Incremental 2 Pulse converter
I2P converter is designed for direction detection (CCW or CCW) of rotary encoders ("neverless switches") and generation of the corresponding signal (pulses) like from "classic" switches/buttons. This converter was successfully tested with encoders from companies CTS, Bourns, PIHER and Panasonic. The aim is replacement of buttons "+" / "-", up / down, .. or for frequency tuning HAM radios, generators, etc. A similar solution is used in most handheld HAM radios (for ex. Yaesu company).
Basic technical parameters
- Power: 5 V
- Current: less than 10 mA
- Oscilátor: interní RC cca 4 MHz
- Type of encoders: mechanical — 2 channels (fázově posunuty)
- Time of pulses: 10 ms or 25 ms
- Numer of pulses: max. 65 (resp. 33) / 1 s
Function description and firmware
All necessary activities for the detection and subsequent pulses generation CW (right) or CCW (left) provides the microcontroller firmware. It is a inexpensive type PIC12C508 Microchip in DIP8 housing. 2 channels (A, B) of mechanical incremental encoders are used as input signal. To determine the direction of rotation is necessary to be phase shiffted (see timing).
Time Tps must be min. 5 ms (can be changed in firmware) and is used for elimination of transient (from the mechanical contacts) in the channel in which there was a change of logical level. After that the MCU already waiting for a change in the other channel, followed by generation CW or CCW pulse.
The duration of this pulse (Tcw, respectively Tccw) can be set to 25 ms by log. 0 on MCU pin 4, but default time 10 ms will be mostly good. This input is set to log. 1 via internal pull-up resistors in MCU (like channels A and B). Also the other advantage - an internal RC oscillator (calibrated by Microchip) is used. Its accuracy is good for this application.
Because the construction consist only one component (MCU), the PCB layout was not designed. The source code and hex firmware file is distributed free for HAM community usage. Commercial production is prohibited without the permission of author.
References
- [1] www.microchip.com
- [2] www.ic-prog.com
Pictures
Files
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