Weather Station & Clock

[Janke]

Friends -

Having ironed out the bugs in my previous project (a huge 16x120 pixel LED matrix display for my model railroad),
I'm now working on a smaller, 16x40 pixel Weather Station & Clock using the same MAX7219 LED modules.

This was, of course, inspired by the DHTHUM and DHTTEMP commands in the EzSBC1 !
I plan to publish the BASIC code here, when completed.

The enclosed photo shows the different display modes (some are simulated, I'm still waiting for a sensor from eBay...)
Note the graphic representation of trends in temperature, humidity and barometer pressure.
There are two graphs: the left one shows the trend over 14 days, the right one over 12 hours.

I have one question for readers:

Has anyone interfaced the "BMP180" atmospheric pressure sensor to the EzSBC1 ?

You'll easily find the BMP180 datasheet on the web, but the provided sample code is pretty complicated -
so if someone here has already done it, why re-invent the wheel?

[Janke]

Here are a couple of photos of the hardware:

The EzSBC1 is mounted in a socket on a small perforated prototyping board, together with two 74ACT08 ICs, each containing four 2-input AND gates. They function as level converters from the processor's 3.3 volt logic levels to the 5 volt levels required by the MAX7219 modules. I could have used six simple non-inverting buffers in a single IC, but did not have any handy, so I used the AND gates instead. A 100 uF electrolytic capacitor prevents spikes in the 5 volt line. The connector at left goes to the LED matrix, the one at right to the two sensors: an AM2320 humidity & temperature sensor, and a BMP180 pressure sensor. Still missing: the RTC backup battery holder.

The ten LED matrix modules are connected in two rows of five each, connected as intended, not diagonally as in my previous project. Note the bypass capacitors, and the bridging of the GND and VCC lines at left, as well as 3- and 5-pin connectors at right. These are connected to the EzSBC1 board.