Ternary Chord Keyboard

Accukey lives!

Jan 7, 2018

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5 respects

usb

retro

keyboard

Components and supplies

6 mm push-button switch

.1 inch header socket (17 way)

5 volt LED

USB cable (Micro B)

Arduino Micro

Apps and platforms

Arduino IDE

Project description

Code

The software

c_cpp

1#include <Keyboard.h>
2//
3//left buttons
4#define button_1 5
5#define   button_2 6
6#define button_3 7
7#define button_4 8
8#define button_9  SCK
9#define   button_10 MISO
10#define button_11 A5
11#define button_12 A4
12
13//right buttons
14#define   button_5 9
15#define button_6 10
16#define button_7 11
17#define button_8 12//A1
18#define   button_13 A3
19#define button_14 A2
20#define button_15 A1//12
21#define button_16   A0
22
23#define caps_lock_led MOSI
24#define ctrl_led  1
25//alt has not been   coded into table 
26#define alt_led  0
27//On my original pcb I wired fn_led to   pin TX, which I couldn't get to work
28#define fn_led 4 
29
30
31//from patent   4,775,225 (modified)-
32//Notes: 
33//Patent table 3, which I used to create the   table below, lists g twice and ommits 6
34//Patent tables 1 & 2 list 6 as occuring   at 0001 0010 (sw4_t and sw7_t), the other g is in its correct place
35//Placement   of ! and ? is transposed in table 3 compared to tables 1 and 2 - I chose to follow   table 3
36//Tables 1 and 2 list both numbers 3 and 5 as code 2000 0001 - where   2 means switch pressed away from you and 1 is switch toward you
37//From table   3
38//3 is code 2000 0001
39//5 is code 2000 0002
40//I have redesignated uppercase(UC)   and lowercase(LC)
41//code 0010 2000 used for shift
42//code 0020 1000 used for   caps lock
43//
44//Warning on char codes
45//Characters are sent as if from a   US keyboard
46//Characters change if receiving computer is not set up for US keyboard
47//Example:
48//In   my case:
49//@ becomes "
50//" becomes @
51//# becomes 
52//See:
53//https://forum.arduino.cc/index.php?topic=428331.0
54//Retrieved   28/Dec/2017
55
56const unsigned char key_table[8][8]{'j','m','y','0','(','+','2','4',
57                                     'k','p','z','1',')','"','3','5',
58                                    ',',';','$','@','\	',194,'\\'','%',//F1   escape(\\) required to allow character ' in table  
59                                    '.',':','#','*',128,195,'=','\\b',//CT   F2 
60                                    'u',129,'o','n','-','?','q','w',//LC   as shift
61                                    193,'\
62','i','s','!','/','v','x',//UC   as caps lock
63                                    ' ','t','h','d','6','8','b','f',
64                                     'e','a','r','l','7','9','c','g'};
65//end -   from patent 4,775,225 (modified)
66
67//required to debounce switch
68#define   MAX_CHECKS 10
69//for right hand
70volatile uint8_t Debounced_State=0;//accessed   by isr and main loop code
71uint8_t State[MAX_CHECKS]={0};
72uint8_t Index=0;
73
74//for   left hand
75volatile uint8_t left_Debounced_State=0;//accessed by isr and main   loop code
76uint8_t left_State[MAX_CHECKS]={0};
77uint8_t left_Index=0;
78
79//   the setup function runs once when you press reset or power the board
80void setup()   {
81
82          pinMode(button_1,INPUT_PULLUP);
83          pinMode(button_2,INPUT_PULLUP);
84           pinMode(button_3,INPUT_PULLUP);
85          pinMode(button_4,INPUT_PULLUP);
86           pinMode(button_5,INPUT_PULLUP);
87          pinMode(button_6,INPUT_PULLUP);
88           pinMode(button_7,INPUT_PULLUP);
89          pinMode(button_8,INPUT_PULLUP);
90           
91          pinMode(button_9,INPUT_PULLUP);
92          pinMode(button_10,INPUT_PULLUP);
93           pinMode(button_11,INPUT_PULLUP);
94          pinMode(button_12,INPUT_PULLUP);
95           pinMode(button_13,INPUT_PULLUP);
96          pinMode(button_14,INPUT_PULLUP);
97           pinMode(button_15,INPUT_PULLUP);
98          pinMode(button_16,INPUT_PULLUP);
99
100//led   setup
101          pinMode(caps_lock_led,OUTPUT);
102          pinMode(ctrl_led,OUTPUT);
103           pinMode(alt_led,OUTPUT);
104          pinMode(fn_led,OUTPUT);
105
106//test   led's
107          digitalWrite(caps_lock_led,HIGH);
108          digitalWrite(ctrl_led,HIGH);
109           digitalWrite(alt_led,HIGH);
110          digitalWrite(fn_led,HIGH);
111           delay(1000);
112          digitalWrite(caps_lock_led,LOW);
113          digitalWrite(ctrl_led,LOW);
114           digitalWrite(alt_led,LOW);
115          digitalWrite(fn_led,LOW);          
116
117     // initialize timer1 
118  noInterrupts();           // disable all interrupts
119   TCCR1A = 0;
120  TCCR1B = 0;
121  TCNT1  = 0;
122
123  OCR1A = 625;              //   compare match register  16MHX/256/100HZ 
124  TCCR1B |= (1 << WGM12);   // CTC mode
125   TCCR1B |= (1 << CS12);    // 256 prescaler 
126  TIMSK1 |= (1 << OCIE1A);  //   enable timer compare interrupt
127  interrupts();             // enable all interrupts
128
129
130//   initialize control over the keyboard:
131Keyboard.begin();
132  
133}
134
135//   the loop function runs over and over again forever
136void loop() {
137
138static   bool do_character=false;
139static bool button_up=false;
140static bool chord_ready=false;
141static   bool ctrl_key=false;
142static bool caps_lock_key=false;
143static bool shift_key=false;
144static   bool alt_key=false;
145int DOWN=0;
146int ACROSS=0;
147
148static int RHAND=0;
149static   int LHAND=0;
150
151    noInterrupts();           // disable all interrupts
