How to configure and use Garmin GPS 18 LVC?

[ericmar]

Hi guys,

May I know if anyone here can teach me how to use this GPS receiver (Garmin GPS 18 LVC, **broken link removed**) ? I'hv no idea how to configure it and use it properly. I tried one of the software that I got from its website (www.garmin.com) but I would like to use a simple serial communication application to send command to and receive data from this GPS receiver. I dont understand why I need to set the longitude and latitude in the Garmin software application since I was expecting to receive the location information from GPS.

Can anyone teach me?

Thanks!

Regads,
Eric

 

[C-Man]

datasheet del gps garmin

Hi ericmar,

I worked with Garmin GPS25 and GPS35 a few years ago.

All you have to do is enable the required output messages (using GPRMO) and you will get a new message every second.

You can initialize the unit if it has never been at your current position but this is not necessary. It might take longer to get the first valid fix under this condition but thats all.

Should you need any more info do not hesitate to ask ...

best regards

 

[ericmar]

nmea sentence gps-18

Hi ericmar,

I worked with Garmin GPS25 and GPS35 a few years ago.

All you have to do is enable the required output messages (using GPRMO) and you will get a new message every second.

You can initialize the unit if it has never been at your current position but this is not necessary. It might take longer to get the first valid fix under this condition but thats all.

Should you need any more info do not hesitate to ask ...

best regards

Hi C-Man,

Thanks for ur help again! Actually, I'm planning to interface this GPS receiver with my PIC18F452 and would like to do everyhing in USART serial communication. So I would like to know wat kind of message do I need to send to this GPS receiver after I connect it to my PIC? And wat kind of message I will get from the GPS? I'm expecting to connect this GPS receiver to my PIC and get the location and local time information from the GPS! I dont know why I need to configure the longitude and latitude in the Garmin application. I couldnt find any explaination for this configuration from www.garmin.com (what a bad support!).

I need to figure out this ASAP since I need to integrate GPS function into my device. So please do help me to get understand in using this GPS receiver!

Thanks.

Regards,
Eric

 

[C-Man]

datasheet gps 15 garmin

OK, first step I would do is connect your GPS to a PC and start hyperterminal 4800/n/8/1 no handshake.

Position your GPS receiver outside (connected to a voltage source) a few meters away from buildings and trees and after a very short while you should get your first position fix.

You must not do anything as the GPS sends position fixes every second.
Next you can enable the NMEA sentences you need (using the $PGRMO command) I would try $GPGGA or $GPRMC or even $GPGLL if you want to keep things simple check the manual which one you prefer or which one has all the info you need.

After you see the received sentences in hyperterminal the next step would be to connect the unit to your 18F452 and write your app ...

best regards

 

[Bingo600]

tia-232-f polarity

You dont need to send anything to the GPS

On the Garmin Select Output as NMEA protocol as opposed to Garmin protocol.

That will give you NMEA strings aend out the RS232 port , at : 4800,N,8,1.

Check with Hyperterminal or TeraTerm (better) , remember to make sure that neither hardware or software handshake is active in PC-Comport settings.

Then when you see the data , read up on NMEA sentences/protocol on the NET ....

/Bingo

 

[asic1984]

gps-18 rs232

hi

in epe magazine january 2004 ...........there is an article about interfacing with gps
i think it is the same type as yours or same company

 

[ericmar]

5v tia-232-f

Thanks everyone!

Wat if I want to trace something and keep moving the GPS receiver, will it still work?

 

[C-Man]

inverted gps longitude

Thanks everyone!

Wat if I want to trace something and keep moving the GPS receiver, will it still work?

Sure that is what GPS is designed for Garmins are specified up to 999 Km/H

May application was a data logger for gliders (sailplains) which also go up to 300 Km/H ...

best regards

 

[ericmar]

garmin 18 lvc pic

Thanks everyone!

Wat if I want to trace something and keep moving the GPS receiver, will it still work?

