SMILEY’S WORKSHOP ☺
■ FIGURE 10. Parts search for DS1307.
■ FIGURE 9. Select the part to import.
and will discuss it later in the article. For now, just think of
this section as a generic discussion on how to import a
part.] Figure 7 show the link to Fritzing’s Online Parts
That led to a Fritzing web page that has a link to the
Fritzing parts repository that led to the DS1307RTC.fzpz that I downloaded. In
Figure 8, I select the import item in the Fritzing Part menu. Then, in the directory
browser window shown in Figure 9, I select the part to import.
Next, I searched for the DS1307 using the (magnifying glass denoted) parts
search facility shown in Figure 10. Then, I clicked on the part and dragged and
dropped it on the breadboard as shown in Figure 11. Notice how the part locks onto
the holes, putting the DS1307 pins into them. When you release the part, the
connections are shown in green (see Figure 12).
What isn’t clearly shown is which pin is pin 1. Figure 13 shows what happens if
we let our cursor hover over a pin. We see that this is the X1 pin, and the next pin is
X2. By referring to Figure 14 which shows an illustration from the DS1307 datasheet,
we see that these are pins number 1 and 2. We can tell this because the drawing has
a circle divot on the IC to indicate the end with pin 1, and that pin is always on the
left in the depicted orientation.
Next, we consult the datasheet illustration of a typical operating circuit (as shown
in Figure 15) to decide what other parts are needed and how we will wire them up.
Let’s be honest here. We
selected the DS1307 in the first
place because there are a
bunch of circuits on the
Internet that show how other
folks have done this design, so
we will be highly influenced by
those observations. [One thing
to note is that I used a 0.1 µF
bypass capacitor that isn’t
shown in a typical circuit. I do
this because I’ve had enough
experience to know that these
help prevent digital glitches.
Although we might get by
without it, they are cheap and ■ FIGURE 13. Identifying pin numbers.
■ FIGURE 11. Drag it to the breadboard.
■ FIGURE 12. Connections
shown in green.
August 2012 55
■ FIGURE 14. DS1307 pins