Author Topic: why PortA.4 of PIC16f84A wont output? (Read 1080 times)

mon2jacko · « **on:** November 03, 2009, 03:58:21 PM »

im having trouble of having an output on porta.4 of pic16f84a. is it possible to have an output on it? i have an project that needs 8inputs and 5 outputs so i decided to use the portb as my input and porta as an output. MY QUESTION: IS IT POSSIBLE TO HAVE AN OUTPUT ON PORTA.4? PLS HELPPP....

THNX!

Philippine Electronics Forum · « **on:** November 03, 2009, 03:58:21 PM »

0b00000111 · « **Reply #1 on:** November 03, 2009, 04:00:06 PM »

open-drain po siya

Philippine Electronics Forum · « **Reply #1 on:** November 03, 2009, 04:00:06 PM »

zer0w1ng · « **Reply #2 on:** November 03, 2009, 04:02:46 PM »

RA4 has open-drain output.
Meaning it can only sink current and not source it.
If you want a + output, put a pull-up resistor to the VDD on this PIN.

You could read this info in the PIC16F84A's datasheet.

Philippine Electronics Forum · « **Reply #2 on:** November 03, 2009, 04:02:46 PM »

Mayalin22 · « **Reply #3 on:** November 03, 2009, 04:06:00 PM »

o kaya swap ka ng isang pin sa portb.

A4 = input
B? = output

Philippine Electronics Forum · « **Reply #3 on:** November 03, 2009, 04:06:00 PM »

updated · « **Reply #4 on:** November 03, 2009, 04:07:15 PM »

tama si master7 as always

open collector po kasi ang porta,4. so pede m nmn gamitan ng pull-up resistor n 10K. or lagyan m ng led sa output at vcc.

tama ba ako master7?

Philippine Electronics Forum · « **Reply #4 on:** November 03, 2009, 04:07:15 PM »

your most RIDICULOUS man :) · « **Reply #5 on:** November 03, 2009, 05:22:15 PM »

Ano po ibig sabihin ng open drain?

Mayalin22 · « **Reply #6 on:** November 03, 2009, 05:26:32 PM »

open drain or open collector

If the output device is a MOSFET the output is called open drain and it functions in a similar way.

blastronics · « **Reply #7 on:** November 05, 2009, 05:02:54 PM »

read mo yung data sheet nung PIC reagadin PORTA.
this default nun is an analog input kaya isa din yun sa dahilan bakit di gagana.

may initialization muna yun para maging DIGITAL PORT.

Load ADCON1 with 0x06

in summary, read po ng data sheets...

Mayalin22 · « **Reply #8 on:** November 05, 2009, 06:26:26 PM »

sister la ata analog ang F84

blastronics · « **Reply #9 on:** November 06, 2009, 09:15:51 PM »

Quote from: c0♂Lët on November 05, 2009, 06:26:26 PM

sister la ata analog ang F84

OOOOOPS!!!

Im reading PIC16F876 data sheet....

But the problem also excist on these device.. PORTA 4 wont have any output...

Mayalin22 · « **Reply #10 on:** November 06, 2009, 10:33:05 PM »

me output pa din open drain nga lang... open drain output are good for 1 wire communication specially kung maraming device ang nakakabit.

Philippine Electronics Forum · « **Reply #10 on:** November 06, 2009, 10:33:05 PM »

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