December 2004, Issue 173

H8/38024F-Based Programmable Timer

NO PRETZELS ALLOWED

Yoga is Sanskrit for “yoke,” or “union.” With origins dating back more than 5,000 years, yoga encompasses elements of an entire lifestyle geared toward spiritual practice. Intended as a method to unite the mind, body, and spirit, it’s currently one of the most popular ways to stay in shape and reduce stress. There are numerous yoga styles—some ancient, some modern. Each has a different approach to achieving the mind-body-spirit union. The choice of which to pursue is usually guided by personal preference because one style is not necessarily better or worse than another.

Most who are unfamiliar with yoga think of it as the contortionist exercises they’ve heard about at the local health club. This is usually the popular style known as Hatha yoga, which is more physically oriented. It consists mainly of a series of poses, or asanas, and breathing techniques, known as pranayama. Some other common yoga styles also focusing on physical practices are Ashtanga and Power yoga, which can be more intense than Hatha. Dedicated spiritual seekers also may be familiar with a wide variety of yoga styles based more on behavior than physical practices. Karma yoga, for example, is based on service to others.

For the past couple of years I have been practicing Kundalini yoga, which is focused on controlled breathing during the application of carefully designed stresses and relaxation to internal organs. Most of the poses are stretches done while sitting or lying down, rather than the complex poses of Hatha yoga. Each session consists of one or more kriyas, which are combinations of several practices including breathing, poses, sounds, meditation, and relaxation. There are hundreds of predetermined kriyas, each with several steps that must be accurately timed to achieve the desired effect.

The class I’m in has fewer than a dozen people in it, and has a peaceful, meditative atmosphere. Aside from an occasional late arrival, the only noticeable disruption is the beeping of the timer at the end of each step. It actually bothers our teacher more than us, and she asked me several times if I knew of any alternatives. The timeout beeper is the problem. Every timer she’s found starts beeping at the end of the time interval and won’t stop until she presses a button. Often, she will not be in a position to hit the button immediately, so the class must listen to the insistent timer for a while. In addition, most timers generate audible feedback after a button is pressed. This results in a pattern of beeps and boops every few minutes each time my teacher restarts it.

At first, I thought there must be something out there that other yoga teachers use during their sessions, but neither my teacher nor I were able to find anything. It occurred to me that if there were a way to preset the entire routine in advance, it would allow my teacher to spend more time focusing on the class, rather than having to deal with the timer at the start of each step. I wondered whether a modified kitchen timer would be useful or if I needed to design something from scratch. Then the Renesas H8 Design 2003 contest came along. I learned that some Renesas MCUs included features perfect for a timer, so I felt it was time to come up with a real solution.