Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

some source codes for PIC16F84, what's portb pullup?

Status
Not open for further replies.
S

simonwai999

Advanced Member level 4
Joined
Jun 30, 2008
Messages
114
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,296
Activity points
2,175
some codes

hi
i saw some codes like these for pic16f84
Code: 
 		ORG	0
PowerOn		BSF	STATUS,RP0		;Select file bank 1
		MOVLW	H'00'
		MOVWF	TRISB			;Set all PORTB bits as outputs (display driver)
		MOVWF	TRISA			;Set all PORTA bits as outputs (will be inputs in future version)
		MOVLW	B'11010111'		;Turn off PORTB pullups, prescaler to TMR0, 1:256 scaling
		MOVWF	OPTION_REG

what is portb pullups?
Does it mean portb is connected to vcc and this sets it to the vss?
thanks
 

some codes

Port pull ups are can be enabled so if you are using the lines as inputs, you dont need to add external resistors to pull the lines up to Vcc.
You cant have floating inputs, pull ups hold them in a high state. They are weak pull ups, sort of like adding a 220k resistor to the line.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top