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Use your spare Raspberry Pi to measure soil moisture

One thing about successful plant growing it to keep proper moisture level of soil. This is even more important when plant is pot where it has no way reach water source. To avoid drying out or over-watering – a simple electronics can help. Of course this can be achieved with simple 555 timer based buzzer sensor. But why bother if there is a spare Raspberry Pi. Jeremy Blythe shared his build where his raspberry Pi successfully monitors his plants. He used soil moisture sensor brick which gives analog signal. Raspberry Pi cannot read analog, so there is an external ADC (MCP3008) used which interfaces via SPI. Jeremy put external circuit on a sticky breadboard which stuck nicely to plexiglass. On top of RasPi he placed Adafruit RGB negative 16×2 LCD… Continue reading

Controlling hardware SPI on Raspberry Pi using Python

Controlling hardware SPI on Raspberry Pi using Python

Raspberry Pi has an I/O header available for many interesting hacks. In other hand a Python is a great scripting/programming language that allows programming things pretty quickly. So it is always nice to have a good arsenal of tools around when you need. Louis shares his findings and experiments on how to access hardware SPI on Raspberry Pi through Python. The way he does it is that he uses C extensions to Python. The fact is that there is already a hardware SPI library written in C. All you need is to access it from python. C Extension in python gives access to functions from C based module. A minor tweak is required [More about extending Python with C]. Once you get simple SPI echoing working there is a simple… Continue reading