README.md

# ATKITBreadboardTesting

PIDMotorControl Example includes code for DAC, ADC, PWM, Timer Interrupts, 
PID, Current Control, Encoders w/ interrupts, pins, clock frequency setup, and low pass filters


DAC()<< example in this code is meant only to use DACB due to poor construction
Used to convert digital signals to analog signals - really useful for debugging on scopes

    DAC
    CTRLA - enable a channel on the DAC, and enable DAC
    CTRLB - set DAC to single channel use or dual channel use
    CTRLC - Set the reference voltage
    
    DAC Channel
    DACB.STATUS - used to check if its ready to convert again.
    DACx.CHyDATA - 12 bit value to output



ADC(ADC, ADC_CH, ADC_CH_MUXPOS);
Pass in the ADC you want to use. channel, and the Pin you want to sue for POS side(NEG is gnd here)
Used to convert Analog signals to digital signals for processing. (i.e. - current sensing)

    ADC can be setup in multiple ways- first divide being between single or differential mode
    In the example, it is setup in differential mode W gain.
    
    CTRLA enable ADC
    CTRLB ADC Resolution
    REFCTRL Ref voltage 
    PRESCALER ADC clock prescaler - ADC runs on its own clock- you want to make sure to run it down, otherwise you run into many problems.
    
    ADC Channel
    
    CTRL- channel input mode(DIFFWGAIN in this case) and the gain value, and to start a scan(1<<7)
    remember to check if scan is done being computed before doing again. Value 1<<7 is turned off 
    when scan is done
    MUXCTRL - setting the positive and negative pins.



PWM(Timer, Prescalar, pwm channel, base frequency, desired frequency)
For PWM, you have to setup multiple things. You are using the Timer on the chip,
so you have to setup its period(compare capture value with MAX 65536), its prescalar,
its mode, along with the channel at which to output when the timer hits the compare value.

    Necessary Registers to run minimal PWM
        Timer
        
        CTRLA - prescalar - use the minimum amount in order to preserve as much
        resolution as possible
        CTRLB - Timer mode (Singleslope for PWM-> TC_WGMODE_SINGLESLOPE_gc)
        and the pwm channel on which to output given as TCX_CCXEN_bm type
        PERBUFL & PERBUFH - Hi and lo period values for timer. Timer counts up to
        this value and then restarts back to 0.
        
    
        Timer Channel
        
        CCXBUFH & CCXBUFL - compare value. When the Timer hits this value on its
        count up, it will change the output to low.
        


Timer Interrupts
Also uses Timer (should be obvious given by name ;) ) 
To set up, make sure that interrupts are enabled by including <avr/interrupt.h>,
and calling sei(); and setting the PMIC CTRL pins to each level wanted 
(high, medium, and/or low level interrupts)

Remember to set the pin you want as an output using PORTX.DIRSET register

    Timer
    
    CTRLA - setup prescalar
    PERBUFL & PERBUFH - setup period same as PWM above
    INTCTRLA - initiate the interrupt
    
    then, add a method without return type(not even void) named ISR(TCCX_OVF_vect), 
    where X is your timer number with the contents that you want to loop over.


PID(P,I,D, dt, CONT, MIN & MAX IN & OUT, K)
Typical PID sequence, with some added features. enable CONT in order to have a loop
for a system that is circular (i.e. a 360 degree arm yes vs a 1d elevator no)
Setup mininum and maximum outputs, with integral portion not allowed to go over
the MAX& MIN Outs. Since the derivative portion can be quite noisy run at a very
fast frequency, a low pass filter is automatically applied to the D value,
with K being a constant used to change the low pass filter's response time. See 
low pass filter for details on that. dt is the period of each loop.(1second /frequency)

    crunch(input) logic
    current error = setpoint - current value<<<<<< this is changed if it is CONT. If CONT, find
    the shortest distance to setpoint is the current error.
    total error+= current error;
    derivate error = filter(current error - previous error)
    output = P* current error + I* total Error + D* derivative error
    
    onTarget() logic
    if on target according to acceptable range for more than a 
    certain amount of time, return true

    setAcceptableRange() logic
    set the acceptable range +- where range is sepoint+-acceptable range
    
    setSetpoint()

Current Control(P, I, dt, MAX&MIN IN&OUT)
Basic PI loop. I is used much more than normal, P being used for the initial ramp up.
Same setup as PID loop, but without the derivative term

    crunch(input) logic
    current error = setpoint - current value
    the shortest distance to setpoint is the current error.
    total error+= current error;
    output = P* current error + I* total Error 
    
    onTarget() logic
    if on target according to acceptable range for more than a 
    certain amount of time, return true

    setAcceptableRange() logic
    set the acceptable range +- where range is sepoint+-acceptable range
    
    setSetpoint()

Encoder w/ interrupts/ATKEncoder
Encoders that automatically update based on interrupts running on a certain port.

    PORTX_DIRSET &= ~(PINx_bm | PINy_bm) - set the direction of the two input pins
    PORTX.INTCTRL - set the level of the interrupt(high/med/low)
    PORTX.INTzMASK= set the interrupt of the port towards a certain pin
    PORTX.PINxCTRL = set Pin to trigger on rising or falling edge 
    (make sure one interrupt is set on falling and other on rising edge)
    
    ISR(PORTX_INTz_vect) logic ( 1 for each pin used)
    if pins are different values, add to counter value, if pins are the same, subtract
    This is due to the nature of encoders and how they count. If running clockwise,
    the values line up, and if counter clockwise they dont line up(the values are 90 degrees away
    from each other)
    


Basic Pin I/O
    PORTX_DIRSET - set the direction of each port- 0 for input 1 for output
    PORTX_DIRTGL - toggle direction 
    PORTX_DIRSET/CLR - set or clear direction of each port
    
    PORTX_OUTSET/TGL/CLR- set/toggle/clear output to high or low
    
clock frequency setup
Don't really understand this, just copy paste. Used to set clock to 48 Mhz

	 OSC.XOSCCTRL = OSC_XOSCSEL_XTAL_256CLK_gc | OSC_FRQRANGE_12TO16_gc; // select external source
	 OSC.CTRL = OSC_XOSCEN_bm; // enable external source
	 while(!(OSC.STATUS & OSC_XOSCRDY_bm)); // wait for external
	 OSC.PLLCTRL = OSC_PLLSRC_XOSC_gc | OSC_PLLFAC0_bm | OSC_PLLFAC1_bm; // select external osc for pll, do pll = source * 3
	 //OSC.PLLCTRL = OSC_PLLSRC_XOSC_gc | OSC_PLLFAC1_bm; // pll = source * 2 for 32MHz std clock
	 OSC.CTRL |= OSC_PLLEN_bm; // enable PLL
	 while (!(OSC.STATUS & OSC_PLLRDY_bm)); // wait for PLL to be ready
	 CCP = CCP_IOREG_gc; // enable protected register change
	 CLK.CTRL = CLK_SCLKSEL_PLL_gc; // switch to PLL for main clock
 
 

low pass filters(K)
Used to clean a noisy signal. meant to be run at a fast frequency, since (1-2^-k)takes many
clock counts to settle.
Algorithm- output = y(n) = (1-2^-k)(y(n-1)) + (2^-k)(x(n)) << y(n) output, x(n)new input, n current clock count

    filter(input)
    give in new input, and returns in output



























Currently two examples of working code using Atmel Studio
for the Automota Kit Breadboard board

DACExample
Outputs a sine wave out of the PB2 port using DACB


PWMControl
Outputs a pwm signal ranging from 0-100% duty cycle at 20khz