Adding new kishsaver strobe map for new PCB revision

[kiibohd-controller.git] / Scan / avr-capsense / scan_loop.c

/* Copyright (C) 2011-2013 by Joseph Makuch
 * Additions by Jacob Alexander (2013)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3.0 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

// ----- Includes -----

// Compiler Includes
#include <Lib/ScanLib.h>

// Project Includes
#include <led.h>
#include <print.h>

// Local Includes
#include "scan_loop.h"



// ----- Defines -----

// TODO dfj defines...needs commenting and maybe some cleaning...
#define MAX_PRESS_DELTA_MV 450 // As measured from the Teensy ADC pin
#define THRESHOLD_MV (MAX_PRESS_DELTA_MV >> 1)
//(2560 / (0x3ff/2)) ~= 5
#define MV_PER_ADC 5
#define THRESHOLD (THRESHOLD_MV / MV_PER_ADC)

#define STROBE_SETTLE 1

#define TEST_KEY_STROBE (0x05)
#define TEST_KEY_MASK (1 << 0)

#define ADHSM 7

#define RIGHT_JUSTIFY 0
#define LEFT_JUSTIFY (0xff)

// set left or right justification here:
#define JUSTIFY_ADC RIGHT_JUSTIFY
#define ADLAR_MASK (1 << ADLAR)

#ifdef JUSTIFY_ADC
#define ADLAR_BITS ((ADLAR_MASK) & (JUSTIFY_ADC))
#else // defaults to right justification.
#define ADLAR_BITS 0
#endif

// full muxmask
#define FULL_MUX_MASK ((1 << MUX0) | (1 << MUX1) | (1 << MUX2) | (1 << MUX3) | (1 << MUX4))

// F0-f7 pins only muxmask.
#define MUX_MASK ((1 << MUX0) | (1 << MUX1) | (1 << MUX2))

// Strobe Masks
#define D_MASK (0xff)
#define E_MASK (0x03)
#define C_MASK (0xff)

// set ADC clock prescale
#define PRESCALE_MASK ((1 << ADPS0) | (1 << ADPS1) | (1 << ADPS2))
#define PRESCALE_SHIFT (ADPS0)
#define PRESCALE 3

// Max number of strobes supported by the hardware
// Strobe lines are detected at startup, extra strobes cause anomalies like phantom keypresses
#define MAX_STROBES 18

// Number of consecutive samples required to pass debounce
#define DEBOUNCE_THRESHOLD 5

#define MUXES_COUNT 8
#define MUXES_COUNT_XSHIFT 3

#define WARMUP_LOOPS ( 1024 )
#define WARMUP_STOP (WARMUP_LOOPS - 1)

#define SAMPLE_CONTROL 3

#define KEY_COUNT ((MAX_STROBES) * (MUXES_COUNT))

#define RECOVERY_CONTROL 1
#define RECOVERY_SOURCE  0
#define RECOVERY_SINK    2

#define ON  1
#define OFF 0

// mix in 1/4 of the current average to the running average. -> (@mux_mix = 2)
#define MUX_MIX 2

#define IDLE_COUNT_MASK 0xff
#define IDLE_COUNT_SHIFT 8

// av = (av << shift) - av + sample; av >>= shift
// e.g. 1 -> (av + sample) / 2 simple average of new and old
//      2 -> (3 * av + sample) / 4 i.e. 3:1 mix of old to new.
//      3 -> (7 * av + sample) / 8 i.e. 7:1 mix of old to new.
#define KEYS_AVERAGES_MIX_SHIFT 3



// ----- Macros -----

// Make sure we haven't overflowed the buffer
#define bufferAdd(byte) \
                if ( KeyIndex_BufferUsed < KEYBOARD_BUFFER ) \
                        KeyIndex_Buffer[KeyIndex_BufferUsed++] = byte

// Select mux
#define SET_FULL_MUX(X) ((ADMUX) = (((ADMUX) & ~(FULL_MUX_MASK)) | ((X) & (FULL_MUX_MASK))))



// ----- Variables -----

// Buffer used to inform the macro processing module which keys have been detected as pressed
volatile uint8_t KeyIndex_Buffer[KEYBOARD_BUFFER];
volatile uint8_t KeyIndex_BufferUsed;