152if   (Debounced_State && left_Debounced_State){RHAND=Debounced_State;LHAND=left_Debounced_State;chord_ready=true;}//store   chord and flag as ready
153if (!Debounced_State || !left_Debounced_State){if(chord_ready){button_up=true;}}     
154    interrupts();             // enable all interrupts
155
156
157
158if(button_up   && chord_ready)
159{
160chord_ready=false;
161button_up=false;
162do_character=true;
163
164//from   patent 4,775,225 (modified)  
165//'BYTES FROM "DEVICE"
166//The original binary   values have been inverted
167   if (RHAND==128){DOWN=0;}
168   if (RHAND==64){DOWN=1;}
169    if (RHAND==32){DOWN=2;}                  //CONVERT BYTE VALUE TO INDEX
170   if   (RHAND==16){DOWN=3;}                  //VALUE FOR LEFT HAND
171   if (RHAND==8){DOWN=4;}
172    if (RHAND==4){DOWN=5;}
173   if (RHAND==2){DOWN=6;}
174   if (RHAND==1){DOWN=7;}
175    if (LHAND==128){ACROSS=0;}
176   if (LHAND==64){ACROSS=1;}
177   if (LHAND==32){ACROSS=2;}
178    if (LHAND==16){ACROSS=3;}                  //CONVERT BYTE VALUE TO INDEX
179    if (LHAND==8){ACROSS=4;}                  //VALUE FOR RIGHT HAND
180   if (LHAND==4){ACROSS=5;}    
181   if (LHAND==2){ACROSS=6;}
182   if (LHAND==1){ACROSS=7;}
183//READ CHARACTER   FROM TABLE
184//end - from patent 4,775,225 (modified)
185//NOTE DOWN & ACROSS have   default values of zero if no match
186//Example press 2 right hand keys(DOWN) and   s4_a(ACROSS) gives letter m(DOWN=0;ACROSS=1)
187}
188
189if (do_character) 
190{
191   do_character=false;
192
193  switch (key_table[ACROSS][DOWN]){
194    
195    //control   key
196    case 128: ctrl_key=true;digitalWrite(ctrl_led,HIGH);break;
197
198    //caps   lock key
199    case 193:caps_lock_key=!caps_lock_key;
200              if(caps_lock_key){digitalWrite(caps_lock_led,HIGH);}
201                   else{digitalWrite(caps_lock_led,LOW);}break;//toggle caps lock   key
202
203    //shift key              
204    case 129:shift_key=true;digitalWrite(caps_lock_led,HIGH);break;               
205                  
206    default : if(!ctrl_key && !caps_lock_key   && !shift_key){Keyboard.write((unsigned char)key_table[ACROSS][DOWN]);}
207    
208               if(ctrl_key)//control key only
209              {Keyboard.press(128);//control   on
210               Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
211                Keyboard.releaseAll();//control off
212               ctrl_key=false;
213                digitalWrite(ctrl_led,LOW);} 
214                        
215              if(shift_key   && !caps_lock_key)//shift only
216              {Keyboard.press(129);//shift on
217                Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
218               Keyboard.releaseAll();//shift   off
219               shift_key=false;
220               digitalWrite(caps_lock_led,LOW);}
221                  
222              if(caps_lock_key && !shift_key)//caps lock only
223               {
224               if (isAlpha((unsigned char)key_table[ACROSS][DOWN]))
225                {
226                Keyboard.press(129);
227                Keyboard.press((unsigned   char)key_table[ACROSS][DOWN]);
228                Keyboard.releaseAll();
229                }
230                else
231               {
232                Keyboard.press((unsigned   char)key_table[ACROSS][DOWN]);
233                Keyboard.releaseAll();
234                }
235                 } 
236                                                            
237               if(shift_key && caps_lock_key)//shift and caps lock
238              {   if (isAlpha((unsigned char)key_table[ACROSS][DOWN]))
239                {
240                Keyboard.press((unsigned   char)key_table[ACROSS][DOWN]);
241                Keyboard.releaseAll();
242                shift_key=false;
243                 }
244              else
245                {
246                Keyboard.press(129);//shift   on
247                Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
248                 Keyboard.releaseAll();//shift off
249                shift_key=false;
250                 }
251                }break;
252                                      
253     }
254
255}
256
257
258}
259
260
261//my_functions
262ISR(TIMER1_COMPA_vect)           // timer compare interrupt service routine
263{
264//
265//read buttons
266   uint8_t temp=0x00;
267  uint8_t left_temp=0x00;
268  
269  left_temp|=!digitalRead(button_1)<<6;left_temp|=!digitalRead(button_9)<<7;
270   left_temp|=!digitalRead(button_2)<<4;left_temp|=!digitalRead(button_10)<<5;
271   left_temp|=!digitalRead(button_3)<<2;left_temp|=!digitalRead(button_11)<<3;
272   left_temp|=!digitalRead(button_4)<<0;left_temp|=!digitalRead(button_12)<<1;
273   
274  temp|=!digitalRead(button_5)<<6;temp|=!digitalRead(button_13)<<7;
275  temp|=!digitalRead(button_6)<<4;temp|=!digitalRead(button_14)<<5;
276   temp|=!digitalRead(button_7)<<2;temp|=!digitalRead(button_15)<<3;
277  temp|=!digitalRead(button_8)<<0;temp|=!digitalRead(button_16)<<1;
278             
279//debounce
280  uint8_t i,j;
281
282//for right hand
283  State[Index]=   temp;
284  ++Index;
285  j=0xFF;
286  for (i=0;i<MAX_CHECKS;i++){j=j&State[i];}
287   Debounced_State=j;
288  if(Index>=MAX_CHECKS){Index=0;} 
289
290//for left hand   left_
291  left_State[left_Index]= left_temp;
292  ++left_Index;
293  j=0xFF;
294   for (i=0;i<MAX_CHECKS;i++){j=j&left_State[i];}
295  left_Debounced_State=j;
296   if(left_Index>=MAX_CHECKS){left_Index=0;}
297}
298//-----------end------------   
299

