jappelino

I have tried some different version for the power source. At present it is 3 AAAA batteries connected to a LM58117 to provide power to the CPU and the Zigbee unit. There has been a bit to many changes in the design so it looks like it will fall apart if you look at it to much.

I have had problems to find some kind of power that fits the case. But the solution is hopefully two AAAA batteries and an old step up board from 3 to 5 volts. In the new design I will also skip two wires by running from power off instead of sleep mode both for the CPU and the Zigbee module.

The 3 volt lithium battery has proven ok to drive the CPU but two of them in serie does not have a low enough inner resistance to drive the display. It needs some 140 mA which I thought would be no problem. When going through the data sheets I found I realize I need to find another solution. Perhaps I will go back to a step up converter from 3 to 5 volts.

I made a measurement on the power line to the display. It seems to settle within 400 uS. The spec requires 500 mS from power up to sync signal. The breadboard has a 1 second delay between power up and sync and is working fine. I increased the delay to 2 seconds and now the hand etched board is also working.

The new board is working when breakpoints are set for each acess to the display. I have not found out the reason for this. Luckely I'm not stressed by a short timeplan.

At a first glance the signals on the new board looks ok, but when I run the display a green screen shows up and the display is not turned off before the 6 volts is turned off. I have placed the display on the old board and there it works ok. My guess is that it does not sync in correctly at start or there migth be some difference at the pullup levels. I will have to do some comparison between the two boards without the display connected.

I removed the shortcut by the small Dremel mill I absolutely had to by. I wish there will be more work like that it was quite fun.

During the easter holiday I realized I probably have made a shortcut at the battery holders. I have not seen a lithium battery explode but I like to avoid it. This will give me a good motivation for buing one of those small Dremel drills I always wanted.

Almost all of the components are now mounted. A had to rise the push button a bit to get the rigth feeling. The cost for the components are less than $10, some of them I have no previous experience of. In case of any malfunction the boat will continue with a less oriented skipper.

I use a BC547 to drive the relay for 6 volts to the Oled display. It is also used to fix the PCB to the box. Not recomended for mass production.

The etching took quite a long time, I don't have the strongest etching powder.
Now I go throgh the apartment in a hunt for acetone to get the shiny look of the copper.

I have had som problems with the physical layout.
I had to change the battery holders to surface mount to make it fit.

The Zigbee module and the display will be mounted on top of each other.
In order to do so I had to cut half of the pins to the ZIgbee module.
Before I did that I had a try with the development kit to secure that I still
could set new parameters with pins 11-20 unconected.