Sous Vide Part 1: What and Why?

I was introduced to the concept of sous-vide cooking one day while listening to Science Friday. In a nutshell, sous-vide cooking involves vacuum packing your food (usually meats) and placing them into a temperature controlled water bath at lower-than-normal cooking temperatures for longer-than-normal cooking times.

Efficiently Reading Quadrature With Interrupts

Once you start wanting to control the position of a motor through feedback control, you will likely end up using a rotary encoder as the feedback device. Encoders can be broadly categorized as:

• Absolute position
• Incremental position

Absolute position encoders will tell you what the angular position is all the time, even between power cycles. Most use "grey code" (a modified form of binary) with several "tracks" (bits) to read position.

Incremental position encoders will tell you what the angular position is, but only relative to where it was when you started paying attention (usually on power-up). Two common types of incremental outputs are:

• Incremental (clever name)
• Quadrature

Incremental is rather useless for position control because it doesn't give you any information about what direction you are turning, just that you are turning. Quadrature encoders give you direction as well as incremental position. This article deals with efficiently reading quadrature output on an Arduino by utilizing external interrupts and some AVR bare-bones code.