#include <Keyboard.h>
//
//left buttons
#define button_1 5
#define   button_2 6
#define button_3 7
#define button_4 8
#define button_9  SCK
#define   button_10 MISO
#define button_11 A5
#define button_12 A4

//right buttons
#define   button_5 9
#define button_6 10
#define button_7 11
#define button_8 12//A1
#define   button_13 A3
#define button_14 A2
#define button_15 A1//12
#define button_16   A0

#define caps_lock_led MOSI
#define ctrl_led  1
//alt has not been   coded into table 
#define alt_led  0
//On my original pcb I wired fn_led to   pin TX, which I couldn't get to work
#define fn_led 4 


//from patent   4,775,225 (modified)-
//Notes: 
//Patent table 3, which I used to create the   table below, lists g twice and ommits 6
//Patent tables 1 & 2 list 6 as occuring   at 0001 0010 (sw4_t and sw7_t), the other g is in its correct place
//Placement   of ! and ? is transposed in table 3 compared to tables 1 and 2 - I chose to follow   table 3
//Tables 1 and 2 list both numbers 3 and 5 as code 2000 0001 - where   2 means switch pressed away from you and 1 is switch toward you
//From table   3
//3 is code 2000 0001
//5 is code 2000 0002
//I have redesignated uppercase(UC)   and lowercase(LC)
//code 0010 2000 used for shift
//code 0020 1000 used for   caps lock
//
//Warning on char codes
//Characters are sent as if from a   US keyboard
//Characters change if receiving computer is not set up for US keyboard
//Example:
//In   my case:
//@ becomes "
//" becomes @
//# becomes 
//See:
//https://forum.arduino.cc/index.php?topic=428331.0
//Retrieved   28/Dec/2017

const unsigned char key_table[8][8]{'j','m','y','0','(','+','2','4',
                                     'k','p','z','1',')','"','3','5',
                                    ',',';','$','@','\	',194,'\\'','%',//F1   escape(\\) required to allow character ' in table  
                                    '.',':','#','*',128,195,'=','\\b',//CT   F2 
                                    'u',129,'o','n','-','?','q','w',//LC   as shift
                                    193,'\
','i','s','!','/','v','x',//UC   as caps lock
                                    ' ','t','h','d','6','8','b','f',
                                     'e','a','r','l','7','9','c','g'};
//end -   from patent 4,775,225 (modified)

//required to debounce switch
#define   MAX_CHECKS 10
//for right hand
volatile uint8_t Debounced_State=0;//accessed   by isr and main loop code
uint8_t State[MAX_CHECKS]={0};
uint8_t Index=0;

//for   left hand
volatile uint8_t left_Debounced_State=0;//accessed by isr and main   loop code
uint8_t left_State[MAX_CHECKS]={0};
uint8_t left_Index=0;

//   the setup function runs once when you press reset or power the board
void setup()   {

          pinMode(button_1,INPUT_PULLUP);
          pinMode(button_2,INPUT_PULLUP);
           pinMode(button_3,INPUT_PULLUP);
          pinMode(button_4,INPUT_PULLUP);
           pinMode(button_5,INPUT_PULLUP);
          pinMode(button_6,INPUT_PULLUP);
           pinMode(button_7,INPUT_PULLUP);
          pinMode(button_8,INPUT_PULLUP);
           
          pinMode(button_9,INPUT_PULLUP);
          pinMode(button_10,INPUT_PULLUP);
           pinMode(button_11,INPUT_PULLUP);
          pinMode(button_12,INPUT_PULLUP);
           pinMode(button_13,INPUT_PULLUP);
          pinMode(button_14,INPUT_PULLUP);
           pinMode(button_15,INPUT_PULLUP);
          pinMode(button_16,INPUT_PULLUP);

//led   setup
          pinMode(caps_lock_led,OUTPUT);
          pinMode(ctrl_led,OUTPUT);
           pinMode(alt_led,OUTPUT);
          pinMode(fn_led,OUTPUT);

//test   led's
          digitalWrite(caps_lock_led,HIGH);
          digitalWrite(ctrl_led,HIGH);
           digitalWrite(alt_led,HIGH);
          digitalWrite(fn_led,HIGH);
           delay(1000);
          digitalWrite(caps_lock_led,LOW);
          digitalWrite(ctrl_led,LOW);
           digitalWrite(alt_led,LOW);
          digitalWrite(fn_led,LOW);          

     // initialize timer1 
  noInterrupts();           // disable all interrupts
   TCCR1A = 0;
  TCCR1B = 0;
  TCNT1  = 0;

  OCR1A = 625;              //   compare match register  16MHX/256/100HZ 
  TCCR1B |= (1 << WGM12);   // CTC mode
   TCCR1B |= (1 << CS12);    // 256 prescaler 
  TIMSK1 |= (1 << OCIE1A);  //   enable timer compare interrupt
  interrupts();             // enable all interrupts


//   initialize control over the keyboard:
Keyboard.begin();
  
