Testing the ATMEGA328-MCU (external power supply)
Required parts:
Placing the parts:
1*power Jack
1*voltage regulator
1*blocking diode
2*100 nF
2*100 µF
Solder the green and yellow LEDs plus their 1
kOhm resistors just like you did the power
LED. Here too, place the longer leg of the LED
in the hole marked red in the diagram. These
LEDs and resistors must be soldered on
regardless of which power source you use.
Make sure to align the voltage regulator so that its metal plate will lie on the rectangular solder
plate. Face the side with writing toward the real time clock area and face the metal part toward
the open source hardware logo.
The large capacitors (100 µF) have polarity. The leg with the minus sign goes in the hole with the
mark (The two capacitors‘ negative poles face each other). There are two holes for the other leg
to handle capacitors with different leg spacing.
For testing purposes, when you use external power (jumper to the WALL position) then the
yellow and green LEDs will quickly blink three times.