GPS to SMS controller

L

lanternfish

Senior Member
Stupid mistake has just killed my GPS to SMS rocket locater and all the smoketrons escaped!

While preparing the enclosure for this project I accidently placed the GPS board & PICAXE pcb onto the (yet to be insatlled) groundplane for the active antenna. At some point I must have operated the supply switch because ...

Called away by my wife at that very moment, I returned about 15 minutes later to the faint aroma of electronics bbq'ing.

And nothing works, except the cellphone.

At least it all (finally) worked, after a bit of code tweaking.

Oh well, try and locate another GPS board locally, and rebuild.

For those who were interested in SMS via AT commands, will post code and info soon(ish).

cheers.
 
B

BeanieBots

Moderator
How annoying:mad:
Nothing worse than a dissaster when you are so close and even worse when you know it was your own fault. It helps when you can blame someone else.
That's a core responsibilty of wives. Try it. It helps. She'll understand.
 
B

BeanieBots

Moderator
That sounds like faulty programming or selection of the wrong model.
Maybe you have confused the violent reaction as an error. That is in fact normal behaviour and is to be expected.

Don't forget, it's bi-directional effect.
How often do you get blamed for washing-machine/boiler or similar malfunctions?
Have you ever noticed how car ownership transfers as a function of tank contents or with proximity to MOT/service requirements?
 
M

MPep

Senior Member
Oh LF, what a bummer.
Hope you get it all up and running soon (again :)).
Look forward to reading your code for SMS generation.
Can't remember, are you using PDU or text?

Tongue-in-cheek there BB. Although must say that I hadn't realised the similarities between wives and electronics. Surprisingly accurate definitions there. :D
 
L

lanternfish

Senior Member
Good news. The PICAXE survived as far as I can tell. Seems the 5V and 3V regs took the brunt of it. Not sure if GPS board is ok yet. Fingers crossed!

@MPep

Using text. AT commands work well but had to do lots of loops to get timing/error reporting sorted out.
 
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M

MPep

Senior Member
Yeah, text makes life infinitely easier. :D
PDU is darn difficult to encode into. But this is universally accepted (by pretty much all GSM type modems). Not many modems use text.:(
 
M

MPep

Senior Member
LF, you mention timing loops etc to get timing correct? Why? Does your GSM module not acknowledge receipt of a command, eg OK being received by the PICAXE?

I initially had a similar issue with an Iridium modem I was working with. Took a while for the penny to drop, but after it did, simply waited for OK then proceeded with the next command.

As NickWest asks, what GSM modem are you using?
 
N

nbw

Senior Member
Hurrah for regulators! And shame on the wife for distracting you. You have kids? If so, perhaps they could distract her from distracting you... :) ALso reminds me of that old saying: a $600 TV tube will protect a 10c fuse by blowing first.........
 
L

lanternfish

Senior Member
LOL. The kids are all grown up and enjoying their freedom from the 'olds'. And Coronation Street doesn't seem to do the trick anymore!

The GPS is definitely dead. Have just picked up a 3V GPS so I will be buying a 3V 28X2 and can drop the voltage/level converters to the cell phone on the final PCB. Of course, soldering a 28pin SOIC is going to be an experience. Have managed to get pretty good results with R's, C's and the odd SOT23 packages.

Have had time to review my code and have found a couple of sections that can be trimmed. Not that the app is time critical in terms of processing.

Have started to write up my experience with all this and will post mid to late next month. I will also put it up on my website (up but still to be completed) around the same time.

Cheers
 
N

nbw

Senior Member
I've heard of folks having a lot of success with SMD and solder paste/flux combo. I'm also of the type where it all looks a bit delicate for my aging eyes and hands haha
 
L

lanternfish

Senior Member
nickwest said:
Shame about the expensive smoke... What GSM module are you using?
Click to expand...
I am using an old Nokia 6100. Cost nothing :) and plenty of info on interweb about interfacing to Nokias.

MPep said:
LF, you mention timing loops etc to get timing correct? Why? Does your GSM module not acknowledge receipt of a command, eg OK being received by the PICAXE?

I initially had a similar issue with an Iridium modem I was working with. Took a while for the penny to drop, but after it did, simply waited for OK then proceeded with the next command.
Click to expand...
And the penny dropped for me, too!:eek:

I was writing the GPS data to the phone and saving the message using the AT+CMGW command before transmitting SMS using the AT+CMSS command.

The AT+CMGW (Write Message to Memory) command stores a message in memory. The memory location is returned in the acknowledgement +CMGW:index, where index is the memory location. This can be one or more digits.

I was then sending the AT+CMSS=index (Send message from Storage) command, having extracted the index from the reply. This worked well as I wanted to store the GPS data message as a backup should something go wrong with the transmission of the SMS message.

As it turned out, the timing issues I had were to do with a dodgy (and unnecessary) gosub routine that seemed to upset the gosub stack causing the return to a previous on variable gosub routine.:eek: And my trying to also capture any +CMS ERROR message, should it occur.

Clearly I didn't need to capture the error message as the timeout feature of the serin command can fulfill this function e.g.

Code: 
     SERIN  [10,CMS_Error], CELLRX, T4800_8
This has allowed me to remove a muxing chip and dedicate the hserin/out pins to the GPS unit as I was using the scratchpad as a temporary store for the NMEA data, which was parsed and the necessary data extracted. this worked very well once I dealt with the Schmitt Trigger aspect of the hserin pin.

It will be simpler to send the message without saving it to memory first. And it will certainly save a bit of code. But as I am only expecting to send 3 messages per rocket flight (pre-launch location & altitude, ejection/apogee location and altitude, landing location location and altitude), I will be able to clear the phones memory before the next flight.

All in all, I have found this project challenging but very satisfying. Apart, of course, from the recent 'fry up'.:mad:

And the new GPS module is far smaller than the Rockwell Jupiter module. And as it is 3V I will be using an SMD 28X2 on the final interface board everything will be more compact and lighter. See post #13.

And of course, this forum and the excellent advice from the many contributors has contributed greatly to this project.

Cheers
 
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