Can i use an Actual Computer Serial Port to Upload Sketches ?

Hi there folks,

okay i dont think this is possible but a friend is wanting to do this and im out of ideas and my Google-Fu isnt bringing up much !

I want to use an actual Old computer's Serial Port to upload sketches to a breadboard Arduino Uno which works nicely but am a bit stuck as we have an almost impossible challenge !!!!

The challenge is, we want to only recycle and gather parts for this project from old devices, de-solder anything we need to be able to upload via the Serial Port on an old computer.

Now, ive already gone to say that the serial port is 12v (i think, lol) so we would need a voltage regulator and also a way to get the serial to talk to the Arduino via a TTL to Serial IC and this is where is all falls down.....

What kind of old devices are there out there that would have an IC inside for enabling us to convert TTL to serial for uploading sketches ?

Ive personally done a full few weeks searching for devices using the MAX232 IC and not even come up with ONE old device!!!

Anything will do as long as its an old device and we can interface it with the Direct serial port connection on an old PC's serial cable !

Trying to think green here but need help lol !

Any help towards this would be so very greatly appreciated and a great many thanks in advance ! ! !

will this help?

Wow thanks for the fast reply !

Im not sure, has this been tried and tested by any chance ?!?

i think ive got the components to test this but annoyingly i dont have an old computer with a serial port lol !!

And the problem is my friend doesnt have many components to try this with as he strictly only cannibalises old tech for his projects and only buys the atmega chips, breadboards and stuff you cant get from old tech so he cant afford to be wrong with testing a new way out :wink:

Your circuit diagram looks quite nicely drawn, did you do this yourself or is there a link from somewhere on the internet with more info about it, just for a bit of reading into it lol ?!!?

That's the interface from the original Serial Arduino. So yes, it should work.

annoyingly i dont have an old computer with a serial port

Then why do you say so many times that the download has to be via "an actual Old computer's Serial Port "??

There seems to be a conflict between your desire to achieve this with the old junk you have lying around, and the fact you don't appear to have the electronic skills required to do that. You need to either make, find or buy an RS232-to-TTL serial converter. You can buy them retail for practically the cost of postage so I don't really understand the reluctance to spend money on parts (will you be making up your own cables from junk too?) but if you're determined to make your own the circuit is not complicated. You could even make it from recycled electronic components if you don't mind wasting hours desoldering transistors and resistors to save a few cents.

Just how old is this 'old PC'? RS232 ports stopped being a standard on new PCs several generations ago and these days anyone needing an RS232 port is more likely to need a USB-to-RS232 adapter to achieve that. I don't know which part of the world you are in, but here in the UK the value of a PC goes negative after relatively few years (the disposal cost exceeds the reuse or recycling value) and it's easy to pick up a rubbishy old PC at zero cost. Are you using a physical RS232 port for the sake of it, or do you actually need to?

Good evening to you Peter & crossroads !

Thanks so much for your advice

Yaa im in the UK too lol, only just learning electronics at present but mind is torn between my daily pain levels of my disability so im finding it pretty hard to concentrate on learning electronics but trying my very best to do so this time, been learning all year so far and doing pretty okay so far, just need some help on how the old boys used to do this in the times of the Old Serial Arduino Boards (DB9 Connector on old computers to Arduino Board, @ crossroads too, sorry, this is what i meant !) on earlier Arduino Boards !

But im actually trying to help out a friend who has an old computer and has an Atmega1284 setup on a breadboard but is hell bent on only using components found in old junk, so hey ho, if thats what he wants to do, im just seeing if there's any old devices out there that would yield an RS232 to TTL serial IC, ive already recommended that he just buys the MAX232 IC (i think this was used on the very early arduino boards?!?) but this one's adamant that he wants to use the DB9 serial port on an old computer and only reclaim IC's and what-not from old tech !

CrossRoads:
That's the interface from the original Serial Arduino. So yes, it should work.

Ahh i see, lol, yaa didnt know as im just learning the world of Arduino so will put this into practice ! looks like a great simple little circuit !

Thanks again !

By the way, by meaning an old computer serial port i meant the DB9 connector on old computers ! Sorry still very much a beginner in the world of arduino so still learning its roots !

Yes, follow the old Serial Arduino scjematic then

!!! PERFECT !!!!

Thanks crossroads, this is officially SOLVED BEAUTIFULLY !!!!!!
Just what we were after, no IC's, no complications in finding old tech with the possibility of an RS232 IC in it, just a bunch of resistors, connectors and transistors lol ! (and a VR lol)

Thanks to everyone for all your help in so quickly solving this !

Now i want to track down an old computer XD

offtherails2010:
this one's adamant that he wants to use the DB9 serial port on an old computer and only reclaim IC's and what-not from old tech !

That's all well and good, but he doesn't actually seem to be doing that. Recycling old junk is suddenly far less admirable when all he's really doing is providing the junk and making it your problem to figure out how to make use of it. The circuit to convert RS232 to TTL is pretty simple, especially given that you only need a simplex connection, but the fact he hasn't even managed to find that suggests to me that actually he's put no effort at all into this. And given that he doesn't seem to be using this as a learning exercise, and seems to be asking you to do if for him just to save about $2 for an off-the-shelf part, what's the point of this exercise?

But hey, they're keeping busy and not out in the street playing in traffic 8)

That's all well and good, but he doesn't actually seem to be doing that. Recycling old junk is suddenly far less admirable when all he's really doing is providing the junk and making it your problem to figure out how to make use of it. The circuit to convert RS232 to TTL is pretty simple, especially given that you only need a simplex connection, but the fact he hasn't even managed to find that suggests to me that actually he's put no effort at all into this. And given that he doesn't seem to be using this as a learning exercise, and seems to be asking you to do if for him just to save about $2 for an off-the-shelf part, what's the point of this exercise?

Ahh yes, now that would be my gullible side lol !

but ive learned something about the rich history of from what simple components an Arduino board evolved from and loving every stumble, hurdle and triumph - especially actually making these circuits ! Ive been making up real simple PCB's and trying out SMD soldering too but just need to spend more time studying the theory and equations side of electronics, although im severely limited to how much i can do everyday, its such a bad joke....

Anyhoo i suppose the moral of this story is that i dont mind helping out and in the end i learn something from it that will hopefully stay with me for a long time and something i can now refer back to when i get my hands on some old tech ! Thoroughly bookmarked lol !

Once again thanks Peter :wink:

CrossRoads:
But hey, they're keeping busy and not out in the street playing in traffic 8)

LOL !

or 'with' traffic (in my driving years lol !)