Today most bicycles are equipped with lamps, generators. Probably with trip counters and probably more. Often these are there and to access them you need to to this from different places. Bicycle computers are small and most often with watch size LCD which may be hard to spot – especially at night. Aleator777 decided to change this by building bike dashboard which is big, bright and easy to use.
As base computer he’s chosen Arduino Micro which controls all sensors and lamps. Bicycle lamps are driven through n-channel MOSFETs. 12V power supply is made of eight 1.2V batteries. Bicycle speed is read with reed switch which pulses go through debouncer circuit made of RC and then goes through 74HC14 Hex Inverting Schmidt Trigger. Speedometer is built of 6 LEDs driven directly by Arduino digital pins. Designed dashboard with Adobe Illustrator which then was laser cut out of plywood. The box is quite big that sits on handlebar. It also fits the front halogen lamp. After it’s been finished, there came some ideas for upgrades that might be: sound system, turn signals, more resolution on speedometer and even LCD odometer. In my opinion I would probably think of adding rechargeable battery that could be charged with on-wheel generator also headlamp could be power LED that is more efficient than halogen.
Humidor is a device that tries to keep humidity and temperature at desired level. Normally they are stand alone devices that can be refilled with water to keep humidity at level. Dzzie decided to add DHT22 humidity and temperature sensor to it and along with Arduino log this data to webserver.
He wrote a PHP script that records humidity and temperature data to database every 20 minutes. There is also a trigger mechanism which sends an email alert once one of parameters gets out of safe range. Humidor sensor is run with Arduino with LCD shield. It has a feature to record time when water is refilled. If you use humidor in sensitive area – then accessing data online might help a lot.
Xbee is a great radio module to communicate between devices wireless. Steven shared his extensive work on Xbee communication in API mode which was included in his Masters thesis. His setup uses Xbee module on each end. On one end he connect module to PC with Xbee USB adapter, another part is attached to Arduino.
The fun part begins with software. He’s chosen API mode because there are several advantages over regular modes. It frees from switching in to command mode in order to change configuration options, also message address can be set on fly, messages packets come with RSSI (Received Signal Strength Indicator) and feedback message is sent on successful transmission. He used Digi X-CTU software to work with message frames which is robust on building API frames. Once succeeded Steven moved to python code. He was able to talk to Xbee module by using PySerial library. The code takes care of sending and receiving message frames. Same applies to Arduino part which also has to be able to receive and send message packets in API mode. For those who want to dig deeper, there is a source code available in Github.
Solar panels are most effective when facing sun directly. So if you want to get most energy, you need to track sun trajectory in order to keep panels always facing towards the sun. Actually this is fairly easy task. In this solution vigneshraja shares setup built of couple light dependent resistors (LDR) and single motor to track sun.
Tracker is built on MSP430G2231 microcontroller that sit in Launchpad. Interesting thing is that two LDRs are in stationary position that determine sun position by comparing their values. Motor is driven through H-Bridge motor controller. Such solution is great for near equator locations, but in other areas sun wont travel directly above, so probably more suitable tracker should have two motors controlling both angles to point sun directly.