Sure that is what GPS is designed for Garmins are specified up to 999 Km/H

May application was a data logger for gliders (sailplains) which also go up to 300 Km/H ...

best regards

So how far I hv to move to see the longitude and latitude change? Wat about the altitude? I cant find any message which provides the information about altitude but when I use the Garmin software application, it shows Altitude!?

Thanks a lot!

 

[C-Man]

gps 18 lvc rs 232

Thanks everyone!

Wat if I want to trace something and keep moving the GPS receiver, will it still work?

Sure that is what GPS is designed for Garmins are specified up to 999 Km/H

May application was a data logger for gliders (sailplains) which also go up to 300 Km/H ...

best regards

So how far I hv to move to see the longitude and latitude change? Wat about the altitude? I cant find any message which provides the information about altitude but when I use the Garmin software application, it shows Altitude!?

Thanks a lot!

First you should know that GPS resolution for civil applications is around 10 to 15 meters in X and Y direction and about 20 meters in Z direction a few years ago things were worse as there was a so called "selective availabilty" of around 50 to 100 meters in x and y.

So when you move the antenna around for about 25 to 30 meters you will definitely see a change ...

The altitude can only be found in sentence $GPGGA field 10 and is called geoidal height.

In my project I used barographic altitude (derived from a pressure sensor) as primary altitude and GPS altitude as backup.

best regards

 

[ericmar]

gps18lvc

Hi,

Can anyone explains this to me? In PAge 8 of this GPS receiver's datasheet, it said :"The unit accepts TIA-232-F (RS-232) level inputs and transmit voltage levels from ground to the input voltage, TIA-232-F (RS-232_ polarity." So wat does it mean? Besides, how much voltage do I need to supply to it actually? I tried +5V and it works but it's not mentioned very clear in the datasheet!

Its datasheet: **broken link removed**

I'm trying to get the data from this GPS receiver through using a MAX232 however, I'm getting junk message! I tried invert the DATA but it doesnt seem to be correct either.

Thanks.

Regards,
Eric

 

[C-Man]

datasheet gps garmin

Hi,

Can anyone explains this to me? In PAge 8 of this GPS receiver's datasheet, it said :"The unit accepts TIA-232-F (RS-232) level inputs and transmit voltage levels from ground to the input voltage, TIA-232-F (RS-232_ polarity." So wat does it mean? Besides, how much voltage do I need to supply to it actually? I tried +5V and it works but it's not mentioned very clear in the datasheet!

Its datasheet: h**p://www.garmin.com/manuals/GPS18_TechnicalSpecification.pdf

I'm trying to get the data from this GPS receiver through using a MAX232 however, I'm getting junk message! I tried invert the DATA but it doesnt seem to be correct either.

Thanks.

Regards,
Eric

When you are using the LVC part you must use TTL levels (but inverted) the LVS parts use RS232 levels for example through a MAX 232.

As the datasheet says the unit accetps RS232 levels but only up to the supply voltage.

When you are using the unit with a +5V powered microcontroller you do not need a max 232 but you must use inverters in the receive and transmit path.

If you want to use this unit with a PC you must use MAX232 but you must also use inverters at the TTL side because the unit operates with inverted levels ...

The unit needs to be powered by +5V.
1.6.2.1
GPS 18 LVC 4.0 - 5.5V

best regards

 

[ericmar]

garmin 18 lvc bad

Hi,

Can anyone explains this to me? In PAge 8 of this GPS receiver's datasheet, it said :"The unit accepts TIA-232-F (RS-232) level inputs and transmit voltage levels from ground to the input voltage, TIA-232-F (RS-232_ polarity." So wat does it mean? Besides, how much voltage do I need to supply to it actually? I tried +5V and it works but it's not mentioned very clear in the datasheet!

Its datasheet: h**p://www.garmin.com/manuals/GPS18_TechnicalSpecification.pdf

I'm trying to get the data from this GPS receiver through using a MAX232 however, I'm getting junk message! I tried invert the DATA but it doesnt seem to be correct either.

Thanks.

Regards,
Eric

When you are using the LVC part you must use TTL levels (but inverted) the LVS parts use RS232 levels for example through a MAX 232.

