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sareehy
Joined: 03 May 2016
Posts: 20
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 Posted: Mon Aug 14, 2017 2:51 pm |
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Thank you guys 
I tested the keypad using scope using only pull-up resistors tied to 5V
the signal was as in the following:
Would it be better to use external pull-up resistors or internal ?
Sorry for bothering you . 
Your effort is highly appreciated |
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temtronic
Joined: 01 Jul 2010
Posts: 9097
Location: Greensville,Ontario
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| Posted: Mon Aug 14, 2017 3:00 pm |
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Looks good to me, nice clean square edges, which is what you want.
The proof is pressing all the keys and confirm it works in the 'Real World'.
I use external 10K resistors only because some I/O pins on some PICS do NOT have internal pullups available. While it take a very small space on the PCB, it means the hardware is aways the same from product to product and I can substitute the PIC if I have to, without worrying if it'll work or have to change code.
Jay |
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sareehy
Joined: 03 May 2016
Posts: 20
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| Posted: Mon Aug 14, 2017 3:45 pm |
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| temtronic wrote: | Looks good to me, nice clean square edges, which is what you want.
The proof is pressing all the keys and confirm it works in the 'Real World'.
I use external 10K resistors only because some I/O pins on some PICS do NOT have internal pullups available. While it take a very small space on the PCB, it means the hardware is aways the same from product to product and I can substitute the PIC if I have to, without worrying if it'll work or have to change code.
Jay |
so just connect the keypad with pull-up resistor ^^
thank you temtronic |
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sareehy
Joined: 03 May 2016
Posts: 20
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| Posted: Fri Aug 18, 2017 8:27 am |
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Hi all ^_^
I tried to use pins rb4-rb7 as output.
I modified the kbd_1row as the following:
| Code: |
#if defined use_portb_kbd
#byte kbd = getenv("SFR:PORTB")
#else
#byte kbd = getenv("SFR:PORTD")
#endif
#define ROW0 (1 << 0) // Pin B0
#define ROW1 (1 << 1) // Pin B1
#define ROW2 (1 << 2) // Pin B2
#define ROW3 (1 << 3) // pin B3
#define ALL_ROWS (ROW0|ROW1|ROW2|ROW3)
#define ALL_PINS (ALL_ROWS)
// Keypad layout:
char const KEYS[4] = {'1','2','3','4'};
void kbd_init()
{
//port_b_pullups(0x0F);
set_tris_b(0x0f);
}
char kbd_getc(void)
{
static int1 kbd_down = FALSE;
static char last_key = '\0';
BYTE kchar;
BYTE row;
static unsigned int8 temp=0;
kchar='\0';
kbd = input_b()&0x0f;
if(kbd_down)
{
if((kbd & (ALL_ROWS))==(ALL_ROWS))
{
kbd_down=FALSE;
kchar=last_key;
last_key='\0';
}
}
else
{
if((kbd & (ALL_ROWS)) != (ALL_ROWS))
{
if((kbd & ROW0)==0)
row=0;
else if((kbd & ROW1)==0)
row=1;
else if((kbd & ROW2)==0)
row=2;
else if((kbd & ROW3)==0)
row=3;
last_key =KEYS[row];
kbd_down = TRUE;
}
}
delay_ms(10); // Debounce delay
return(kchar);
}
char kbd_pressed(void){
char keypress;
keypress=kbd_getc();
while(keypress=='\0'){
keypress=kbd_getc();
}
return (keypress);
}
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Test code:
| Code: |
#include <16F877A.h>
//#rom 0X2100= {11,14,0,16,4,27,0,0,0,0,0}
//#rom 0X2100= {0,0,0,0,0,0,0,0,0}
#use delay(clock=20000000)
#fuses HS,NOWDT,NOPROTECT,PUT, NOLVP
#use rs232(baud=9600, UART, ERRORS)
#use fast_io(b)
#define use_portb_kbd
#include "kbd_1row.c"
//======================================
void main()
{
char k;
printf("Ready\n\r");
//set_tris_b(0x0f);
kbd_init();
while(TRUE)
{
k=kbd_pressed();
printf("key:%c\n\r",k);
output_toggle(pin_b7);
}
}
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Pin B7 should toggle every key pressed but it remains low all the time.
I think the problem is here:
| Code: |
#if defined use_portb_kbd
#byte kbd = getenv("SFR:PORTB")
#else
#byte kbd = getenv("SFR:PORTD")
#endif
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| Code: |
kbd = input_b()&0x0f;
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Regards |
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sareehy
Joined: 03 May 2016
Posts: 20
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| Posted: Fri Aug 18, 2017 12:41 pm |
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hi,
i modified kbd_getc as the following
| Code: |
char kbd_getc(void)
{
static int1 kbd_down = FALSE;
static char last_key = '\0';
BYTE kchar;
BYTE row;
byte RDio=0;
static unsigned int8 temp=0;
kchar='\0';
//kbd = input_b()&0x0f;
RDio= input_b()&0x0f;
if(kbd_down)
{
if((kbd & (ALL_ROWS))==(ALL_ROWS))
{
kbd_down=FALSE;
kchar=last_key;
last_key='\0';
}
}
else
{
if((kbd & (ALL_ROWS)) != (ALL_ROWS))
{
if((kbd & ROW0)==0)
row=0;
else if((kbd & ROW1)==0)
row=1;
else if((kbd & ROW2)==0)
row=2;
else if((kbd & ROW3)==0)
row=3;
last_key =KEYS[row];
kbd_down = TRUE;
}
}
delay_ms(10); // Debounce delay
return(kchar);
}
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pins rb4-rb7 now working fine as o/p ^^
any comments on my modification ?
