Page 262 - Making PIC Microcontroller Instruments and Controllers

260 A DUA! THERiIOI'ETER IIISTRUiIENI

instrument.
lffitr!|tdf* Dual thermometer

Analog signal0 PORTApin 0
Analog signal I PORTA pin I

Analog signal 2 PORIA pin 2
Analog signal3 PORTApin 3
PORTA pin 4 Pin is not for analog use! (see Table 18.2)

Analog signal4 PORTApin 5
Analog signal 5 PORTE pin 0

Analog signal 6 PORTE pin I
Andlog signal 7 PORTE pin 2

ff you use the following ADCIN instruction:
tDcrN 5. var_(rE
you will need to have the signal connected to pin E0 and the value read will be placed
in variable VAL UE. The number (5) in the instruction is a relerence to the iifth analog
signal number in these eight analog input pins, totP1NA.5.
Since most projects require a liquid crystal display, and we oiten use the lines on
PORTE to control the displat the five lines on PORTA will be the ones most commonly
used as analog inputs. (Howeve! all three ljnes on PORTE can also be used as analog
inputs if the LCD conuol tines are assigned to another poft with the DEFINES, or if you
are not using the LCD at all.)
As with any PIc microprocessor with analog capabiljties, the 16F877A micro-
prccessor comes up in the analog mode on reset and sfartup. A number of the analog