// TODO dfj variables...needs cleaning up and commenting

// Variables used to calculate the starting sense value (averaging)
uint32_t full_avg = 0;
uint32_t high_avg = 0;
uint32_t  low_avg = 0;

uint8_t  high_count = 0;
uint8_t   low_count = 0;


uint8_t ze_strober = 0;

uint16_t samples[MUXES_COUNT];

uint8_t cur_keymap[MAX_STROBES];

uint8_t keymap_change;

uint16_t threshold = THRESHOLD;

uint8_t column = 0;

uint16_t keys_averages_acc[KEY_COUNT];
uint16_t keys_averages    [KEY_COUNT];
uint8_t  keys_debounce    [KEY_COUNT]; // Contains debounce statistics
uint8_t  keys_problem     [KEY_COUNT]; // Marks keys that should be ignored (determined by averaging at startup)

uint8_t full_samples[KEY_COUNT];

// TODO: change this to 'booting', then count down.
uint16_t boot_count = 0;

uint16_t idle_count = 0;
uint8_t idle = 1;

uint8_t error = 0;
uint16_t error_data = 0;

uint8_t total_strobes = MAX_STROBES;
uint8_t strobe_map[MAX_STROBES];

uint8_t dump_count = 0;



// ----- Function Declarations -----

void dump( void );

void recovery( uint8_t on );

int sampleColumn( uint8_t column );

void capsense_scan( void );

void setup_ADC( void );

void strobe_w( uint8_t strobe_num );

uint8_t testColumn( uint8_t strobe );



// ----- Functions -----

// Initial setup for cap sense controller
inline void scan_setup()
{
        // TODO dfj code...needs cleanup + commenting...
        setup_ADC();

        DDRC  = C_MASK;
        PORTC = 0;
        DDRD  = D_MASK;
        PORTD = 0;
        DDRE  = E_MASK;
        PORTE = 0 ;

        // Hardcoded strobes for debugging
        // Strobes start at 0 and go to 17 (18), not all Model Fs use all of the available strobes
        // The single row ribbon connector Model Fs only have a max of 16 strobes
#define KISHSAVER_STROBE
//#define KISHSAVER_OLD_STROBE
//#define TERMINAL_6110668_OLD_STROBE
//#define UNSAVER_OLD_STROBE
#ifdef KISHSAVER_OLD_STROBE
        total_strobes = 9;

        strobe_map[0] = 2; // Kishsaver doesn't use strobe 0 and 1
        strobe_map[1] = 3;
        strobe_map[2] = 4;
        strobe_map[3] = 5;
        strobe_map[4] = 6;
        strobe_map[5] = 7;
        strobe_map[6] = 8;
        strobe_map[7] = 9;
        strobe_map[8] = 15; // Test point strobe (3 test points, sense 1, 4, 5)
#elif defined(KISHSAVER_STROBE)
        total_strobes = 9;

        strobe_map[0] = 15; // Kishsaver doesn't use strobe 0 and 1
        strobe_map[1] = 14;
        strobe_map[2] = 13;
        strobe_map[3] = 12;
        strobe_map[4] = 11;
        strobe_map[5] = 10;
        strobe_map[6] = 9;
        strobe_map[7] = 8;
        strobe_map[8] = 2; // Test point strobe (3 test points, sense 1, 4, 5)
#elif defined(TERMINAL_6110668_OLD_STROBE)
        total_strobes = 16;

        strobe_map[0] = 0;
        strobe_map[1] = 1;
        strobe_map[2] = 2;
        strobe_map[3] = 3;
        strobe_map[4] = 4;
        strobe_map[5] = 5;
        strobe_map[6] = 6;
        strobe_map[7] = 7;
        strobe_map[8] = 8;
        strobe_map[9] = 9;
        strobe_map[10] = 10;
        strobe_map[11] = 11;
        strobe_map[12] = 12;
        strobe_map[13] = 13;
        strobe_map[14] = 14;
        strobe_map[15] = 15;
#elif defined(UNSAVER_OLD_STROBE)
        total_strobes = 14;

        strobe_map[0] = 0;
        strobe_map[1] = 1;
        strobe_map[2] = 2;
        strobe_map[3] = 3;
        strobe_map[4] = 4;
        strobe_map[5] = 5;
        strobe_map[6] = 6;
        strobe_map[7] = 7;
        strobe_map[8] = 8;
        strobe_map[9] = 9;
        strobe_map[10] = 10;
        strobe_map[11] = 11;
        strobe_map[12] = 12;
        strobe_map[13] = 13;
#else
        // Strobe detection
        // TODO
#endif

