Tobiscorner

Funky - Power Optimization

To increase the battery life of the little Funky wireless node I tried reducing the clock frequency of the ATTiny to 1MHz (internal 8MHz + CLKDIV fuse) but when set to 1MHz no communication was possible. With support from the JeeNode Forum I now know that for proper operation of the RFM12 a clock frequency of at least 4MHz is required.
As the current consumption in standby was measured to be about 50uA with a cheap digital volt meter and the DHT11 datasheet states an even higher standby current of min. 100uA for the sensor, "CapnBry" had a nice idea of reducing the power consumption by switching the DHT11 on and off via a port pin. As the DHT needs about 1 seconds after power on to deliver trustworthy measurement results one simply could sleep 1 second short, power on the sensor, sleep for another second, measure the result, turn of the sensor and transmit the data before going to sleep again.

I will test this procedure within the next days and keep you up to date...

Update 1:
Due to the minimum voltage requirement of 3V for DHT11, it is not possible to switch the sensor on and off using a port pin when running from 3,3V.

Update 2:
I bought some 1F/5V supercaps and charged one to 3.6V. The funky could run more than 16h from it reporting the temperature and humidity every 5 minutes. After that 16h the voltage dropped below 3V so the temperature and humidity could not be measured but the funky kept communication for about another 6h. So with a 1F super cap charged to 3.6V the funky can live for about 24h.

Comments (0) 08.03.2012. 22:16

Funky

After ordering some of JeeLabs JeeNode Mirco Modules and playing with them, I designed my own ones, even smaller. They are compatible with the JeeLabs RF12 Library, also use the ATTiny84 but do not include the JeeNode Expansion header. Instead power and some I/Os are routed to a header.
It also has a coin battery holder included and or some space to add a LDO for powering with other sources. On the lower pictures you can see a DHT11 temp. and humidity sensor connected to the funky.

Continue reading Comments (0) 02.03.2012. 22:01

It's working - Papilio One with LED Matrix

Comments (2) 17.09.2011. 12:38

Papilio One

Papilio is an open-source FPGA project intended for education, hobbyists, engineers, or anyone interested in learning Digital Electronics in a friendly community. It offers FPGA development boards and add-on application modules called "Wings", that makes a easy to learn platform for beginners, and powerful design and prototyping tool for engineers. Read more here: Papilio.cc

There is also an Arduino Core for the board that is based on an AVR Softcore processor and comes bundled with a modified Arduino IDE: Arduino Core

To teach my table some brightness levels I would need a fast hardware to do the shifting faster and the papilio seems to be the right hardware for the job. Porting the code and writing the driver core is in progress...

Continue reading Comments (0) 14.09.2011. 09:10

New Blog Engine

Hi all, I moved away from wordpress. Transferring data was a hard job and I hope no bigger failures happened. If you encounter a problem please let Contact me. Tobias

Comments (4) 06.07.2011. 14:37