Category: Encoder

Using a 100PPR encoder with the KD8CEC firmware may cause some issues as the firmware can’t keep up with the pulse train from the encoder.

Sascha Bonnet suggests some simple code modifications make a big difference. He replaced two commands (“millis” to “micros”) in the KD8CEC’s source code and my encoder worked.   Here’s his code for you to use as a template for editing the KD8CEC arduino sketch:

1. int enc_read(void) {
2.   int result = 0;
3.   byte newState;
4.   int enc_speed = 0;
6.   unsigned long start_at = millis();
8.   while (millis() – start_at < 50) { // check if the previous state was stable
9.     newState = enc_state(); // Get current state  
11.     if (newState != enc_prev_state)
12.       delayMicroseconds(1);
14.     if (enc_state() != newState || newState == enc_prev_state)
15.       continue;
16.     //these transitions point to the encoder being rotated anti-clockwise
17.     if ((enc_prev_state == 0 && newState == 2) ||
18.       (enc_prev_state == 2 && newState == 3) ||
19.       (enc_prev_state == 3 && newState == 1) ||
20.       (enc_prev_state == 1 && newState == 0)){
21.         result–;
22.       }
23.     //these transitions point o the enccoder being rotated clockwise
24.     if ((enc_prev_state == 0 && newState == 1) ||
25.       (enc_prev_state == 1 && newState == 3) ||
26.       (enc_prev_state == 3 && newState == 2) ||
27.       (enc_prev_state == 2 && newState == 0)){
28.         result++;
29.       }
30.     enc_prev_state = newState; // Record state for next pulse interpretation
31.     enc_speed++;
32.     delayMicroseconds(1);
33.   }

Reference

John Scherer came across an interesting, i2c addressable rotary encoder board that allows you to connect encoders in just about any configuration.

The board has pins for digital or ADC I/O, has 256 bytes of eeprom, pads for setting each encoders i2c address, and works from 3.3 – 5V DC.   For something like the µBitx, this could be an easy way to add additional physical I/O (i.e. knobs).

There is also a video that gives a pretty good overview of how they work.

John VK2ETA suggests that on a read of the manual it appears the 256 registers are at one I2C address, and are divided between control registers and EEPROM addresses (two banks of 128 bytes).

The current implementation has the current modes for the encoder:

A. Relative, where the counter keeps the number of steps since last read. Reading it resets the counter to zero. Useful for frequency tuning in our case.

B. Absolute
B1. Without limits.
B2. With user defined limits
B2.1. No wrap around, like a potentiometer, hard stops at the limits.
B2.2 With wrap around, goes back to low limit if high limit is exceeded and vice-versa.

The encoder push button events are:
– button down
– button up
– double-press with user selectable double-press interval.

Current consumption is listed at less than 2mA plus LED current if used.

The board mounted PIC controller’s program is open source so it can be customized as well.

Tom, WB6B believes they keep a counter in the PIC chip that is on each board, so each time you check the status of an encoder board it will tell you how many encoder pulses took place since the last time you polled the data. This should greatly relax any timing issues.

Reference

This optical encoder (widely available on eBay or Aliexpress in black or silver) has been used by some constructors as a replacement to the standard mechanical encoder supplied with the µBITx kit.   It is a 100ppr encoder (whereas the one supplied with the µBITx is 24PPR) so may not work perfectly with either the default firmware supplied by HF Signals or Ian Lee KD8CEC firmware (i.e. you may need to experiment with the code for generating the VFO).

With the detent mechanism removed to allow free turning the encoder gives a very smooth tuning action.   With the encoder able to spin freely the protruding crank handle will always come to rest in the down position so it too has to be removed.

The main complaint with these encoders is the detent feature.  To remove the detent, here are the instructions from Robert GM4CID:

Remove the knob handle, then, using a heat gun or hair dryer heat the silver knob insert to soften the adhesive and carefully pry off that silver insert to reveal retaining screws that can be removed. The mechanism will now come apart and you can remove the detent. Replace everything but not the handle.

Reference