Regards |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19215
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| Posted: Fri Aug 18, 2017 12:48 pm |
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You have fiddled with the code without understanding it.
kbd is already defined as a variable to _input_ from the keyboard. That is what the #byte is doing.
In this line:
kbd = input_b()&0x0f;
You are reading portB, then writing the value back out to portB. No wonder it doesn't work....
The rest of the code correctly uses the kbd as input. |
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sareehy
Joined: 03 May 2016
Posts: 20
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| Posted: Fri Aug 18, 2017 4:13 pm |
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| Ttelmah wrote: | You have fiddled with the code without understanding it.
kbd is already defined as a variable to _input_ from the keyboard. That is what the #byte is doing.
In this line:
kbd = input_b()&0x0f;
You are reading portB, then writing the value back out to portB. No wonder it doesn't work....
The rest of the code correctly uses the kbd as input. |
thanks a lot
so no need to use this line ?
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Ttelmah
Joined: 11 Mar 2010
Posts: 19215
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| Posted: Fri Aug 18, 2017 10:51 pm |
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Exactly.
However it is important how your TRIS is being used. The code here relies on the keyboard bits being set as inputs. They will be provided you don't use a port wide output. You talk about outputting on the high four bits of the port. If you are using the standard output_high, or output_low on these, the low four bits will happily stay as they are. However if you did 'output_b' (port wide output), this would set the kbd bits as outputs and stop things working. |
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sareehy
Joined: 03 May 2016
Posts: 20
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| Posted: Sat Aug 19, 2017 12:58 am |
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| Ttelmah wrote: | Exactly.
However it is important how your TRIS is being used. The code here relies on the keyboard bits being set as inputs. They will be provided you don't use a port wide output. You talk about outputting on the high four bits of the port. If you are using the standard output_high, or output_low on these, the low four bits will happily stay as they are. However if you did 'output_b' (port wide output), this would set the kbd bits as outputs and stop things working. |
sorry for bothering you :(
| Code: |
#if defined use_portb_kbd
#byte kbd = getenv("SFR:PORTB")
#else
#byte kbd = getenv("SFR:PORTD")
#endif
#define ROW0 (1 << 0) // Pin B0
#define ROW1 (1 << 1) // Pin B1
#define ROW2 (1 << 2) // Pin B2
#define ROW3 (1 << 3) // pin B3
#define ALL_ROWS (ROW0|ROW1|ROW2|ROW3)
#define ALL_PINS (ALL_ROWS)
// Keypad layout:
char const KEYS[4] = {'1','2','3','4'};
void kbd_init()
{
//port_b_pullups(0x0F);
set_tris_b(0x0f);
}
char kbd_getc(void)
{
static int1 kbd_down = FALSE;
static char last_key = '\0';
BYTE kchar;
BYTE row;
static unsigned int8 temp=0;
kchar='\0';
//kbd = input_b();
if(kbd_down)
{
if((kbd & (ALL_ROWS))==(ALL_ROWS))
{
kbd_down=FALSE;
kchar=last_key;
last_key='\0';
}
}
else
{
if((kbd & (ALL_ROWS)) != (ALL_ROWS))
{
if((kbd & ROW0)==0)
row=0;
else if((kbd & ROW1)==0)
row=1;
else if((kbd & ROW2)==0)
row=2;
else if((kbd & ROW3)==0)
row=3;
last_key =KEYS[row];
kbd_down = TRUE;
}
}
delay_ms(20); // Debounce delay
return(kchar);
}
char kbd_pressed(void){
char keypress;
keypress=kbd_getc();
while(keypress=='\0'){
keypress=kbd_getc();
}
return (keypress);
}
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test code
| Code: |
#include <16F877A.h>
//#rom 0X2100= {11,14,0,16,4,27,0,0,0,0,0}
//#rom 0X2100= {0,0,0,0,0,0,0,0,0}
#use delay(clock=20000000)
#fuses HS,NOWDT,NOPROTECT,PUT, NOLVP
#use rs232(baud=9600, UART, ERRORS)
#use fast_io(b)
#define use_portb_kbd
#include "kbd_1row.c"
//======================================
void main()
{
char k;
printf("Ready\n\r");
//set_tris_b(0x0f);
kbd_init();
while(TRUE)
{
k=kbd_pressed();
printf("key:%c\n\r",k);
output_toggle(pin_b7);
}
}
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i modified kbd_1row and it worked fine..
thank you for your appreciated effort |
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