voelker

The box was opened on the 2nd of january ! My cousin completed the seven steps in tow days. It seems that the information the box gave (distance + bearing) made it a bit too easy ... Everything worked really fine (no bug or unexpected behavior), and my cousin can now store anything in it and keep it safe for year. I was a bit anxious that something could go wrong (its hard to test everything ...), but i'am really happy with the result. The box cost me around 40

I gave the box on the 24th and explained how everything works to the new owner. On the 25th we took the box for a ride and completed the first step using the distance and bearing information (bearing is a bit hard to understand as i have no magnetometer in the box). It worked very well (the 100m tolerance is a bit too large to reach precise waypoints), and the owner seemed very happy with it. It was for sure the best present i ever gave, as it required more than a credit card (late night working).

i did teh final testing today and ... it didn't work! In fact i did all the testing in my hometown of Toulouse (east from the greenwwich meridian) and i did today's testing on the west of the greenwich meridian ... It means that the longitude information became negative, and an unfortunate use of unsigned integers led to a bug. Everything is now fixed and should hopefully work without a hitch on the big day.

When i developped the code i tried to use the libc function from math.h but cos, sin, sqrt would take too much space (i still don't really understand why ..). Only the atan2 function would work fine, but i decided to use a fast implementation found on internet. More over using my own function allows me to play with precision (i 'm only doing the relative positionning with a 100m precision). Even if my function are not optimized i have no problem, as i compute the distance and bearing only at 1hz.I also have implemented my own configurable parser for the gps stream, and my own sprintf routine

@Fred : Nice project, how did you do to point the arrow to the right directions without a magnetometer ? I like the idea of having different challenge to solve. I thought of hading chalenges (timed circuit, riddles ...) but i needed to be ready for christmas ...

Hi, the targets are hard-coded ... By loading i mean that when a target is reached, the code switch to the next programmed target. When i was thinking of what to design i decided to buy the minimum parts. I only bought the display (5

Here is my entry to the project of the month contest, my geocache box. This box is an MSP430 based implementation of the reverse geocache puzzle. I will give this box to one of my cousin for christmas. To get the box to open, he will have to go through seven different locations using distance and bearing information. When all the destination will be completed the box can either be used as a development kit (gps+servo+display+switch), or serve as a personnal safe that remain closed for one year. All the code can be downloaded from http://code.google.com/p/msp430-reverse-geocache/. Video and s

Hi, i'am proud to present my latest creation, the launchpad based geocache box. Some of you may have read the story of the original reverse geocache puzzle (http://arduiniana.org/projects/the-reve ... he-puzzle/). I was looking for a gift to build for this christmas and i decied to build my own geocache box. I first thought of using an ARM micro-controller but the launchpad with an msp430g2553 seemed like a perfect fit. I dug into my electronic junk box and found a bluetooth gps module and a servo. I ordered a lcd display (3v compatible) and a switch and i was good to go ! The box is a w

i found my problem, and the problem is ... me ! I used haversine function on angle in degree decimal-minute while it should take angle in decimal degree ... Everything is working fine and my implementation gives an error of ~10m compared to an implementation using math.h with double type.

Hi, i have more cpu cycles and rom space than i need, so i'am looking for something that fits the value line ram.

my code sometimes does not catch an interrupt causing the TX buffer to never be filled by the interrupt handler. I'll try to solder a 3.3v regulator and see how it goes. Thanks for your help, i'll post my code soon.

Thanks for the link, i'am gonna check it. i'am using these functions to cimpute distance between too set of gps coordinates. The distance computation is fine for long distance but for short distance, the function underestimate the distance. For example for a 8.6km distance i get 5.6km. The point is that for a short distance like 600m i get 480m ... it seems that the error is not linear or happens for some specific values. This precision is sufficient for my application but i'd like to understand the problem.

my usci code becomes unstable when running the device for some time ... but i may have the explanation ! I'am running the msp430g2552 at 16mhz with a 3.0v power supply. The datasheet states that a device running at 16mhz should be powered by 3.3v to 3.6v. Do you think that powering the device at 3.0V can cause some weird behavior when running at 16mhz ?

Hi all, for one of my project i need to use sin, cos, sqrt, atan2 functions from the math library. When i'am using atan2 function, everything goes fine, but when i try to use sin, cos or sqrt, the compiler says it cannot allocate the bss segement (ram). Does any of you know an alternative to the math library with a small footprint ? I have implemented sin, cos and sqrt my way, but cos and sin seems to suffer from precision problems (taylors series). Thanks

Everything is working fine now, my custom sprintf routines work well for the display, i parse gps stream, and i can store data to the flash ... seems that i'am ready to submit my project to this month contest. Still need to shoot a video, and draw the schematics. Thanks for everybody's help.