Page 203 - Making PIC Microcontroller Instruments and Controllers

NOTES O USII{G SEVEN.SEGMENT DISFLAYS

c6
c7

B3

84
B5
B6
97
l]fjEr{ttlal9;9..i One way of wiring for the seven-segment displays as

subroutine so it can be callcdby a
The display rouline is wrilten as a self-contained
relativelyfiequentinrer.rpltokccpth.3djsplayalivewhilealongandcomplicatedpro
gram goes about doing ils work.
Program 15.2, with a bit more code. rcplaces *rc code lbr the LCD in the original
program. The complete program is listed after the wiring diagrams and some seven-
segment rclated notes that follow

Notes Usins Seven-Sesment
on
Displays

The lighting of the displays is somewhat like the reverse of scanning a keyboard. The
segnents thal are lit represent thc rcverse oflhe keys that were pressed. In eilher casc,
the scan idenliljes eithcr a displayed set of segments or a key- Most scanning roulincs
serve similar lunclions and arc implcmcnted in this same way.
Lefs wite a short routinc to light all the segments in a seven-segnent display onc
segment at a time. Assume thal the scvcnscgments and the deci mal point are connecled
a common arode
to PORTB. The common line is attached to PORTA.I. Lct's assLrme