        // TODO all this code should probably be in scan_resetKeyboard
        for ( int i = 0; i < total_strobes; ++i)
        {
                cur_keymap[i] = 0;
        }

        // Reset debounce table
        for ( int i = 0; i < KEY_COUNT; ++i )
        {
                keys_debounce[i] = 0;
        }

        // Warm things up a bit before we start collecting data, taking real samples.
        for ( uint8_t i = 0; i < total_strobes; ++i )
        {
                sampleColumn( strobe_map[i] );
        }


        // Reset the keyboard before scanning, we might be in a wierd state
        // Also sets the KeyIndex_BufferUsed to 0
        scan_resetKeyboard();
}


// Main Detection Loop
// This is where the important stuff happens
inline uint8_t scan_loop()
{
        capsense_scan();

        // Error case, should not occur in normal operation
        if ( error )
        {
                erro_msg("Problem detected... ");

                // Keymap scan debug
                for ( uint8_t i = 0; i < total_strobes; ++i )
                {
                        printHex(cur_keymap[strobe_map[i]]);
                        print(" ");
                }

                print(" : ");
                printHex(error);
                error = 0;
                print(" : ");
                printHex(error_data);
                error_data = 0;

                // Display keymaps and other debug information if warmup completede
                if ( boot_count >= WARMUP_LOOPS )
                {
                        dump();
                }
        }


        // Return non-zero if macro and USB processing should be delayed
        // Macro processing will always run if returning 0
        // USB processing only happens once the USB send timer expires, if it has not, scan_loop will be called
        //  after the macro processing has been completed
        return 0;
}


// Reset Keyboard
void scan_resetKeyboard( void )
{
        // Empty buffer, now that keyboard has been reset
        KeyIndex_BufferUsed = 0;
}


// Send data to keyboard
// NOTE: Only used for converters, since the scan module shouldn't handle sending data in a controller
uint8_t scan_sendData( uint8_t dataPayload )
{
        return 0;
}


// Reset/Hold keyboard
// NOTE: Only used for converters, not needed for full controllers
void scan_lockKeyboard( void )
{
}

// NOTE: Only used for converters, not needed for full controllers
void scan_unlockKeyboard( void )
{
}


// Signal KeyIndex_Buffer that it has been properly read
// NOTE: Only really required for implementing "tricks" in converters for odd protocols
void scan_finishedWithBuffer( uint8_t sentKeys )
{
        // Convenient place to clear the KeyIndex_Buffer
        KeyIndex_BufferUsed = 0;
        return;
}


// Signal KeyIndex_Buffer that it has been properly read and sent out by the USB module
// NOTE: Only really required for implementing "tricks" in converters for odd protocols
void scan_finishedWithUSBBuffer( uint8_t sentKeys )
{
        return;
}


inline void capsense_scan()
{
        // Accumulated average used for the next scan
        uint32_t cur_full_avg = 0;
        uint32_t cur_high_avg = 0;

        // Reset average counters
        low_avg = 0;
        low_count = 0;

        high_count = 0;

        // Scan each of the mapped strobes in the matrix
        for ( uint8_t strober = 0; strober < total_strobes; ++strober )
        {
                uint8_t map_strobe = strobe_map[strober];

                uint8_t tries = 1;
                while ( tries++ && sampleColumn( map_strobe ) ) { tries &= 0x7; } // don't waste this one just because the last one was poop.

                // Only process sense data if warmup is finished
                if ( boot_count >= WARMUP_LOOPS )
                {
                        column = testColumn( map_strobe );

                        idle |= column; // if column has any pressed keys, then we are not idle.