}

//   the loop function runs over and over again forever
void loop() {

static   bool do_character=false;
static bool button_up=false;
static bool chord_ready=false;
static   bool ctrl_key=false;
static bool caps_lock_key=false;
static bool shift_key=false;
static   bool alt_key=false;
int DOWN=0;
int ACROSS=0;

static int RHAND=0;
static   int LHAND=0;

    noInterrupts();           // disable all interrupts
if   (Debounced_State && left_Debounced_State){RHAND=Debounced_State;LHAND=left_Debounced_State;chord_ready=true;}//store   chord and flag as ready
if (!Debounced_State || !left_Debounced_State){if(chord_ready){button_up=true;}}     
    interrupts();             // enable all interrupts



if(button_up   && chord_ready)
{
chord_ready=false;
button_up=false;
do_character=true;

//from   patent 4,775,225 (modified)  
//'BYTES FROM "DEVICE"
//The original binary   values have been inverted
   if (RHAND==128){DOWN=0;}
   if (RHAND==64){DOWN=1;}
    if (RHAND==32){DOWN=2;}                  //CONVERT BYTE VALUE TO INDEX
   if   (RHAND==16){DOWN=3;}                  //VALUE FOR LEFT HAND
   if (RHAND==8){DOWN=4;}
    if (RHAND==4){DOWN=5;}
   if (RHAND==2){DOWN=6;}
   if (RHAND==1){DOWN=7;}
    if (LHAND==128){ACROSS=0;}
   if (LHAND==64){ACROSS=1;}
   if (LHAND==32){ACROSS=2;}
    if (LHAND==16){ACROSS=3;}                  //CONVERT BYTE VALUE TO INDEX
    if (LHAND==8){ACROSS=4;}                  //VALUE FOR RIGHT HAND
   if (LHAND==4){ACROSS=5;}    
   if (LHAND==2){ACROSS=6;}
   if (LHAND==1){ACROSS=7;}
//READ CHARACTER   FROM TABLE
//end - from patent 4,775,225 (modified)
//NOTE DOWN & ACROSS have   default values of zero if no match
//Example press 2 right hand keys(DOWN) and   s4_a(ACROSS) gives letter m(DOWN=0;ACROSS=1)
}

if (do_character) 
{
   do_character=false;

  switch (key_table[ACROSS][DOWN]){
    
    //control   key
    case 128: ctrl_key=true;digitalWrite(ctrl_led,HIGH);break;

    //caps   lock key
    case 193:caps_lock_key=!caps_lock_key;
              if(caps_lock_key){digitalWrite(caps_lock_led,HIGH);}
                   else{digitalWrite(caps_lock_led,LOW);}break;//toggle caps lock   key

    //shift key              
    case 129:shift_key=true;digitalWrite(caps_lock_led,HIGH);break;               
                  
    default : if(!ctrl_key && !caps_lock_key   && !shift_key){Keyboard.write((unsigned char)key_table[ACROSS][DOWN]);}
    
               if(ctrl_key)//control key only
              {Keyboard.press(128);//control   on
               Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
                Keyboard.releaseAll();//control off
               ctrl_key=false;
                digitalWrite(ctrl_led,LOW);} 
                        
              if(shift_key   && !caps_lock_key)//shift only
              {Keyboard.press(129);//shift on
                Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
               Keyboard.releaseAll();//shift   off
               shift_key=false;
               digitalWrite(caps_lock_led,LOW);}
                  
              if(caps_lock_key && !shift_key)//caps lock only
               {
               if (isAlpha((unsigned char)key_table[ACROSS][DOWN]))
                {
                Keyboard.press(129);
                Keyboard.press((unsigned   char)key_table[ACROSS][DOWN]);
                Keyboard.releaseAll();
                }
                else
               {
                Keyboard.press((unsigned   char)key_table[ACROSS][DOWN]);
                Keyboard.releaseAll();
                }
                 } 
                                                            
               if(shift_key && caps_lock_key)//shift and caps lock
              {   if (isAlpha((unsigned char)key_table[ACROSS][DOWN]))
                {
                Keyboard.press((unsigned   char)key_table[ACROSS][DOWN]);
                Keyboard.releaseAll();
                shift_key=false;
                 }
              else
                {
                Keyboard.press(129);//shift   on
                Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
                 Keyboard.releaseAll();//shift off
                shift_key=false;
                 }
                }break;
                                      
     }

}


}


//my_functions
ISR(TIMER1_COMPA_vect)           // timer compare interrupt service routine
{
//
//read buttons
   uint8_t temp=0x00;
  uint8_t left_temp=0x00;
  
  left_temp|=!digitalRead(button_1)<<6;left_temp|=!digitalRead(button_9)<<7;
   left_temp|=!digitalRead(button_2)<<4;left_temp|=!digitalRead(button_10)<<5;
   left_temp|=!digitalRead(button_3)<<2;left_temp|=!digitalRead(button_11)<<3;
   left_temp|=!digitalRead(button_4)<<0;left_temp|=!digitalRead(button_12)<<1;
   
  temp|=!digitalRead(button_5)<<6;temp|=!digitalRead(button_13)<<7;
  temp|=!digitalRead(button_6)<<4;temp|=!digitalRead(button_14)<<5;
   temp|=!digitalRead(button_7)<<2;temp|=!digitalRead(button_15)<<3;
  temp|=!digitalRead(button_8)<<0;temp|=!digitalRead(button_16)<<1;
             
//debounce
  uint8_t i,j;

//for right hand
  State[Index]=   temp;
  ++Index;
  j=0xFF;
  for (i=0;i<MAX_CHECKS;i++){j=j&State[i];}
   Debounced_State=j;
  if(Index>=MAX_CHECKS){Index=0;} 

//for left hand   left_
  left_State[left_Index]= left_temp;
  ++left_Index;
  j=0xFF;
   for (i=0;i<MAX_CHECKS;i++){j=j&left_State[i];}
  left_Debounced_State=j;
   if(left_Index>=MAX_CHECKS){left_Index=0;}
}
//-----------end------------

