chASM2 - Control Hardware /with/ ASM using lightweight C

chASM2 is a revsions of chASM, with the same goals, but using C instead of C++ The speed and Storage/Memeory overhead has been improved, this is especially useful for weak MCUs like the Attiny Series

This library natively supports and has been tested with:

• Arduino Uno
• Arduino Nano
• Arduino Mega
• Ardunio Pro Mini
• ATTiny Family

chASM2 Should work on any platform that supports the post Arduino 1.0 IDE method of digitalWrite/digitalRead, since chASM2 relies on the same digitalPinToMask etc functions that the built-in methods use too.

To improve speed and memory overhead, chASM2 has no safety in terms of NULL checking, or malfored data during execution - Due to this, it's recommended you are familiar with how C works before using this library

Usage

When using chASM2, you need to define a chasm_t struct to stand in as a pin, you can then pass that struct pointer to functions to perform IO Operations

To declare a chASM2 Pin

chasm_t pin;

//In Setup or other function before using he pin
//13 is the pin number, can be anything supported by the hardware
chasm_init(&pin, 13);

To set the mode of the chASM2 Pin

chasm_setmode(&pin, t_MODE); //Supports 0/1 or INPUT, OUTPUT and INPUT_PULLUP

To Read and Write a bit of the chASM Pin

chasm_write(&pin, bool); //Supports HIGH/LOW 0/1
chasm_read(&pin); //Returns bool, 1/0

Notes

Speed Measurements:

Testing was done an an offical Arduino Uno R3 All tests have been conducted with a Racal-Dana 9914 VHF Freq. Counter, which has been calibrated to +/- 8Hz accuracy

Psuedo Code:

void loop() {
	write( HIGH );
	write( LOW );
}

digitalWrite: 111.7KHz
chASM2: 661.8KHz 5.92x faster

void loop() {
	write( HIGH );
	write( LOW );
	write( HIGH );
	write( LOW );
	write( HIGH );
	write( LOW );
	write( HIGH );
	write( LOW );
}

digitalWrite: 112.8KHz
chASM2: 705.0KHz 6.25x faster

Storage Profiling

Due to some functions being inlined, they take some amount of Program Storage:
With chASM2, both write(HIGH) and write(LOW) take 18 bytes per call, or 36 bytes for a write(HIGH), write(LOW) toggle operation. This is an improvement over chASM (v1) - also consider that this is a consistant and linear overhead, whereas the first call to digitalWrite takes 160 bytes, and all subsequent calls take 0 to 20 bytes, averging 10 bytes per call.

This means chASM2 is far more efficient with Program Storage; around 9 calls to chASM2 will take the same amount of space as a the first call to digitalWrite.

TODO

• Look into analogRead support for this library.

---

(c) ADBeta 2023 This software is under the GPL v2.0 licence. Please read the LICENCE file