Hardware Reference
In-Depth Information
Figure 4-15.
Finished breadboard
5.
Now as per the data sheet of your LCD, or if you're lucky in my case the markings on the
back of the LCD, connect the shift register pins to the LCD as listed in Table
4-4
.
Table 4-4.
Mapping of PCF8574AN pins to LCD pins
PCF8574AN Pin
LCD Pin
P0
DB4
P1
DB5
P2
DB6
P3
DB7
P4
RS
P5
RW
P6
E
6.
Don't forget to connect the LCD's logic Vcc and GND. If your LCD has a backlight don't
forget that too. In my case the backlight is 5 V and can be accessed via pins 15 and 16.
7.
As long as the power is off to the LCD and the shift register you can connect it to the
Raspberry Pi's I2C bus. Connect pin 15 (SDA) on the PCF8574AN to the Raspberry Pi's
P1-03 header and connect pin 14 (SCL) on the PCF8574AN to the Raspberry Pi's P1-05
header. If you are worried about letting the magic smoke out of the Raspberry Pi, just
power it down while you make the connection.