The software

c_cpp

1#include <Keyboard.h>
2//
3//left buttons
4#define button_1 5
5#define  button_2 6
6#define button_3 7
7#define button_4 8
8#define button_9  SCK
9#define  button_10 MISO
10#define button_11 A5
11#define button_12 A4
12
13//right buttons
14#define  button_5 9
15#define button_6 10
16#define button_7 11
17#define button_8 12//A1
18#define  button_13 A3
19#define button_14 A2
20#define button_15 A1//12
21#define button_16  A0
22
23#define caps_lock_led MOSI
24#define ctrl_led  1
25//alt has not been  coded into table 
26#define alt_led  0
27//On my original pcb I wired fn_led to  pin TX, which I couldn't get to work
28#define fn_led 4 
29
30
31//from patent  4,775,225 (modified)-
32//Notes: 
33//Patent table 3, which I used to create the  table below, lists g twice and ommits 6
34//Patent tables 1 & 2 list 6 as occuring  at 0001 0010 (sw4_t and sw7_t), the other g is in its correct place
35//Placement  of ! and ? is transposed in table 3 compared to tables 1 and 2 - I chose to follow  table 3
36//Tables 1 and 2 list both numbers 3 and 5 as code 2000 0001 - where  2 means switch pressed away from you and 1 is switch toward you
37//From table  3
38//3 is code 2000 0001
39//5 is code 2000 0002
40//I have redesignated uppercase(UC)  and lowercase(LC)
41//code 0010 2000 used for shift
42//code 0020 1000 used for  caps lock
43//
44//Warning on char codes
45//Characters are sent as if from a  US keyboard
46//Characters change if receiving computer is not set up for US keyboard
47//Example:
48//In  my case:
49//@ becomes "
50//" becomes @
51//# becomes 
52//See:
53//https://forum.arduino.cc/index.php?topic=428331.0
54//Retrieved  28/Dec/2017
55
56const unsigned char key_table[8][8]{'j','m','y','0','(','+','2','4',
57                                    'k','p','z','1',')','"','3','5',
58                                    ',',';','$','@','\	',194,'\\'','%',//F1  escape(\\) required to allow character ' in table  
59                                    '.',':','#','*',128,195,'=','\\b',//CT  F2 
60                                    'u',129,'o','n','-','?','q','w',//LC  as shift
61                                    193,'\n','i','s','!','/','v','x',//UC  as caps lock
62                                    ' ','t','h','d','6','8','b','f',
63                                    'e','a','r','l','7','9','c','g'};
64//end -  from patent 4,775,225 (modified)
65
66//required to debounce switch
67#define  MAX_CHECKS 10
68//for right hand
69volatile uint8_t Debounced_State=0;//accessed  by isr and main loop code
70uint8_t State[MAX_CHECKS]={0};
71uint8_t Index=0;
72
73//for  left hand
74volatile uint8_t left_Debounced_State=0;//accessed by isr and main  loop code
75uint8_t left_State[MAX_CHECKS]={0};
76uint8_t left_Index=0;
77
78//  the setup function runs once when you press reset or power the board
79void setup()  {
80
81          pinMode(button_1,INPUT_PULLUP);
82          pinMode(button_2,INPUT_PULLUP);
83          pinMode(button_3,INPUT_PULLUP);
84          pinMode(button_4,INPUT_PULLUP);
85          pinMode(button_5,INPUT_PULLUP);
86          pinMode(button_6,INPUT_PULLUP);
87          pinMode(button_7,INPUT_PULLUP);
88          pinMode(button_8,INPUT_PULLUP);
89          
90          pinMode(button_9,INPUT_PULLUP);
91          pinMode(button_10,INPUT_PULLUP);
92          pinMode(button_11,INPUT_PULLUP);
93          pinMode(button_12,INPUT_PULLUP);
94          pinMode(button_13,INPUT_PULLUP);
95          pinMode(button_14,INPUT_PULLUP);
96          pinMode(button_15,INPUT_PULLUP);
97          pinMode(button_16,INPUT_PULLUP);
98
99//led  setup
100          pinMode(caps_lock_led,OUTPUT);
101          pinMode(ctrl_led,OUTPUT);
102          pinMode(alt_led,OUTPUT);
103          pinMode(fn_led,OUTPUT);
104
105//test  led's
106          digitalWrite(caps_lock_led,HIGH);
107          digitalWrite(ctrl_led,HIGH);
108          digitalWrite(alt_led,HIGH);
109          digitalWrite(fn_led,HIGH);
110          delay(1000);
111          digitalWrite(caps_lock_led,LOW);
112          digitalWrite(ctrl_led,LOW);
113          digitalWrite(alt_led,LOW);
114          digitalWrite(fn_led,LOW);          
115
116    // initialize timer1 
117  noInterrupts();           // disable all interrupts
118  TCCR1A = 0;
119  TCCR1B = 0;
120  TCNT1  = 0;
121
122  OCR1A = 625;              //  compare match register  16MHX/256/100HZ 
123  TCCR1B |= (1 << WGM12);   // CTC mode
124  TCCR1B |= (1 << CS12);    // 256 prescaler 
125  TIMSK1 |= (1 << OCIE1A);  //  enable timer compare interrupt
126  interrupts();             // enable all interrupts
127
128
129//  initialize control over the keyboard:
130Keyboard.begin();
131  
132}
133
134//  the loop function runs over and over again forever
135void loop() {
136
137static  bool do_character=false;
138static bool button_up=false;
139static bool chord_ready=false;
140static  bool ctrl_key=false;
141static bool caps_lock_key=false;
142static bool shift_key=false;
143static  bool alt_key=false;
144int DOWN=0;
145int ACROSS=0;
146
147static int RHAND=0;
148static  int LHAND=0;
149
150    noInterrupts();           // disable all interrupts
151if  (Debounced_State && left_Debounced_State){RHAND=Debounced_State;LHAND=left_Debounced_State;chord_ready=true;}//store  chord and flag as ready
