I have purchased an Orange Pi Zero (OPi0), to replace the Raspberry Pi that controls my solar panel array, wind turbine and battery bank. It basically switches the turbine / panels in and out of circuit using relays, depending on the state of charge of the battery bank and the amount of wind / sunshine available.
The battery voltage and charge / discharge currents are monitored by an arduino nano clone, because the OPi0, like the Raspberry Pi it replaces, does not have an Analogue to Digital Converter, (ADC). The voltage is measured using a pair of resistors as a potential divider to bring the voltage down to the 0 - 3.3 volt range of the arduino ADC; And the current measuring ADCs use ACS712 hall effect sensors. The arduino also records the ambient temperature using a DS18B20, and the windspeed using a Maplin Anemometer (Code: N76NF).
The arduino is connected to one of the three UARTs (universal asynchronous receiver-transmitter), or just plain serial ports, (think old-fashioned USB), on the Orange Pi Zero, and it uses this connection to send the sensor readings to the Orange Pi Zero every few seconds. The Orange Pi Zero uses this sensor information to keep the battery bank charged at an optimal level and prevent excessive battery discharge or overcharge, either of which will shorten the battery life considerably. This sensor data is also logged to an SQL database for future analysis.
The Orange Pi Zero is an open-source single-board computer. It can run Android 4.4, Ubuntu, Debian. It uses the AllWinner H2+ SoC,(System On a Chip), and has 256MB/512MB DDR3 SDRAM (The 256MB version is the Standard version).
I chose to run the Armbian release of Debian Jessie from www.armbian.com because after testing various alternatives, it seemed the better choice, mainly because it is being actively developed and because I have previous experience running Debian. Also, the Debian image offered by www.orangepi.org had a bug which caused the CPU to overheat. I should point out that this is run headless, there is no keyboard, monitor or mouse attached, any and all operations, programming or maintenance is done over the network from another computer.
- CPU - H2 Quad-Core Cortex-A7 @ 1.2GHz
- GPU - Mali 400MP2 @ 600MHz
- USB - One USB 2.0 HOST + One USB 2.0 OTG
- WiFi - IEEE 802.11 b/g/n
- GPIO - 26 Pins Header, compatible with Raspberry Pi
- Memory - 256MB/512MB DDR3 SDRAM(Shared with the GPU)
- Network - 10/100M Ethernet
- PCB dimensions - 48 mm x 46 mm
- Weight - 26 grams (or almost a whole ounce)
TL;DR - Conclusion.
A great little computer for either simply experimenting with, or using as the heart of your next project. It has lots of general purpose input/output pins, is compatible with the original 26 pin header on a Raspberry Pi, which means it can read sensors, flash LEDs, control relays, play music and run python. Absolutely ideal as a building block to help you achieve world domination in no time at all. Incredibly cheap too and can be purchased online from the Orange Pi Shop. Mine has clocked up 190 days since its last reboot, but it is not internet facing and so I've been a bit slack applying security bug-fixes and patches.