Tuesday, 13 January 2015

how do you solve a problem like a green dot?

Belfryboy Clone green dot logger When the "green dot" problem arose I was at a loss as to how to fix it. But that half the fun.  Then we found the solution. Several in fact. Torkelmj uses a novel method, by programming an Atmel ATtiny microprocessor to behave like a Dataflash chip with the correct security register the Davis console will open its communications port.

But this was not satisfying for me. I wanted to still use the logging abilities. WXforum member Travisc came up with another solution using a PIC to fool the console that then turned itself off and enabled the logging chip once the console was happy.
traviscs solution, very elegant
This was all very well, but still not what I had in mind, but with some collaboration the solution arose. The algorithm used was cracked by comparing genuine logger security registers and the Belfryboy logger was reborn.

All I needed was a way the program the chip.

I initially I started to program the chips using a buspirate in SPI mode and an SO8  ZIF socket. The security register was calculated in Excel and then flashed into the chip. This worked most of the time, but not always.

I tried in vain to write the code to use an arduino board to program the chips, JoeBean beat me to it!

It was then just a case of putting his code on to my fixture and voila, I had a fairly foolproof method of quickly programming the chips.
The finished programming fixture.

Green dot logger page now live

The Stand alone page for the Belfryboy Clone "green dot" logger is now up and running, just hit the tab at the top of the page!

A page for the SHT15 based clone temperature humidity sensor is on it's way too.

Monday, 12 January 2015

then the famine, and finally eureka!

I decided to make the clone loggers work with WeatherLink in mid February 2012. This went well for the best part of a year and a half with steady sales. And then something bad happened. I started to get emails from users stating that their console would return the message "incompatible logger".

This was a problem. Davis had updated the firmware on their latest consoles to only accept genuine Davis loggers. I didn't have a clue what they had done. But it did turn into a nightmare for them as well; their older loggers also didn't work.

This became known as the green dot issue since all the latest consoles were supplied with a green sticker on the packaging.

This is when the famine started, I could no longer supply my clones.

But then came the Eureka moment.

WXforum member rdsman made the suggestion that Davis were programming the security register in the logging chip. After several months of chasing around we had found the actual method used. All credit for this must go to members rdsman, torkelmj, travisc, and more importantly watson, who published the algorithm.

This led to me being able to sell loggers again.

Sunday, 11 January 2015

and then came the flood....

The flood really started as a trickle. In February 2012 I respun my boards so that I could use a serial or USB interface and offered it for sale on the WXforum. I got plenty of interest, selling 20 of them in a relatively short period. Here is a finished board awaiting its cable.
and with its cable fitted and installed in a Davis Vantage Pro 1.
It became apparent that to successfully use the logging facility on the interface you needed to send it some simple commands using a terminal emulator. I found this could be unwieldy so spoke to a software developer and got a set up  utility created. At this stage the loggers didn't work with the Davis WeatherLink software. This soon changed though...

In the beginning there was lightning!

In 2007 I installed a weather station at the Wessex Cave Club headquarters in the Somerset village of Priddy on the top of the Mendip hills. This station was intended to log data to assist cavers with projects and to give them an idea of current weather conditions.

But alas, a passing thunderstorm zapped the unit causing the interface between the console and the greatness that is the internet. The equipment was removed and continued to gather dust until 2011 when I decided to fix the kit.

I initially searched for second hand equipment but the cost was prohibitive, but fortuitously stumbled across the WXforum and this post from DeKay, it spawned the first logger. Here is the first attempt created using Eagle PCB.

and then built using a free service from Spirit Circuits

 This first unit used an FTDI serial to USB cable. I offered it for sale and put the design files up so that any hobbyist could build one. It would appear that people preferred to have me build them one...

And so it begins....

So I had to begin somewhere. This blog is a means of tracking the developments of the now world famous Belfryboy Clone Logger.

Back in 2011 I had a clear out and found a bunch of Davis Instruments weather kit that had been taken down after suffering a lightning strike. The datalogger was dead and I needed to get the station up and running again.

After a little searching I came across the fantastic WXforum and found a superhero/kindred spirit/mentor/inspiration in the form of forum member DeKay. His fantastic blog is full of all the information that I needed to get me on my feet again.

Well that was over 3 years ago and the logger that was spawned then has become a cottage industry for me. In the next series of posts I will detail the development of this affair.