BS2 and GPS

Mike15

I have seen alot done with the BS2p and GPS but can the BS2 be used.

Is it possable to get the sentence strings to display in the debug termanal?

Bruce Bates

Mike -

It's doable, but you'd have to do it a piece at a time, which means you'd be displaying segments of (timewise) different sentences, albiet the same sentence type, since in most cases the entire GPS sentence string will not fit into the 26 bytes of BS-2 RAM.

Unless you just need a minimum of information the BS-2 is not the "right" Stamp platform for use with a GPS receiver, IMHO. Just going to the BS-2e will give you the added string space necessary, or migrating to the BS-2SX will give you both more speed and string space necessary to do a really decent job.

There were some earlier musings about a GPS pre-processor chip, but I'm not sure what's to really be gained in speed or price with such a configuration, over using the BS2e or BS-2SX. Admittedly, I know little about the tentitively planned chip, or what advantage it's supposed to offer. FWIW, I suppose it might bring both the BS-1/BS-2 into the GPS processing market, which does sell more low end microcontrollers.

My own POV has always been to pick the processor with the right features BEFORE I start the project, and I'll then not be sorry somewhere down the line before the project is completed. Just my own 2 cents, and worth just about that

Regards,

Bruce Bates

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Jon Williams

It's tough to use the BS2 with standard GPS strings; if you have a Garmin GPS that allows Garmin text output (like the eTrex), you can use the attached program.

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Jon Williams
Applications Engineer, Parallax

roberto_ita

hi,

i try to use this code with BS2 board but it doesn't work!

i done these step:

- garmin etrex - ASCII @ 2400 baud, data out --> P15 , ground --> VSS
- on the program code i modify: Rx PIN 15

i see on the bottom of my BS2 that is a BS2p-IC, but if i try to identify the program identify it as basic stamp 2 v1.0

tanks in advice

PJAllen

You need to change the Stamp Directive to match the device/Stamp that you are using.· You have indicated that you have a BS2p.

Near the·top of·the program that Jon uploaded, there is a line: '·{$STAMP BS2}

which you need·to change to -- '·{$STAMP BS2p}

I have made the change in the attached program.

roberto_ita

I done it, but the basic stamp editor tell me that here is no PS2p connectend. I discovered that is an early version of the BS2, then the program is correct but it doesnt work! :-(

PJAllen

The connection between the eTrex Data Out and the Stamp's P15 should be through a 22KΩ resistor.

Data Out --> 22KΩ_--> P15

roberto_ita

ok, i will try!

roberto_ita

nothing.. i use a 22kohm (red, red, orange) between data out and P15 but nothing.

the gps work well because if i use a serial sniffer i see the garmin ASCII data output..

i checked the cable connection with tester and all is ok, the stamp is ok, what's wrong?!!? :-(

PJAllen

I don't know which connector Garmin uses on its device.· Is it M, is it F?· I have no idea, people just do what they want to do.· Hopefully, pin 5 is Ground.· Do you know, by use of your·tester, which pin (2 or 3) the data is on?· If pin 2 doesn't "work", roll your data and try pin 3.



Post Edit -- I suppose you should be able to read data, using Hyperterminal, because it is supposed to be text data out.

Post Edited (PJ Allen) : 6/15/2008 3:05:30 PM GMT

roberto_ita

the wire connection is ok,

i have a garmin data cable cutted and connected to my demo board. ground to VSS and data out to 22k ohm then to the input pin..

but on debug i always have "No Gps".. :-(

PJAllen

I'd try and verify data using Hyperterminal.

(Actually, I would use STGold, but Hyperterminal is a Windows common-place.)

Maybe you can take a picture of your situation?

roberto_ita

this is my circuit, i change the input pin to PIN 0.

PIN0 -> 22k ohm -> garmin data out (brown)
VSS -> garmin ground (black)

PJAllen

You're certain that what that's showing is what's here:

roberto_ita

yes, sure!

i found this and i use it for the connection, black wire ground, brown data out.

maybe baud problems??

PJAllen

roberto_ita

yes, is a perspective probelem.. the cable that u mark on red go to P0.

my basic stamp is an old revision (revision E) it's helpful?

maybe there is some problem with baud?!? i'm going crazy!

allanlane5

Looks like you're trying to use the "Programming Port" (16). That port has built-in level shifters -- so there, you don't need the 22 KOhm resistor.

roberto_ita

ok, i will try to use the P16 (SERIN) without resistor..

but is possibile to know the difference between my board "revision E" and the actual "revision J"? It was bought in the 1998..

roberto_ita

this is amazing..

now it work because... i attacched the other side of garmin data cable to another pc with rs-232


PC <

---

> B2s <

---

> Etrex

if i disconnect the rs232 from the second pc bs2 dont read nmea sentences...

any idea?!?!?