PICAXE chips
So Ive been playing around a bit with the PICAXE Micro controller. Its a pretty impressive little chip.
Basically, its a PIC chip with a bootstrap program on it. You can’t use just any PIC, you order the chip from the makers of PICAXE. On the plus side, you have a “kernel” on the chip that makes programming it a breeze. Just a serial connection from your serial port on the computer is needed. Because of this, you can build a programmer with just a few parts. Additionally, the BASIC is really simple.
The downside is that the kernel overhead is kinda high. Even though a 8 pin PIC runs at 4Mhz, that translates to about 10,000 BASIC commands a second.
To get started I just bought this. Its entry level. The cord is pretty much all you need. Once you have that, you can build a programming interface into any project you make with a resistor and a 1/8 inch stereo plug.
Because it is so darned easy, I figured it would be useful in my general exploration of noise making circuits.
My projects so far are here.
So far, it appears that its not so good for making audio. There is a sound command, it can be used intelligently, but for the most part, its better suited for controlling things. There are no timed interrupts and for the most part, its all synchronous. If you run a one second basic command to play a note…the processor is tied up for a second.
Still, I have hope I can find useful applications for this chip. CMOS provides good building blocks, but you can simply things with code easily. Unfortunately, CMOS is fast and the PICAXE is not.
Next Ill look at the PICAXE as a DCLFO. I found a good start at using PICAXE chips and shift registers here.
Seems like could make a decent LFO (with waveforms) based on shift registers.
Follow me. Using an 8 bit shift register and a resolution of 16 samples a second, an LFO with a max of 4 hz would require 10000/ ( ( 8 bits * 16 values per waveform * 4 hz)) = 19 basic instructions per interrupt.
Thats doable for an LFO considering most of the time, all we are doing is pulsing a bit. It will be grainy, but doable. For the most part, each interrupt would be a pulsing a bit. Reading a READADC would be once in a blue moon. Anyway…in the next week Ill figure out if I can do it or not.
Applications? Well…who knows.
Later Ill get into the PWM capabilities of the PICAXE. This can be filtered to get an analog value