                        // TODO Is this needed anymore? Really only helps debug -HaaTa
                        if( column != cur_keymap[map_strobe] && ( boot_count >= WARMUP_LOOPS ) )
                        {
                                cur_keymap[map_strobe] = column;
                                keymap_change = 1;
                        }

                        idle |= keymap_change; // if any keys have changed inc. released, then we are not idle.
                }

                if ( error == 0x50 )
                {
                        error_data |= (((uint16_t)map_strobe) << 12);
                }

                uint8_t strobe_line = map_strobe << MUXES_COUNT_XSHIFT;
                for ( int i = 0; i < MUXES_COUNT; ++i )
                {
                        // discard sketchy low bit, and meaningless high bits.
                        uint8_t sample = samples[i] >> 1;
                        full_samples[strobe_line + i] = sample;
                        keys_averages_acc[strobe_line + i] += sample;
                }

                // Accumulate 3 total averages (used for determining starting average during warmup)
                //     full_avg - Average of all sampled lines on the previous scan set
                // cur_full_avg - Average of all sampled lines for this scan set
                //     high_avg - Average of all sampled lines above full_avg on the previous scan set
                // cur_high_avg - Average of all sampled lines above full_avg
                //      low_avg - Average of all sampled lines below or equal to full_avg
                if ( boot_count < WARMUP_LOOPS )
                {
                        for ( uint8_t i = 0; i < MUXES_COUNT; ++i )
                        {
                                uint8_t sample = samples[i] >> 1;

                                // Sample is high, add it to high avg
                                if ( sample > full_avg )
                                {
                                        high_count++;
                                        cur_high_avg += sample;
                                }
                                // Sample is low, add it to low avg
                                else
                                {
                                        low_count++;
                                        low_avg += sample;
                                }

                                // If sample is higher than previous high_avg, then mark as "problem key"
                                keys_problem[strobe_line + i] = sample > high_avg ? sample : 0;

                                // Prepare for next average
                                cur_full_avg += sample;
                        }
                }
        } // for strober

        // Update total sense average (only during warm-up)
        if ( boot_count < WARMUP_LOOPS )
        {
                full_avg = cur_full_avg / (total_strobes * MUXES_COUNT);
                high_avg = cur_high_avg / high_count;
                low_avg /= low_count;

                // Update the base average value using the low_avg (best chance of not ignoring a keypress)
                for ( int i = 0; i < KEY_COUNT; ++i )
                {
                        keys_averages[i] = low_avg;
                        keys_averages_acc[i] = low_avg;
                }
        }

#ifdef VERIFY_TEST_PAD
        // verify test key is not down.
        if ( ( cur_keymap[TEST_KEY_STROBE] & TEST_KEY_MASK ) )
        {
                error = 0x05;
                error_data = cur_keymap[TEST_KEY_STROBE] << 8;
                error_data += full_samples[TEST_KEY_STROBE * 8];
        }
#endif

        /** aggregate if booting, or if idle;
         * else, if not booting, check for dirty USB.
         * */

        idle_count++;
        idle_count &= IDLE_COUNT_MASK;

        // Warm up voltage references
        if ( boot_count < WARMUP_LOOPS )
        {
                boot_count++;

                switch ( boot_count )
                {
                // First loop
                case 1:
                        // Show msg at first iteration only
                        info_msg("Warming up the voltage references");
                        break;
                // Middle iterations
                case 300:
                case 600:
                case 900:
                case 1200:
                        print(".");
                        break;
                // Last loop
                case WARMUP_STOP:
                        print("\n");
                        info_msg("Warmup finished using ");
                        printInt16( WARMUP_LOOPS );
                        print(" iterations\n");

                        // Display the final calculated averages of all the sensed strobes
                        info_msg("Full average (");
                        printInt8( total_strobes * MUXES_COUNT );
                        print("): ");
                        printHex( full_avg );

                        print("  High average (");
                        printInt8( high_count );
                        print("): ");
                        printHex( high_avg );

                        print("  Low average (");
                        printInt8( low_count );
                        print("): ");
                        printHex( low_avg );
                        print("\n");

                        // Display problem keys, and the sense value at the time
                        for ( uint8_t key = 0; key < KEY_COUNT; key++ )
                        {
                                if ( keys_problem[key] )
                                {
                                        warn_msg("Problem key detected: ");
                                        printHex( key );
                                        print(" (");
                                        printHex( keys_problem[key] );
                                        print(")\n");
                                }
                        }

                        info_print("If problem keys were detected, and were being held down, they will be reset as soon as let go");
                        break;
                }
        }
        else
        {
                // Reset accumulators and idle flag/counter
                if ( keymap_change )
                {
                        for ( uint8_t c = 0; c < KEY_COUNT; ++c ) { keys_averages_acc[c] = 0; }
                        idle_count = 0;
                        idle = 0;

