Author Topic: will this work (now with pics) (Read 3531 times)

ed1380 · « **on:** November 23, 2007, 06:39:17 PM »

so I'm building this http://www.popsci.com/popsci/how20/ddb6bb1fd9ca4110vgnvcm1000004eecbccdrcrd.html

it calls for usb for power. got that.

but needs serial (db9) and ttl->rs232 for data.

so instead of doing GPS->rs232 converter->DB9->usb converter->PC

I want to do GPS->USB->PC

will this work http://www.acroname.com/robotics/parts/S22-USB-SERIAL-INT-CONN.html
or this http://pdncons.com/mm5/merchant.mvc?Screen=PROD&Store_Code=PDNCONS&Product_Code=A-USBToTTL&Category_Code=SERIAL

thanks guys

EDIT- will it work with vista

frank26080115 · « **Reply #1 on:** November 23, 2007, 07:42:02 PM »

http://www.sparkfun.com/commerce/product_info.php?products_id=718 <-- cheaper

and yes it will work

ed1380 · « **Reply #2 on:** November 23, 2007, 08:07:12 PM »

thanks.

and even better cause i already have a usb A to usb A cable

only piece of concern I have is- it's set for 3.3v and the gps module needs ~5v. do I just take an extra set of wires from the plug and send it to the module?

will I need to solder the jumper?

usb can handle 500mA right? google sucks

Admin · « **Reply #3 on:** November 23, 2007, 08:14:56 PM »

Quote

only piece of concern I have is- it's set for 3.3v and the gps module needs ~5v. do I just take an extra set of wires from the plug and send it to the module?

just take the 5V from the USB line and ignore the 3.3V pin.

Quote

usb can handle 500mA right? google sucks

the first hit on my google search got this:
http://www.usbpluspower.org/
yeap, 500mA
(I don't think it was google that was sucking

)
j/k!

ed1380 · « **Reply #4 on:** November 23, 2007, 08:58:58 PM »

what else do I need to consider? what am I overlooking?

thanks admin. I searched for like 5 minutes in google and couldn't find anything

ed1380 · « **Reply #5 on:** November 23, 2007, 11:36:17 PM »

ok. some more questions/complications

1- it says if I unsolder the jumper I can do 5v IO. to where do i connect the output if i want 5v IO? just the 5v line from the usb cable

2- the author of the article did GPS->rs232 converter->DB9->usb converter->PC. Why? is it necesary for it to work?

3- Will attached pic work?

Admin · « **Reply #6 on:** November 24, 2007, 08:55:09 AM »

Quote

1- it says if I unsolder the jumper I can do 5v IO. to where do i connect the output if i want 5v IO? just the 5v line from the usb cable

just ignore that 3.3V line entirely. Solder a wire to the 5V on the USB to connect to your other electronics, and do not solder it to the 3.3V line.

Quote

the author of the article did GPS->rs232 converter->DB9->usb converter->PC. Why? is it necesary for it to work?

each of those devices use a different signal, and so the converters change the signal. using this TTL to usb converter you bipass the rs232 signal. rs232 is the old way of doing things, so people still occasionally do it.

Quote

Will attached pic work?

don't connect anything to the 3.3V line, and then it will work

ed1380 · « **Reply #7 on:** November 24, 2007, 10:11:58 AM »

ok. so like this? (atached pic)

there is RXD1, RXD2, TXD1 on the GPS module. RX, TX on the converter. what gets connected to what? cause what I drew is diferent from what the author did.

Admin · « **Reply #8 on:** November 24, 2007, 10:53:16 AM »

yea, the power is correct.

you'd have to look up/read the gps datasheet to be sure where everything goes . . .

without looking up your gps datasheet, i think you got the tx/rx connections wrong.

you want the output tx on the gps to connect to the input rx of your usb board . . .

ed1380 · « **Reply #9 on:** November 24, 2007, 11:40:58 AM »

the left half of the pic is from the datasheet.

so RX gets connected to TX and vice versa.

Thanks

I guess I'm off to order the stuff

frank26080115 · « **Reply #10 on:** November 24, 2007, 12:15:59 PM »

On the USB to serial module, the pin labeled VCC is 5V, top right of the image

ed1380 · « **Reply #11 on:** November 24, 2007, 06:33:39 PM »

o yeah. I'm so stupid.

should I get a plastic or aluminum project box from Radioshack. will the aluminum be effective at all with helping eliminate RF inteference?

paulstreats · « **Reply #12 on:** November 25, 2007, 08:28:47 PM »

i would personally go for a plastic box, since its likely to be more durable and you dont have to worry so much with shorting your board if it touches any metal.
I dont think aluminium would stop interference that much, you would want something more conductive such as copper.
if you use the plastic box, maybe you could make a copper wire grid around the inside maybe 0.5 cm apart like this

| | | |
-------------------------------------
| | | |
--------------------------------------
| | | |

connect the grid to ground and it should stop interference.

it would stop waves getting through just like the holes in your microwave door are just small enough not to let the microwaves pass through. because you want to stop larger waves you can have a larger spaced grid.