Page 37 - Making PIC Microcontroller Instruments and Controllers

MlcFocHlP IECH OIOGYS Plc i6Fa77Ar A DESCRIPIIoN
26 UNDEBSIAI{DING oF THE McU

Pin 24 POBTC.5 Clock chips

Pin 25 PORTC,6 Transmil seria communications R5232C
Pin 26 PORTC.T Receive seria comnrunications as232C
Pln 27 POBTD,4 LCD and LED barcraph
Pin 28 POBTD.5 LCD and LED bargraph
Pin 29 PORTD,6 LCD and LED bargraph
Pin 30 PORTD.T LCD and LED bargraph
Pln 31 Logrc grouno
Pin 32 Logrc power
Pin 33 PORTB,O feypad inputs
Pin 34 PORTB,]
Pin 35 PORTB.2
Pin 36 PORTB.3 Proglg device Keypad inplrts
Pin 37 PORTB.4 Keypad rnputs
Pin 38 PORTB.5 Keypad inpuis
Pin 39 PORTB.6 Progr'g device Keypad inpuis
Pin 40 PORTB.T Proglg device Keypad inpuls

PORTB lincs set as inputs can be plrllcd up ioternally wi|h a soti\rare instruclion
Inreffupis can bc gcneraied by changes on PORTB lines when lhey arc progranned to

USIT{G THE A-TO-D CAPABILITIES OF THE PIC I6FA77A
You can make a number ol basic nreasurements wilh thc I-AB Xl board by using its
analog to digital conversion capabilitics. The resolution oI thc conveNion can bc Il or
10 bits. Still highcr resolutions are av.rilable i[ wc Lrse ICs that go in cnrpty socket U6.
The measuremenls wc make can be used to delerninc the foliowing:

& Resistance
& Capacltance
X Voliage
e Frcquencl' (This is, ofcourse. not an.^-to-D function.)

Resislancc is determined by measuing how long it takes a rcsistor to discharyc a
is as accuralc as the value of the
capacitor thal has just been charged. The mcasurement
capacitor The measurcmenl pafameters lnay nccd !o be adjusled in rc, lime to get a