                        keymap_change = 0;
                }

                if ( !idle_count )
                {
                        if( idle )
                        {
                                // aggregate
                                for ( uint8_t i = 0; i < KEY_COUNT; ++i )
                                {
                                        uint16_t acc = keys_averages_acc[i] >> IDLE_COUNT_SHIFT;
                                        uint32_t av = keys_averages[i];

                                        av = (av << KEYS_AVERAGES_MIX_SHIFT) - av + acc;
                                        av >>= KEYS_AVERAGES_MIX_SHIFT;

                                        keys_averages[i] = av;
                                        keys_averages_acc[i] = 0;
                                }
                        }

                        if ( boot_count >= WARMUP_LOOPS )
                        {
                                dump();
                        }
                }

        }
}


void setup_ADC()
{
        // disable adc digital pins.
        DIDR1 |= (1 << AIN0D) | (1<<AIN1D); // set disable on pins 1,0.
        DDRF = 0x0;
        PORTF = 0x0;
        uint8_t mux = 0 & 0x1f; // 0 == first. // 0x1e = 1.1V ref.

        // 0 = external aref 1,1 = 2.56V internal ref
        uint8_t aref = ((1 << REFS1) | (1 << REFS0)) & ((1 << REFS1) | (1 << REFS0));
        uint8_t adate = (1 << ADATE) & (1 << ADATE); // trigger enable
        uint8_t trig = 0 & ((1 << ADTS0) | (1 << ADTS1) | (1 << ADTS2)); // 0 = free running
        // ps2, ps1 := /64 ( 2^6 ) ps2 := /16 (2^4), ps1 := 4, ps0 :=2, PS1,PS0 := 8 (2^8)
        uint8_t prescale = ( ((PRESCALE) << PRESCALE_SHIFT) & PRESCALE_MASK ); // 001 == 2^1 == 2
        uint8_t hispeed = (1 << ADHSM);
        uint8_t en_mux = (1 << ACME);

        ADCSRA = (1 << ADEN) | prescale; // ADC enable

        // select ref.
        //ADMUX |= ((1 << REFS1) | (1 << REFS0)); // 2.56 V internal.
        //ADMUX |= ((1 << REFS0) ); // Vcc with external cap.
        //ADMUX &= ~((1 << REFS1) | (1 << REFS0)); // 0,0 : aref.
        ADMUX = aref | mux | ADLAR_BITS;

        // set free-running
        ADCSRA |= adate; // trigger enable
        ADCSRB  = en_mux | hispeed | trig | (ADCSRB & ~((1 << ADTS0) | (1 << ADTS1) | (1 << ADTS2))); // trigger select free running

        ADCSRA |= (1 << ADEN); // ADC enable
        ADCSRA |= (1 << ADSC); // start conversions q
}


void recovery( uint8_t on )
{
        DDRB  |=  (1 << RECOVERY_CONTROL);
        PORTB &= ~(1 << RECOVERY_SINK);   // SINK always zero
        DDRB  &= ~(1 << RECOVERY_SOURCE); // SOURCE high imp

        if ( on )
        {
                // set strobes to sink to gnd.
                DDRC |= C_MASK;
                DDRD |= D_MASK;
                DDRE |= E_MASK;

                PORTC &= ~C_MASK;
                PORTD &= ~D_MASK;
                PORTE &= ~E_MASK;

                DDRB  |= (1 << RECOVERY_SINK);   // SINK pull
                PORTB |= (1 << RECOVERY_CONTROL);
                PORTB |= (1 << RECOVERY_SOURCE); // SOURCE high
                DDRB  |= (1 << RECOVERY_SOURCE);
        }
        else
        {
                PORTB &= ~(1 << RECOVERY_CONTROL);
                DDRB  &= ~(1 << RECOVERY_SOURCE);
                PORTB &= ~(1 << RECOVERY_SOURCE); // SOURCE low
                DDRB  &= ~(1 << RECOVERY_SINK);   // SINK high-imp
        }
}


void hold_sample( uint8_t on )
{
        if ( !on )
        {
                PORTB |= (1 << SAMPLE_CONTROL);
                DDRB  |= (1 << SAMPLE_CONTROL);
        }
        else
        {
                DDRB  |=  (1 << SAMPLE_CONTROL);
                PORTB &= ~(1 << SAMPLE_CONTROL);
        }
}


void strobe_w( uint8_t strobe_num )
{
        PORTC &= ~(C_MASK);
        PORTD &= ~(D_MASK);
        PORTE &= ~(E_MASK);