152if (!Debounced_State || !left_Debounced_State){if(chord_ready){button_up=true;}}    
153    interrupts();             // enable all interrupts
154
155
156
157if(button_up  && chord_ready)
158{
159chord_ready=false;
160button_up=false;
161do_character=true;
162
163//from  patent 4,775,225 (modified)  
164//'BYTES FROM "DEVICE"
165//The original binary  values have been inverted
166   if (RHAND==128){DOWN=0;}
167   if (RHAND==64){DOWN=1;}
168   if (RHAND==32){DOWN=2;}                  //CONVERT BYTE VALUE TO INDEX
169   if  (RHAND==16){DOWN=3;}                  //VALUE FOR LEFT HAND
170   if (RHAND==8){DOWN=4;}
171   if (RHAND==4){DOWN=5;}
172   if (RHAND==2){DOWN=6;}
173   if (RHAND==1){DOWN=7;}
174   if (LHAND==128){ACROSS=0;}
175   if (LHAND==64){ACROSS=1;}
176   if (LHAND==32){ACROSS=2;}
177   if (LHAND==16){ACROSS=3;}                  //CONVERT BYTE VALUE TO INDEX
178   if (LHAND==8){ACROSS=4;}                  //VALUE FOR RIGHT HAND
179   if (LHAND==4){ACROSS=5;}   
180   if (LHAND==2){ACROSS=6;}
181   if (LHAND==1){ACROSS=7;}
182//READ CHARACTER  FROM TABLE
183//end - from patent 4,775,225 (modified)
184//NOTE DOWN & ACROSS have  default values of zero if no match
185//Example press 2 right hand keys(DOWN) and  s4_a(ACROSS) gives letter m(DOWN=0;ACROSS=1)
186}
187
188if (do_character) 
189{
190  do_character=false;
191
192  switch (key_table[ACROSS][DOWN]){
193    
194    //control  key
195    case 128: ctrl_key=true;digitalWrite(ctrl_led,HIGH);break;
196
197    //caps  lock key
198    case 193:caps_lock_key=!caps_lock_key;
199              if(caps_lock_key){digitalWrite(caps_lock_led,HIGH);}
200                  else{digitalWrite(caps_lock_led,LOW);}break;//toggle caps lock  key
201
202    //shift key              
203    case 129:shift_key=true;digitalWrite(caps_lock_led,HIGH);break;              
204                  
205    default : if(!ctrl_key && !caps_lock_key  && !shift_key){Keyboard.write((unsigned char)key_table[ACROSS][DOWN]);}
206    
207              if(ctrl_key)//control key only
208              {Keyboard.press(128);//control  on
209               Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
210               Keyboard.releaseAll();//control off
211               ctrl_key=false;
212               digitalWrite(ctrl_led,LOW);} 
213                        
214              if(shift_key  && !caps_lock_key)//shift only
215              {Keyboard.press(129);//shift on
216               Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
217               Keyboard.releaseAll();//shift  off
218               shift_key=false;
219               digitalWrite(caps_lock_led,LOW);}
220                 
221              if(caps_lock_key && !shift_key)//caps lock only
222              {
223               if (isAlpha((unsigned char)key_table[ACROSS][DOWN]))
224               {
225                Keyboard.press(129);
226                Keyboard.press((unsigned  char)key_table[ACROSS][DOWN]);
227                Keyboard.releaseAll();
228                }
229               else
230               {
231                Keyboard.press((unsigned  char)key_table[ACROSS][DOWN]);
232                Keyboard.releaseAll();
233                }
234                } 
235                                                            
236              if(shift_key && caps_lock_key)//shift and caps lock
237              {  if (isAlpha((unsigned char)key_table[ACROSS][DOWN]))
238                {
239                Keyboard.press((unsigned  char)key_table[ACROSS][DOWN]);
240                Keyboard.releaseAll();
241                shift_key=false;
242                }
243              else
244                {
245                Keyboard.press(129);//shift  on
246                Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
247                Keyboard.releaseAll();//shift off
248                shift_key=false;
249                }
250                }break;
251                                      
252    }
253
254}
255
256
257}
258
259
260//my_functions
261ISR(TIMER1_COMPA_vect)          // timer compare interrupt service routine
262{
263//
264//read buttons
265  uint8_t temp=0x00;
266  uint8_t left_temp=0x00;
267  
268  left_temp|=!digitalRead(button_1)<<6;left_temp|=!digitalRead(button_9)<<7;
269  left_temp|=!digitalRead(button_2)<<4;left_temp|=!digitalRead(button_10)<<5;
270  left_temp|=!digitalRead(button_3)<<2;left_temp|=!digitalRead(button_11)<<3;
271  left_temp|=!digitalRead(button_4)<<0;left_temp|=!digitalRead(button_12)<<1;
272  
273  temp|=!digitalRead(button_5)<<6;temp|=!digitalRead(button_13)<<7;
274  temp|=!digitalRead(button_6)<<4;temp|=!digitalRead(button_14)<<5;
275  temp|=!digitalRead(button_7)<<2;temp|=!digitalRead(button_15)<<3;
276  temp|=!digitalRead(button_8)<<0;temp|=!digitalRead(button_16)<<1;
277            
278//debounce
279  uint8_t i,j;
280
281//for right hand
282  State[Index]=  temp;
283  ++Index;
284  j=0xFF;
285  for (i=0;i<MAX_CHECKS;i++){j=j&State[i];}
286  Debounced_State=j;
287  if(Index>=MAX_CHECKS){Index=0;} 
288
289//for left hand  left_
290  left_State[left_Index]= left_temp;
291  ++left_Index;
292  j=0xFF;
293  for (i=0;i<MAX_CHECKS;i++){j=j&left_State[i];}
294  left_Debounced_State=j;
295  if(left_Index>=MAX_CHECKS){left_Index=0;}
296}
297//-----------end------------  
298

