Stepper motor driver with pulse and direction interface

Well, the average resolution of setInterval is actually very high (1 uS) but the speed of execution of JavaScript is really going to cause you problems - so while you could maybe get nearer 8kHz with a few lines of the inline assembler, other bits of JavaScript that run will get in the way of it.

It's a bit difficult really... You can get an accurate, very high pulse rate using the built-in timers and analogWrite, but crucially you won't be able to accurately count how many pulses have been sent out.

So if you really want the higher speeds with Espruino I guess you have three options - none of which is great:

• Use peek and poke to set up one of the hardware timers as a counter, then use that counter to count the number of pulses that have been sent with the analogWrite command.
  
• Some of the hardware timers have a register for 'repeat count'. I don't know if you could somehow set/query that with peek and poke in order to make sure that you sent out only the amount of pulses that you wanted.
  
• Modify Espruino's source so that you can use the software timer (in jstimer.c) to do what you want. It's what is used for digitalPulse/Waveform/etc and is capable of sending repeated pulses at relatively high (~50kHz?) rates. You'd have to add something such that it could keep track of how many pulses had been sent, and so that you could also change the interval between them.