> The TI interface is pulled high by resisters, never driven high. The proper
> connection would use two i/o lines. They should be input at all times unless
> you are driving the line low:
>
> PIN = LOW
> TRIS = 0 (output)
> delay
> TRIS = 1 (input)
>
> -Adam
>
> Andrew Seddon wrote:
> >
> > Sorry for the large post but I have no website.
> >
> > Well there`s good news and bad news. First off I have kind of got the
> > interface routines working. I say that because it sometimes works and
> > sometimes dosn`t. When I program my TI-83+ to read a byte then spew it back
> > out everything works fine. However when I try to make two TI`s, a 83+ and a
> > TI-82 talk through the PIC it dosn`t work!! Dammned if I know whats up..
> > Below is the code that I am using if anybody is interested or can find a bug
> > in it.
> >
> > BTW it`s in C2C but most of the custom function calls are self explanitary.
> > Sorry about the lack of comment.
> >
> > The calc variable is used as I have two calculators connected to one PIC,
> > both operating off the lower four bits of the A and B ports. The electrical
> > connection is just
> >
> > CALC 1 - WHITE - A0 + A2
> > - RED - A1 + A3
> >
> > CALC 2 - WHITE - B0 + B0
> > - RED - B1 + B3
> >
> > there are no resistors, diodes anyting, is that the problem??
> >
> > Here`s the code. Some redundent code commented out, was used it testing.
> >
> > //RS232 settings
> > #pragma RS232_TXPORT RC
> > #pragma RS232_RXPORT RC
> > #pragma RS232_TXPIN 0
> > #pragma RS232_RXPIN 1
> > #pragma RS232_BAUD 19200
> >
> > #pragma TURBO_MODE 1
> > #pragma CLOCK_FREQ 50000000
> >
> > char tris_a=255;
> > char tris_b=255;
> >
> > char bytetemp=0, bytetemp1=0;
> > char temp4=0;
> >
> > void sendDECNumber( char data )
> > {
> > putchar( '0' + data/100 );
> > putchar( '0' + (data%100)/10 );
> > putchar( '0' + data%10 );
> > }
> >
> > void sendHEXNumber( char data )
> > {
> > //Send high nibble
> > if( (data>>4) > 9 )
> > putchar( 'A' - 10 + (data>>4) );
> > else
> > putchar( '0' + (data>>4) );
> > //Send low nibble
> > if( (data&0x0F) > 9 )
> > putchar( 'A' - 10 + (data&0x0F) );
> > else
> > putchar( '0' + (data&0x0F) );
> > }
> >
> > void printf( const char* text )
> > {
> > char i = 0;
> > while( text[i] != 0 ) {
> > putchar( text[i++] );
> > delay_ms(10);
> > }
> > }
> >
> > void output_white_high(char calc)
> > {
> > if (calc == 1)
> > {
> > set_bit(tris_a, 0);
> > set_tris_a(tris_a);
> > }
> >
> > if (calc == 2)
> > {
> > set_bit(tris_b, 0);
> > set_tris_b(tris_b);
> > }
> > delay_ms(2);
> > }
> >
> > void output_white_low(char calc)
> > {
> > if (calc == 1)
> > {
> > clear_bit(tris_a, 0);
> > set_tris_a(tris_a);
> > }
> >
> > if (calc == 2)
> > {
> > clear_bit(tris_b, 0);
> > set_tris_b(tris_b);
> > }
> > delay_ms(2);
> > }
> >
> > void output_red_high(char calc)
> > {
> > if (calc == 1)
> > {
> > set_bit(tris_a, 1);
> > set_tris_a(tris_a);
> > }
> >
> > if (calc == 2)
> > {
> > set_bit(tris_b, 1);
> > set_tris_b(tris_b);
> > }
> > delay_ms(2);
> > }
> >
> > void output_red_low(char calc)
> > {
> > if (calc == 1)
> > {
> > clear_bit(tris_a, 1);
> > set_tris_a(tris_a);
> > }
> >
> > if (calc == 2)
> > {
> > clear_bit(tris_b, 1);
> > set_tris_b(tris_b);
> > }
> > delay_ms(2);
> > }
> >
> > char input_white(char calc)
> > {
> > if(calc == 1)
> > {
> > if(input_pin_port_a(2)) return 1;
> > else return 0;