#include <Keyboard.h>
//
//left buttons
#define button_1 5
#define  button_2 6
#define button_3 7
#define button_4 8
#define button_9  SCK
#define  button_10 MISO
#define button_11 A5
#define button_12 A4

//right buttons
#define  button_5 9
#define button_6 10
#define button_7 11
#define button_8 12//A1
#define  button_13 A3
#define button_14 A2
#define button_15 A1//12
#define button_16  A0

#define caps_lock_led MOSI
#define ctrl_led  1
//alt has not been  coded into table 
#define alt_led  0
//On my original pcb I wired fn_led to  pin TX, which I couldn't get to work
#define fn_led 4 


//from patent  4,775,225 (modified)-
//Notes: 
//Patent table 3, which I used to create the  table below, lists g twice and ommits 6
//Patent tables 1 & 2 list 6 as occuring  at 0001 0010 (sw4_t and sw7_t), the other g is in its correct place
//Placement  of ! and ? is transposed in table 3 compared to tables 1 and 2 - I chose to follow  table 3
//Tables 1 and 2 list both numbers 3 and 5 as code 2000 0001 - where  2 means switch pressed away from you and 1 is switch toward you
//From table  3
//3 is code 2000 0001
//5 is code 2000 0002
//I have redesignated uppercase(UC)  and lowercase(LC)
//code 0010 2000 used for shift
//code 0020 1000 used for  caps lock
//
//Warning on char codes
//Characters are sent as if from a  US keyboard
//Characters change if receiving computer is not set up for US keyboard
//Example:
//In  my case:
//@ becomes "
//" becomes @
//# becomes 
//See:
//https://forum.arduino.cc/index.php?topic=428331.0
//Retrieved  28/Dec/2017

const unsigned char key_table[8][8]{'j','m','y','0','(','+','2','4',
                                    'k','p','z','1',')','"','3','5',
                                    ',',';','$','@','\	',194,'\\'','%',//F1  escape(\\) required to allow character ' in table  
                                    '.',':','#','*',128,195,'=','\\b',//CT  F2 
                                    'u',129,'o','n','-','?','q','w',//LC  as shift
                                    193,'\n','i','s','!','/','v','x',//UC  as caps lock
                                    ' ','t','h','d','6','8','b','f',
                                    'e','a','r','l','7','9','c','g'};
//end -  from patent 4,775,225 (modified)

//required to debounce switch
#define  MAX_CHECKS 10
//for right hand
volatile uint8_t Debounced_State=0;//accessed  by isr and main loop code
uint8_t State[MAX_CHECKS]={0};
uint8_t Index=0;

//for  left hand
volatile uint8_t left_Debounced_State=0;//accessed by isr and main  loop code
uint8_t left_State[MAX_CHECKS]={0};
uint8_t left_Index=0;

//  the setup function runs once when you press reset or power the board
void setup()  {

          pinMode(button_1,INPUT_PULLUP);
          pinMode(button_2,INPUT_PULLUP);
          pinMode(button_3,INPUT_PULLUP);
          pinMode(button_4,INPUT_PULLUP);
          pinMode(button_5,INPUT_PULLUP);
          pinMode(button_6,INPUT_PULLUP);
          pinMode(button_7,INPUT_PULLUP);
          pinMode(button_8,INPUT_PULLUP);
          
          pinMode(button_9,INPUT_PULLUP);
          pinMode(button_10,INPUT_PULLUP);
          pinMode(button_11,INPUT_PULLUP);
          pinMode(button_12,INPUT_PULLUP);
          pinMode(button_13,INPUT_PULLUP);
          pinMode(button_14,INPUT_PULLUP);
          pinMode(button_15,INPUT_PULLUP);
          pinMode(button_16,INPUT_PULLUP);

//led  setup
          pinMode(caps_lock_led,OUTPUT);
          pinMode(ctrl_led,OUTPUT);
          pinMode(alt_led,OUTPUT);
          pinMode(fn_led,OUTPUT);

//test  led's
          digitalWrite(caps_lock_led,HIGH);
          digitalWrite(ctrl_led,HIGH);
          digitalWrite(alt_led,HIGH);
          digitalWrite(fn_led,HIGH);
          delay(1000);
          digitalWrite(caps_lock_led,LOW);
          digitalWrite(ctrl_led,LOW);
          digitalWrite(alt_led,LOW);
          digitalWrite(fn_led,LOW);          

    // initialize timer1 
  noInterrupts();           // disable all interrupts
  TCCR1A = 0;
  TCCR1B = 0;
  TCNT1  = 0;

  OCR1A = 625;              //  compare match register  16MHX/256/100HZ 
  TCCR1B |= (1 << WGM12);   // CTC mode
  TCCR1B |= (1 << CS12);    // 256 prescaler 
  TIMSK1 |= (1 << OCIE1A);  //  enable timer compare interrupt
  interrupts();             // enable all interrupts


//  initialize control over the keyboard:
Keyboard.begin();
  
