro - As already requested in comments so far: (a) Please update the question with the results of the checks recommended on the failing breadboard (e.g. checking the connections) and voltage measurements on the power pins. (b) Please take some in-focus photos of your failing breadboard, so that we can see all the wiring, and add those photos into the question too. Thanks. \$\endgroup\$ – SamGibson May 23 '19 at 17:29

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