As the datasheet says the unit accetps RS232 levels but only up to the supply voltage.

When you are using the unit with a +5V powered microcontroller you do not need a max 232 but you must use inverters in the receive and transmit path.

If you want to use this unit with a PC you must use MAX232 but you must also use inverters at the TTL side because the unit operates with inverted levels ...

The unit needs to be powered by +5V.
1.6.2.1
GPS 18 LVC 4.0 - 5.5V

best regards

I tried connecting this unit directly to the PC via serial COM port without using MAX232 and it works. I only supply +5V to it and i didnt do any inversion. How come?

On the other hand, I tried passing the information to the PIC by connecting the TX line (from GPS receiver) to RX line (of PIC) and then echo back the data to the PC by connecting the TX line (of PIC) to the RX line (of PC serial COM Port ) through MAX232. It didnt work! I tried using a Hex inverter IC to invert the data in between of the PIC and MAX232, it still didnt work! I can get some junk messages and they appear to be repeating pattern which I suspect i could hv made a minor mistake!

Thanks for help anyway!

Regards,
Eric

 

[C-Man]

garmin+36+gps+pdf

I tried connecting this unit directly to the PC via serial COM port without using MAX232 and it works. I only supply +5V to it and i didnt do any inversion. How come?

Thats clear because the output of your GPS unit is already inverted and as most PC's accept TTL level (must be inverted) as input thats why it works

On the other hand, I tried passing the information to the PIC by connecting the TX line (from GPS receiver) to RX line (of PIC) and then echo back the data to the PC by connecting the TX line (of PIC) to the RX line (of PC serial COM Port ) through MAX232. It didnt work! I tried using a Hex inverter IC to invert the data in between of the PIC and MAX232, it still didnt work! I can get some junk messages and they appear to be repeating pattern which I suspect i could hv made a minor mistake!

Thanks for help anyway!

Regards,
Eric

You must use an inverter between the TX from the GPS receiver and the RX of your PIC.

When you want to echo data back to your PC you can either connect TX of your GPS module direct to RX of your PC or if you want to connect the signal from the TX pin of your PIC you must again use an inverter from your PIC's TX pin to the RX pin of your PC ...

best regards

 

[sara63]

garmin gps wont output without rx connected

Hi,
I have a gps(GM-R500).I want to connect it to AVR microcontroller.It has a ps/2(femail) port that has 6 pins:
1:VCC
2:GND
3:RX (RS232 level)
4:RXD (TTL level)
5:TXD(TTL level)
6:TX(RS232 level)
I use the pins with number 4 (RXD) and 5 (TXD) for connecting Gps to AVR.
I programed AVR to show "NMEA" sentences in LCD.but the data taht i see in LCD isn't correct.
I set the Buad Rate in AVR to 4800.
Should i use invertor between AVR and Gps?
What clock frequency should i set in AVR?
Is there anybody help me?:?:

 

[sara63]

bascom nmea sentence

Isn't there anybody help me?

 

[GDetienne]

garmin gps 18lvc datasheet

All is write just before your post....
Search with google what are the differents RS232 norme. You find :
"RS232 F" : it's electric level 0 - 5V and inverted signal.
"RS232 C" : electric level -12 and +12V with inverted signal.

Then for RS232 C you use level translator + inverted = Max232
For RS232 F only inverted (harware or software). It's the norme used by Garmin.

For NMEA sentence, first you download the description of each sentence (available on the NMEA web site). Then you can understand what you receive.

Be carrefull, the Garmin GPS send also another format of sentence. To be sure to receive the good one, connect the GPS directly to your PC and start the config prog of Garmin to control it (SNSRCFG.exe).

Good luck.

 

[sara63]

tia 232 f

Hi,
Thanks for replying.
I connected the GPS to computer and saw its output in Hyperterminal and it was correct
When i worked with Bascon(the software of AVR MCU) i didn't answer but when i changed my software to Codevision i answer.
I think that my problem was becuase of Bascom.