}

//  the loop function runs over and over again forever
void loop() {

static  bool do_character=false;
static bool button_up=false;
static bool chord_ready=false;
static  bool ctrl_key=false;
static bool caps_lock_key=false;
static bool shift_key=false;
static  bool alt_key=false;
int DOWN=0;
int ACROSS=0;

static int RHAND=0;
static  int LHAND=0;

    noInterrupts();           // disable all interrupts
if  (Debounced_State && left_Debounced_State){RHAND=Debounced_State;LHAND=left_Debounced_State;chord_ready=true;}//store  chord and flag as ready
if (!Debounced_State || !left_Debounced_State){if(chord_ready){button_up=true;}}    
    interrupts();             // enable all interrupts



if(button_up  && chord_ready)
{
chord_ready=false;
button_up=false;
do_character=true;

//from  patent 4,775,225 (modified)  
//'BYTES FROM "DEVICE"
//The original binary  values have been inverted
   if (RHAND==128){DOWN=0;}
   if (RHAND==64){DOWN=1;}
   if (RHAND==32){DOWN=2;}                  //CONVERT BYTE VALUE TO INDEX
   if  (RHAND==16){DOWN=3;}                  //VALUE FOR LEFT HAND
   if (RHAND==8){DOWN=4;}
   if (RHAND==4){DOWN=5;}
   if (RHAND==2){DOWN=6;}
   if (RHAND==1){DOWN=7;}
   if (LHAND==128){ACROSS=0;}
   if (LHAND==64){ACROSS=1;}
   if (LHAND==32){ACROSS=2;}
   if (LHAND==16){ACROSS=3;}                  //CONVERT BYTE VALUE TO INDEX
   if (LHAND==8){ACROSS=4;}                  //VALUE FOR RIGHT HAND
   if (LHAND==4){ACROSS=5;}   
   if (LHAND==2){ACROSS=6;}
   if (LHAND==1){ACROSS=7;}
//READ CHARACTER  FROM TABLE
//end - from patent 4,775,225 (modified)
//NOTE DOWN & ACROSS have  default values of zero if no match
//Example press 2 right hand keys(DOWN) and  s4_a(ACROSS) gives letter m(DOWN=0;ACROSS=1)
}

if (do_character) 
{
  do_character=false;

  switch (key_table[ACROSS][DOWN]){
    
    //control  key
    case 128: ctrl_key=true;digitalWrite(ctrl_led,HIGH);break;

    //caps  lock key
    case 193:caps_lock_key=!caps_lock_key;
              if(caps_lock_key){digitalWrite(caps_lock_led,HIGH);}
                  else{digitalWrite(caps_lock_led,LOW);}break;//toggle caps lock  key

    //shift key              
    case 129:shift_key=true;digitalWrite(caps_lock_led,HIGH);break;              
                  
    default : if(!ctrl_key && !caps_lock_key  && !shift_key){Keyboard.write((unsigned char)key_table[ACROSS][DOWN]);}
    
              if(ctrl_key)//control key only
              {Keyboard.press(128);//control  on
               Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
               Keyboard.releaseAll();//control off
               ctrl_key=false;
               digitalWrite(ctrl_led,LOW);} 
                        
              if(shift_key  && !caps_lock_key)//shift only
              {Keyboard.press(129);//shift on
               Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
               Keyboard.releaseAll();//shift  off
               shift_key=false;
               digitalWrite(caps_lock_led,LOW);}
                 
              if(caps_lock_key && !shift_key)//caps lock only
              {
               if (isAlpha((unsigned char)key_table[ACROSS][DOWN]))
               {
                Keyboard.press(129);
                Keyboard.press((unsigned  char)key_table[ACROSS][DOWN]);
                Keyboard.releaseAll();
                }
               else
               {
                Keyboard.press((unsigned  char)key_table[ACROSS][DOWN]);
                Keyboard.releaseAll();
                }
                } 
                                                            
              if(shift_key && caps_lock_key)//shift and caps lock
              {  if (isAlpha((unsigned char)key_table[ACROSS][DOWN]))
                {
                Keyboard.press((unsigned  char)key_table[ACROSS][DOWN]);
                Keyboard.releaseAll();
                shift_key=false;
                }
              else
                {
                Keyboard.press(129);//shift  on
                Keyboard.press((unsigned char)key_table[ACROSS][DOWN]);
                Keyboard.releaseAll();//shift off
                shift_key=false;
                }
                }break;
                                      
    }

}


}


//my_functions
ISR(TIMER1_COMPA_vect)          // timer compare interrupt service routine
{
//
//read buttons
  uint8_t temp=0x00;
  uint8_t left_temp=0x00;
  
  left_temp|=!digitalRead(button_1)<<6;left_temp|=!digitalRead(button_9)<<7;
  left_temp|=!digitalRead(button_2)<<4;left_temp|=!digitalRead(button_10)<<5;
  left_temp|=!digitalRead(button_3)<<2;left_temp|=!digitalRead(button_11)<<3;
  left_temp|=!digitalRead(button_4)<<0;left_temp|=!digitalRead(button_12)<<1;
  
  temp|=!digitalRead(button_5)<<6;temp|=!digitalRead(button_13)<<7;
  temp|=!digitalRead(button_6)<<4;temp|=!digitalRead(button_14)<<5;
  temp|=!digitalRead(button_7)<<2;temp|=!digitalRead(button_15)<<3;
  temp|=!digitalRead(button_8)<<0;temp|=!digitalRead(button_16)<<1;
            
//debounce
  uint8_t i,j;

//for right hand
  State[Index]=  temp;
  ++Index;
  j=0xFF;
  for (i=0;i<MAX_CHECKS;i++){j=j&State[i];}
  Debounced_State=j;
  if(Index>=MAX_CHECKS){Index=0;} 

//for left hand  left_
  left_State[left_Index]= left_temp;
  ++left_Index;
  j=0xFF;
  for (i=0;i<MAX_CHECKS;i++){j=j&left_State[i];}
  left_Debounced_State=j;
  if(left_Index>=MAX_CHECKS){left_Index=0;}
}
//-----------end------------

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