Basically, this is a clock counter. This one relies on an external clock so we are running all the counters on an interrupt. The clocking is done on either the rising or falling edge of the clock. The width of the clock cycles can be either 50% or just one main clock cycle (trigger mode). The clock cycles are divided by 2, 3, 4...and so on.
This was my first time playing with the pro mini. After looking at a Moffenzeef Modular, particularly...the a module called, the Count, I figured a counting project would be a good start.
This is pretty similar to 4MS clock divider. In fact, I used their manual to figure out what the counter really should do as far as upbeat/downbeat and trigger modes. The 4MS clock divider has a lot more features. At 95 bucks for the kit, personally, I would just buy that if I was planning a eurorack setup.
I pretty much have only played with this up to the breadboard stage.
Here is the pinout from the pro mini.
The Arduino is going to have limitations when it comes to clock speed. If you are just doing drum beats and sequences, then this is not a problem. If you are hoping to crank it up to audio frequencies, then a little more upfront design is needed.
If your looking for something 10k and above, its probably better to just build a simple circuit from CMOS chips. In that case, your are not really clocking for sequences, but for sub octaves and the like.
This project is based on an external clock (one less thing to manage) which keys off an interrupt routine. The top speed is really going to be based on the size of the interrupt routine. Crank up the frequency...and when it craps out...that is your top freq.
If you were to build this to a working project, consider adding a clock to the circuit. Perhaps a CD40106 based clock or a simple CV controlled LFO.
There are four basic modes for the counting.
- Upbeat Gate - Counting for each divisor starts on the up beat. Duty Cycle 50%.
- Upbeat Trigger - Duty Cycle based on input clock.
- Downbeat Gate - Counting for each divisor starts on the down beat. Gate Duty Cycle 50%.
- Downbeat Trigger Duty Cycle based on input clock.
The first is to count on the upbeat with a 50% duty cycle (gate mode). Note that there is some lead in for the first part of each clock.
Similar, but the clock just outputs a trigger the size of the main clock
In this case, the counting starts on the downbeat. So All clocks fire on the first beat.
Here are a list of modular projects that are similar.
- 4MS clock divider - Most similar
- The Count - Arduino based clock divider with coarse and fine tuning as well as CV controls. Does not need an external clock, and has fun features.
- CV Divider