Designs for vision, a leader in manufacturing specialized optical products used by surgeons and dentists on a daily basis wanted to build a new overhead capacitive touch key panel to be used by dentists all over the USA.
This key panel will consist of 3 sub panels and an Infra-Red remote control. The three sub panels are named top, left and right panels. The left and right panels are mirror images of each other. They contain 8 keys each. They are shade match, molar, gen exam1, +, -, gen exam2 and gen exam3. The top panel has 2 keys for power and lock and 2 hidden keys for configuration. The IR remote will have the same remote keys like the left and right panel and will operate on a single CR2032 coin cell battery.
Their engineers had their hands full dealing with the development of the motor control section and we were called in to not only design the capacitive touch panels but also to design the IR transmitter and receiver design.
The design of an IR transmitter and IR receiver should not be taken lightly. There are several issues to be dealt with for successful IR communication such as
- Noise due to ambient light sources
- Obstacles in the path of message transfer
- Too many binary 1’s or 0’s in transmitted data
The communication protocol chosen to transmit data must deal with all these issues. One such protocol is the RC5 protocol. A modified version of this protocol was used to transmit data to the overhead panel.
The IR transmitter was also designed so that it will generally be in the sleep mode. In this mode, the controller is no longer executing any instructions and the oscillators are turned off. When a button is pressed, the processor wakes up and transmits data to the panel. After about 10 seconds of inactivity, the processor goes to sleep mode again. This ensured a remote that will work for years without requiring the battery to be changed.