Need basic rs232 cable schematic for boarduino

i cannot get a usb adapter but i have a serial cable here but im not entirely sure on the schematic for the cable , apart from pins 2, 3, and 5.. what other pins are needed (like reset, +5v) and how is it constructed.. please need help. my old arduino board is faulty and i cant use it to upload to the boarduino's chip :(

BongMaster,

Let me understand: you need a serial (DE-9) cable to connect your computer to Boarduino 6 pins in line connector?

The Boarduino 6 pin connector is FTDI USB TTL standard cable, right?

So the serial to 6 pin cable will not be easy to make. You have to make the serial circuitry on it, and I'm not sure it will work.

Wait a little, I'll draw it for you...

ok thnx. i discovered that there was something wrong with my dec board when i tried to upload a sketck onto the new chip… it wasnt communicating and i though it was the old chip… now i find the board isnt communicating with the chip at all cos the rx tx led’s wont blink and pin 13 wont light at all… so something is wrong :frowning:

the boarduino works fina as far as i can tell. but i need to load a sketch onto it to be 100% and with no working ftdi im screwed…

also i dont want to try my parallel cable on the new chip in fear of buggering it up :frowning:

Well,

I already did it. But I didn't found a Boarduino Schematic, only FTDI cable schematics, and so I'm not sure about Boarduino connections. I'm "almost" sure about this cable... If you wanna try, [u]it's at your own risk.[/u]

Perhaps at Lady Ada's Forum someone could help you, being really sure about this cable. I saw only an answer on its forum, saying that a Serial to TTL cable can be used instead of USB to TTL. http://forums.ladyada.net/viewtopic.php?t=4569

Good luck. [edit]I forgot: the leds and its resistors are not necessary.[/edit]

thnx :slight_smile: i’ll look into it today :slight_smile: i hope i can use this and have the parts needed :smiley:

(edit) Dang the only transistors i can find are 559 and 549 not 557 and 547 :frowning:

what trade offs can i do with this schematic to suit the components i have? i havnt even tried to look at what resistors i got and dont know how to identify some caps or diodes :frowning:

man im a total noob… most of my stuff is harvested from old junk u see…

i appear to only be able to find a couple of transistors that say c559c and c549c, i have the diodes, and i hope i have the resistors :)

will those transistors be ok and what changes to the schematic will they require? or do you have any other suggestions?

i am also unsure how to identify the100n cap in the mixed caps i have..

I think those transistors should be OK, but you'll need to check the datasheets to make sure you get the pin order right - just make sure the B's, C's and E's match up.

100nF capactors will be labeled either:

100nF 0.1uF 104

thanks :) i'll get back with results or more noob questions :D

LadyAda seemed to like the schematic :)

BC549 http://www.ortodoxism.ro/datasheets/motorola/BC549C.pdf BC559 http://www.ortodoxism.ro/datasheets/motorola/BC560C.pdf BC547 http://www.ortodoxism.ro/datasheets/motorola/BC546B.pdf BC557 http://www.ortodoxism.ro/datasheets/motorola/BC557A.pdf

All 4 have the same package (it means same terminal names and positions). Positioning the transistor to read the printed name on it, you have from left to right: collector, base, emitter.

100nF caps can be labeled as µ1J63 or µ1J63 too.

1N4148 have a glass coat, red, and a black stripe that indicates catode. But you can use any other fast switching, or small signal diode. There are many.

1K: brown, black, red, (gold or silver) 4k7: yellow, violet, red, (gold or silver) 10k: brown, black, orange, (gold or silver)

And use the 10µF electrolitic cap with plus to GND.

I'm not sure if the C4 (100nF) is already soldered on Boarduino. Follow the pin 2 wire on board. If it connects directly (or through bridges, or through reset switch internal short circuit) use the C4. If the wire takes you to one 100nF cap, you don't need another one on your adapter, and use a wire directly from serial pin4 to TTL connector pin2.

thnx :) i believe i have all the bits now :) would it be possible to have the Eagle files so i can work out a small pcb design for this?

it would be a big help :)

and thnx so much for this :) i hope it works :D

Test it before, on protoboard.

The circuitry is simple, you can use perfurated board to make it.

But if you want to make a PCB: http://www.4shared.com/file/35500421/9fb8c14a/SerialtoTTLCable.html (Edit: new file and adress since Bongmaster could not open old version)

The .brd file has only the components.

The files wont open :( eagle keeps coming up with an error message saying they could be damaged or something. same for both of them..

downloaded them several times to be sure.

YaY it worked! :D thnx so much :) this mess of wires and componants on my breadboard actually uploaded the blink sketch ok :D i had to manually reset tho for it to work.. dunno why, will look into it :)

i will try and make a pcb to hold it all, i had to redraw the schematic and mess about til i got a good enough single sided layout. i hope i can make it without etching :S i have no etchetant :D so i'l have to engrave it or something. unless anyone knows a way to etch with household stuff :)

thanx again :D

BongMaster,

I edited the previous post: the file in the link now can be opened.

I forgot to say: if you want to use the cable only to upload sketches, no problem.

If you want to use the cable to transfer data to/from computer, you should use a bipolar electrolitic cap at C8. It's not critical (cable will work if polarized cap is used), but the correct component.

And I told you: I don't know nothing about Boarduino Schematics, only by pics, so I really don't know why Auto reset is not working. It doesn't work with C4? With wire instead? both?

BongMaster,

I edited the previous post: the file in the link now can be opened.

I forgot to say: if you want to use the cable only to upload sketches, no problem.

If you want to use the cable to transfer data to/from computer, you should use a bipolar electrolitic cap at C8. It's not critical (cable will work if polarized cap is used), but the correct component.

And I told you: I don't know nothing about Boarduino Schematics, only by pics, so I really don't know why Auto reset is not working. It doesn't work with C4? With wire instead? both?

tried both ways.. and hit the reset button at the right time on the last attempt and it worked fine :) its a small price to pay to have to manually reset tho :) now i gotta make it more permanent :S

thnx again I'll re download the files

(edit) I see why the autoreset didn't work after i looked at the boarduino schematic again. i moved the rts wire from pin 2 on ure schematic to pin 6 where the reset line is on the boarduino and that worked :D seem pin 2 is null in this :)

There's an inexpensive kit that uses an inverter here:

http://moderndevice.com/connect.shtml

Schematic is in the instructions if you want to build your own.

The P4 has the reset line functionality for auto-reset of BBB, Boarduino, breadboard Arduino (note copyright violation here) etc. Will also work fine on a Diecimila (or NG if you press the button)

pb

BongMaster,

Pay Attention!

The .sch I sent have two errors, that affect only .sch to .brd:

TTL Pin3 is not connected to +5v. TTL Pin4 is not connected to M8RXD

Redo NETs.

the layout i have right now works good.. all it needed was the reset line moved. its a good cable :) u have no idea hoe grateful i am for that schematic..

I hope to have a board made soon with the design i threw together this morning.

that schematic i a lifesaver :)

All I did was pick up a piece of circuitry from serial single sided (S3v3 Beta http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1196740449/45#45). In fact, you made half Serial Arduino! Nothing special on schematics.

well its helped loads :)