Jump to content
sonnyace

how gps EM-411 connected to max232?

Recommended Posts

does anyone knows how to connect a em-411 gps module to a computers COM port through max232 ic? i found this schematic that i think shows how its done. but should RX and TX on the gps switch places?

and how will i receive data/code/ascii or what ever i will get and turn them into coordinates? any programs or source codes that anyone knows about?

my english sucks so if its not clear of what i need help with please reply and i will explain futher. i really need help with this.... its a school project =)

(i do not guarantee that the schematic is correct or even understandable)

post-6-1194996750_thumb.jpg

Share this post


Link to post
Share on other sites
but should RX and TX on the gps switch places?

You are correct, the GPS's RxD and TxD are backwards on the schematic.

Be careful with the EM-411 data sheet since tGlobalsat published early copies with the wrong pinout. The data sheet found on the dpcav.com web site is correct.

and how will i receive data/code/ascii or what ever i will get and turn them into coordinates? any programs or source codes that anyone knows about?

The NMEA sentences are ASCII text. You can see them with any terminal program (Window's Hyperterm works fine).

Share this post


Link to post
Share on other sites

Also, if you want to save yourself a little time and the application while doing bench work you might want to pick up one or two of these.

http://www.sparkfun.com/commerce/product_i...products_id=133

or

http://www.acroname.com/robotics/parts/S13...L-INT-CONN.html

You will of course probably want the level conversion integrated on board with your final version of the project, but these little guys are super handy when doing prototyping etc.

Share this post


Link to post
Share on other sites

thanks guys!

but what are the two other RX and TX outputs for? the COM port uses them all but not the gps, how come?. the origional schematic says "CTS" and "RTS". could it might be "clock" and "reset"? do i even need those output/inputs?

one final question. do both the gps and 232 use 5volt?

Share this post


Link to post
Share on other sites
but what are the two other RX and TX outputs for? the COM port uses them all but not the gps, how come?.

Those are unused RS-232 signals. They are not needed.

do both the gps and 232 use 5volt?

Yes. Please observe their data sheets.

Share this post


Link to post
Share on other sites
thanks guys!

but what are the two other RX and TX outputs for? the COM port uses them all but not the gps, how come?. the origional schematic says "CTS" and "RTS". could it might be "clock" and "reset"? do i even need those output/inputs?

one final question. do both the gps and 232 use 5volt?

CTS and RTS are only used when flow control is active.

Clear To Send

Request To Send

as noted, the GPS units do not use them.

Share this post


Link to post
Share on other sites

serial ports on computers are a slowly dieing race :-)

so maybe you should consider USB ?

http://www.intelligentflight.com/store/ind...7cde06aa06db35c

http://www.webx.dk/rc/video-wireless/usb-05-317

simply install the FTDI driver and you have a virtual (usb) comport,

and all your PC programs that are normally used to talk with GPS units

will also work, this USB interface have a free place to add a zero ohm 0603 size resistor,

so you will get USB power +5V out to your GPS unit, neat, no need for powersupply it is all runned from USB.

Edited by ThomasScherrer

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×