        // Strobe table
        // Not all strobes are used depending on which are detected
        switch ( strobe_num )
        {

        case 0:  PORTD |= (1 << 0); break;
        case 1:  PORTD |= (1 << 1); break;
        case 2:  PORTD |= (1 << 2); break;
        case 3:  PORTD |= (1 << 3); break;
        case 4:  PORTD |= (1 << 4); break;
        case 5:  PORTD |= (1 << 5); break;
        case 6:  PORTD |= (1 << 6); break;
        case 7:  PORTD |= (1 << 7); break;

        case 8:  PORTE |= (1 << 0); break;
        case 9:  PORTE |= (1 << 1); break;

        case 10: PORTC |= (1 << 0); break;
        case 11: PORTC |= (1 << 1); break;
        case 12: PORTC |= (1 << 2); break;
        case 13: PORTC |= (1 << 3); break;
        case 14: PORTC |= (1 << 4); break;
        case 15: PORTC |= (1 << 5); break;
        case 16: PORTC |= (1 << 6); break;
        case 17: PORTC |= (1 << 7); break;

        default:
                break;
        }
}


inline uint16_t getADC(void)
{
        ADCSRA |= (1 << ADIF); // clear int flag by writing 1.

        //wait for last read to complete.
        while ( !( ADCSRA & (1 << ADIF) ) );

        return ADC; // return sample
}


int sampleColumn_8x( uint8_t column, uint16_t * buffer )
{
        // ensure all probe lines are driven low, and chill for recovery delay.
        ADCSRA |= (1 << ADEN) | (1 << ADSC); // enable and start conversions

        PORTC &= ~C_MASK;
        PORTD &= ~D_MASK;
        PORTE &= ~E_MASK;

        PORTF = 0;
        DDRF  = 0;

        recovery( OFF );
        strobe_w( column );

        hold_sample( OFF );
        SET_FULL_MUX( 0 );

        // Allow strobes to settle
        for ( uint8_t i = 0; i < STROBE_SETTLE; ++i ) { getADC(); }

        hold_sample( ON );

        uint8_t mux = 0;
        SET_FULL_MUX( mux );
        getADC(); // throw away; unknown mux.
        do {
                SET_FULL_MUX( mux + 1 ); // our *next* sample will use this

                // retrieve current read.
                buffer[mux] = getADC();
                mux++;

        } while ( mux < 8 );

        hold_sample( OFF );
        recovery( ON );

        // turn off adc.
        ADCSRA &= ~(1 << ADEN);

        // pull all columns' strobe-lines low.
        DDRC |= C_MASK;
        DDRD |= D_MASK;
        DDRE |= E_MASK;

        PORTC &= ~C_MASK;
        PORTD &= ~D_MASK;
        PORTE &= ~E_MASK;

        return 0;
}


int sampleColumn( uint8_t column )
{
        int rval = 0;

        rval = sampleColumn_8x( column, samples );

        return rval;
}


uint8_t testColumn( uint8_t strobe )
{
        uint16_t db_delta = 0;
        uint8_t  db_sample = 0;
        uint16_t db_threshold = 0;

        uint8_t column = 0;
        uint8_t bit = 1;

        for ( uint8_t mux = 0; mux < MUXES_COUNT; ++mux )
        {
                uint16_t delta = keys_averages[(strobe << MUXES_COUNT_XSHIFT) + mux];

                uint8_t key = (strobe << MUXES_COUNT_XSHIFT) + mux;

                // Check if this is a bad key (e.g. test point, or non-existent key)
                if ( keys_problem[key] )
                {
                        // If the sample value of the problem key goes below full_avg (overall initial average)
                        //  re-enable the key
                        if ( (db_sample = samples[mux] >> 1) < full_avg )
                        {
                                info_msg("Re-enabling problem key: ");
                                printHex( key );
                                print("\n");

                                keys_problem[key] = 0;
                        }
                        // Otherwise, don't waste any more cycles processing the problem key
                        else
                        {
                                continue;
                        }
                }

                // Keypress detected
                //  db_sample (uint8_t), discard meaningless high bit, and garbage low bit
                if ( (db_sample = samples[mux] >> 1) > (db_threshold = threshold) + (db_delta = delta) )
                {
                        column |= bit;

