Step 3: Prepare the DCF77 receiver
Required parts:
Placing the parts:
1*220 Ohm
1*3.3 volt zener diode
pin header and jumper (optional)
The zener diode and the 220 Ohm resistor make a voltage divider to produce the 3.3 volt that the
DCF77 receiver requires.
The pin header and jumper are optional. They switch what is connected to the PON pin on the
receiver (that can be used to put the receiver to sleep). If you attach it to ground, then the receiver
will stay on permanently. Alternatively, you can connect it to pin D13 of the ATMEGA328-MCU, so
you can put the receiver to sleep whenever you want.
The pin assignments on the board correspond to the receiver by Pollin. Other receivers might
require extra circuitry which can be placed in the prototyping area of the board.
If the receiver has a good signal then the yellow LED will blink once per second (but a shorter blink
than the green LED). A DCF77 receiver can take up to a half an hour before it is ready!
3.3 v
olts fr
om
the v
oltage divider
Gr
ound
Gr
ound
Da
ta
PON
PON
These two
pins are
connected.