PIC16F877A interface with computer

[jonil22]

Hi,

I got a question to ask . Why can pic16f877A be connected directly to the computer without going through MAX232 ? I tried it and it works. Plz help me answer that question. Thanks.

[Melanie]

Because it can and it was your lucky day.

The tollerances on modern RS232 interfaces are very wide... and the PIC is resilient. With your PIC parked next to your PC with a few feet of cable yes it'll probably work - but there are no guarantees.

RS-232 is capable of being driven to 1km without Line Boosters... there is no way your PIC will connect directly at that distance - or even one-fifth of that distance.

Try connecting to an old Tandy TRS-80, Superbrain, Zenith Z-89 or DEC PDP-8 and tell us if it works...

[skimask]

Try connecting to an old Tandy TRS-80, Superbrain, Zenith Z-89 or DEC PDP-8 and tell us if it works...

TRS-80 Color Computer 2....YES! Straight across, although I did put in a 100 ohm series resistor just in case.
Thru the cassette port. Wrote some bit-banged 300bps code using EDTASM+ for the ol' 6809E. Used the CoCo2 basically as a 'dumb terminal'...
Of course, I've since gotten smarter and quit writing 'dumb code'
I've still got the CoCo2 and the cassette with the code on it, and the EDTASM+ cartridge if anybody wants to modify the code.

[Melanie]

You're showing your age Ski... I hadn't been born yet when the TRS-80 hit the streets... but it's good to know that it works with a PIC for when I get to be curator in some museum somewhere... and need to demonstrate that our ancestors once walked upon the earth with brains no bigger than 8kb... (OK it probably had more than that, but there was always that abomination of design called a Commodore PET).

[skimask]

You're showing your age Ski... I hadn't been born yet when the TRS-80 hit the streets... but it's good to know that it works with a PIC for when I get to be curator in some museum somewhere... and need to demonstrate that our ancestors once walked upon the earth with brains no bigger than 8kb... (OK it probably had more than that, but there was always that abomination of design called a Commodore PET).

I started off with an MC-10...but before that, I didn't have the manual dexterity to type anything but a bunch of pudding all over my face....