                        // Only register keypresses once the warmup is complete, or not enough debounce info
                        if ( keys_debounce[key] <= DEBOUNCE_THRESHOLD )
                        {
                                // Add to the Macro processing buffer if debounce criteria met
                                // Automatically handles converting to a USB code and sending off to the PC
                                if ( keys_debounce[key] == DEBOUNCE_THRESHOLD )
                                {
//#define KEYSCAN_DEBOUNCE_DEBUG
#ifdef KEYSCAN_DEBOUNCE_DEBUG
                                        // Debug message
                                        print("0x");
                                        printHex_op( key, 2 );
                                        print(" ");
#endif

                                        // Only add the key to the buffer once
                                        // NOTE: Buffer can easily handle multiple adds, just more efficient
                                        //        and nicer debug messages :P
                                        //bufferAdd( key );
                                }

                                keys_debounce[key]++;

#define KEYSCAN_THRESHOLD_DEBUG
#ifdef KEYSCAN_THRESHOLD_DEBUG
                                // Debug message
                                // <key> [<strobe>:<mux>] : <sense val> : <delta + threshold> : <margin>
                                dbug_msg("0x");
                                printHex_op( key, 2 );
                                print(" [");
                                printInt8( strobe );
                                print(":");
                                printInt8( mux );
                                print("] : ");
                                printHex( db_sample ); // Sense
                                print(" : ");
                                printHex( db_threshold );
                                print("+");
                                printHex( db_delta );
                                print("=");
                                printHex( db_threshold + db_delta ); // Sense compare
                                print(" : ");
                                printHex( db_sample - ( db_threshold + db_delta ) ); // Margin
                                print("\n");
#endif
                        }
                }
                // Clear debounce entry if no keypress detected
                else
                {
                        // If the key was previously pressed, remove from the buffer
                        for ( uint8_t c = 0; c < KeyIndex_BufferUsed; c++ )
                        {
                                // Key to release found
                                if ( KeyIndex_Buffer[c] == key )
                                {
                                        // Shift keys from c position
                                        for ( uint8_t k = c; k < KeyIndex_BufferUsed - 1; k++ )
                                                KeyIndex_Buffer[k] = KeyIndex_Buffer[k + 1];

                                        // Decrement Buffer
                                        KeyIndex_BufferUsed--;

                                        break;
                                }
                        }


                        // Clear debounce entry
                        keys_debounce[key] = 0;
                }

                bit <<= 1;
        }
        return column;
}


void dump(void) {

#ifdef DEBUG_FULL_SAMPLES_AVERAGES
        // we don't want to debug-out during the measurements.
        if ( !dump_count )
        {
                // Averages currently set per key
                for ( int i = 0; i < KEY_COUNT; ++i )
                {
                        if ( !(i & 0x0f) )
                        {
                                print("\n");
                        }
                        else if ( !(i & 0x07) )
                        {
                                print("  ");
                        }

                        print(" ");
                        printHex( keys_averages[i] );
                }

                print("\n");

                // Previously read full ADC scans?
                for ( int i = 0; i< KEY_COUNT; ++i)
                {
                        if ( !(i & 0x0f) )
                        {
                                print("\n");
                        }
                        else if ( !(i & 0x07) )
                        {
                                print("  ");
                        }

                        print(" ");
                        printHex(full_samples[i]);
                }
        }
#endif

#ifdef DEBUG_STROBE_SAMPLES_AVERAGES
        // Per strobe information
        uint8_t cur_strober = ze_strober;
        print("\n");

        printHex(cur_strober);

        // Previously read ADC scans on current strobe
        print(" :");
        for ( uint8_t i = 0; i < MUXES_COUNT; ++i )
        {
                print(" ");
                printHex(full_samples[(cur_strober << MUXES_COUNT_XSHIFT) + i]);
        }

        // Averages current set on current strobe
        print(" :");

        for ( uint8_t i = 0; i < MUXES_COUNT; ++i )
        {
                print(" ");
                printHex(keys_averages[(cur_strober << MUXES_COUNT_XSHIFT) + i]);
        }

#endif

#ifdef DEBUG_USB_KEYMAP
        print("\n      ");

        // Current keymap values
        for ( uint8_t i = 0; i < total_strobes; ++i )
        {
                printHex(cur_keymap[i]);
                print(" ");
        }
#endif

        ze_strober++;
        ze_strober &= 0xf;

        dump_count++;
        dump_count &= 0x0f;
}