Go Down

Topic: External arduino still with Serial connection capability? (Read 1 time) previous topic - next topic


hello and thank you for viewing. I have been creating some code for some lights and using others to try and combine multiple functionality within it. At the moment I followed a video to control the RGB spectrum (10 bit of course) with your iPod using a simple app and I would like to do some other things like add sequences through pushes of buttons.

As I hope for this project to be a little cheap I would like to buy one of the atmel chips and put it into a circuit board (well strip-board) and make it run by it self. One problem I looked at is that the chip actually interfaces with serial so I need some help with finding a relevant serial connection to hook up to the arduino. Could any one help me with this? Is there a really simple chip that does this? On my desktop it is a high performance therefore only really having USB and no parallel or Serial connections. So pretty much I am looking for some schematics. I also would like to know if any one sells any pre programmed chips so that I dont have to buy a programmer.

There must be some one out there with the same problem  Thank you all and see you soon :)



I think it's possible you're confusing the concept of serial (as in "communication", http://en.wikipedia.org/wiki/Serial_communication) with serial (as in RS232 serial on older PCs).  USB data communication is serial.

Depending on the Atmel chip you're looking at, there are many ways to get them to talk to other devices serially.  I'll presume you're talking ATmega like in the Arduino, so you'll have SPI and the serial UART on pins 0&1 as well as the ability to implement serial comms on most of the other pins via the SoftwareSerial library.  So you'll have many methods of communicating short distances via serial (ie bit-at-a-time) comms. 

However in the text here you've mentioned communication with a PC and the Arduino.  Do you need a standalone chip that will be talking to both?  And over what distances?

Cheers ! Geoff
"There is no problem so bad you can't make it worse" - retired astronaut Chris Hadfield


Thank you for your reply,
I have a processing app on my computer that 'talks' to the network and with touch osc. This is just to control some lights so it will be only the length of my usb cable of about 2 meters. How would I go about hooking the usb to the arduino? I guess ill have to use some sort of serial converter IC? Would you be able to suggest one? Thank you ever so much :)


I guess ill have to use some sort of serial converter IC? Would you be able to suggest one?

Have you looked at the Uno schematic? Most Arduinos come with a USB to serial converter.
The art of getting good answers lies in asking good questions.


Thank you again for the reply, all I figured that i was able to recieve some information about the schematic, the arduino uses an  FT232RL? I have the schematic here:
http://www.arduino.cc/en/uploads/Main/Arduino-Diecimila-schematic.pdf I could just copy this schematic on a strip board and it should work? One little question though, on the FT232RL the pins 6,10,9,11 they connect to 1,2,3,4 on the schematic file? I dont really understand where they connect?


Basically, you just want to do the whole Arduino-on-a-breadboard thing, and communicate via serial with the chip?  Yeah, that's dead easy.  You just need an FTDI cable.  Most of the tutorials cover such a thing.

Parts list:
- ATmega328P-PU
- 16MHz crystal or ceramic resonator
- If the above does not have three pins (built in caps), you also need 2x22pF ceramic caps
- 47 to 100uF electrolytic cap for power filtering
- A few 0.1uF ceramic caps (one on each side of the chip, between Vcc/AVcc/Aref and Gnd to filter noise, and one between serial DTR and the reset pin)
- A 10K resistor from reset to Vcc
- A 1x6 male 0.1" pin header for connecting to the FTDI cable
- Breadboard, jumper wires, etc.

Then, add anything your project requires... LEDs, resistors, buttons, etc.


Very interesting, and thank you. I shall have to try this on the weekend. One thought... could I use an old picaxe programming cable to do the whole usb to serial thing? It just outputs serial. Could I use this?

Nick Gammon

Maybe, but the PICAXE cable doesn't have the RTS pin which means you would have to manually reset the board being programmed at the right moment. It also doesn't supply power so you would have to power it separately.

I'm not sure if the driver would be compatible - it might be.
Please post technical questions on the forum, not by personal message. Thanks!

More info:

Go Up

Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

via Egeo 16
Torino, 10131