Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: pomprocker on April 12, 2008, 01:33:21 AM

Title: $50 robot TTL to USB breakout
Post by: pomprocker on April 12, 2008, 01:33:21 AM

I bought that breakout from spark fun as shown in this picture:

(http://www.societyofrobots.com/images/microcontroller_uart_USB_adaptor2.jpg)

Does anyone know how to cable it up?

The one pin says 3.3v but the one that does not have a header on it near the top where it says 2103 is 5v

I mean i think I got it, but I don't want to fry anything.

Title: Re: $50 robot TTL to USB breakout
Post by: michaelsane on April 12, 2008, 02:58:44 AM

I am relatively certain that the 3.3v is for you to sink current from,  so unless you need a 3.3v supply it shouldn't be necessary.  Where you connect it to your mcu just depends on whether you are using  a hardware UART or software.  Just consult the data sheet for information about the hardware UART ports.  You will need to be sure to connect the ground from the USB module to the ground on the mcu. 

Title: Re: $50 robot TTL to USB breakout
Post by: Admin on April 14, 2008, 07:21:26 PM

It takes power from your PC, so all you need to connect is rx, tx, and ground.

In that pic I was using the 3.3V to power my external wireless transmitter.

Title: Re: $50 robot TTL to USB breakout
Post by: pomprocker on April 14, 2008, 07:38:40 PM

ohhhhh, I actually made a crazy cable that sends 5v from the power on the sensor bus to the 5v pin on the breakout board. ill attach a pic later.

EDIT: So thats 5V out not 5V in? and same with the 3.3V pin?

Title: Re: $50 robot TTL to USB breakout
Post by: pomprocker on April 15, 2008, 10:10:02 AM

Thats what was causing all my problems with the bootloader not working properly  :P

Title: Re: $50 robot TTL to USB breakout
Post by: Admin on April 15, 2008, 11:43:09 AM

Quote

So thats 5V out not 5V in? and same with the 3.3V pin?

Well, by default they are both outputs. However, if USB power isn't connected, you can connect your own power to it.

You can also reconfigure it in software to be inputs or outputs:
http://www.silabs.com/tgwWebApp/public/web_content/products/Microcontrollers/Interface/en/interface_documentation.htm
http://www.silabs.com/public/documents/tpub_doc/anote/Microcontrollers/Interface/en/an144.pdf
http://www.silabs.com/public/documents/software_doc/othersoftware/Microcontrollers/Interface/en/an144sw.zip