> > }
> >
> > if(calc == 2)
> > {
> > if(input_pin_port_b(2)) return 1;
> > else return 0;
> > }
> > delay_ms(2);
> > }
> >
> > char input_red(char calc)
> > {
> > if(calc == 1)
> > {
> > if(input_pin_port_a(3)) return 1;
> > else return 0;
> > }
> >
> > if(calc == 2)
> > {
> > if(input_pin_port_b(3)) return 1;
> > else return 0;
> > }
> > delay_ms(2);
> > }
> >
> > char get_byte(char calc)
> > {
> > char bitcount=0, tempbit=0;
> > while(bitcount < 8)
> > {
> > while ((input_red(calc) == 1) && (input_white(calc) == 1)){nop();}
> > //putchar('1');
> > if (input_red(calc)==0)
> > {
> > output_white_low(calc);
> > while(input_red(calc)==0);
> > //putchar('2');
> > bitcount=bitcount + 1;
> > output_white_high(calc);
> > delay_ms(5);
> > }
> >
> > if (input_red(calc)==1)
> > {
> > output_red_low(calc);
> > while(input_white(calc)==0);
> > //putchar('3');
> > if (bitcount == 0) set_bit(tempbit, 0);
> > if (bitcount == 1) set_bit(tempbit, 1);
> > if (bitcount == 2) set_bit(tempbit, 2);
> > if (bitcount == 3) set_bit(tempbit, 3);
> > if (bitcount == 4) set_bit(tempbit, 4);
> > if (bitcount == 5) set_bit(tempbit, 5);
> > if (bitcount == 6) set_bit(tempbit, 6);
> > if (bitcount == 7) set_bit(tempbit, 7);
> >
> > bitcount=bitcount+1;
> > output_red_high(calc);
> > delay_ms(5);
> > }
> > }
> >
> > return tempbit;
> > }
> >
> > void transmit_high(char calc)
> > {
> > output_white_low(calc);
> >
> > while(input_red(calc)==1){nop();}
> >
> > output_white_high(calc);
> >
> > while(input_red(calc)==0){nop();}
> >
> > }
> >
> > void transmit_low(char calc)
> > {
> > output_red_low(calc);
> >
> > while(input_white(calc)==1){nop();}
> >
> > output_red_high(calc);
> >
> > while(input_white(calc)==0){nop();}
> >
> > }
> >
> > void send_byte(char byte, char calc)
> > {
> >
> > bytetemp=byte;
> >
> > while((input_red(calc)==0) || (input_white(calc)==0)){nop();}
> > delay_ms(2);
> >
> > asm{
> > bank _bytetemp
> > mov w, _bytetemp
> > and w, #%00000001
> > bank _bytetemp1
> > mov _bytetemp1, w
> > }
> > if(bytetemp1==0) transmit_low(calc);
> > else transmit_high(calc);
> >
> > asm{
> > bank _bytetemp
> > mov w, _bytetemp
> > and w, #%00000010
> > bank _bytetemp1
> > mov _bytetemp1, w
> > }
> > if(bytetemp1==0) transmit_low(calc);
> > else transmit_high(calc);
> >
> > asm{
> > bank _bytetemp
> > mov w, _bytetemp
> > and w, #%00000100
> > bank _bytetemp1
> > mov _bytetemp1, w
> > }
> > if(bytetemp1==0) transmit_low(calc);
> > else transmit_high(calc);
> >
> > asm{
> > bank _bytetemp
> > mov w, _bytetemp
> > and w, #%00001000
> > bank _bytetemp1
> > mov _bytetemp1, w
> > }
> > if(bytetemp1==0) transmit_low(calc);
> > else transmit_high(calc);
> >
> > asm{
> > bank _bytetemp
> > mov w, _bytetemp
> > and w, #%00010000
> > bank _bytetemp1
> > mov _bytetemp1, w
> > }
> > if(bytetemp1==0) transmit_low(calc);
> > else transmit_high(calc);
> >
> > asm{
> > bank _bytetemp
> > mov w, _bytetemp
> > and w, #%00100000
> > bank _bytetemp1
> > mov _bytetemp1, w
> > }
> > if(bytetemp1==0) transmit_low(calc);
> > else transmit_high(calc);
> >
> > asm{
> > bank _bytetemp
> > mov w, _bytetemp
> > and w, #%01000000
> > bank _bytetemp1
> > mov _bytetemp1, w
> > }
> > if(bytetemp1==0) transmit_low(calc);
> > else transmit_high(calc);
> >
> > asm{
> > bank _bytetemp
> > mov w, _bytetemp
> > and w, #%10000000
> > bank _bytetemp1
> > mov _bytetemp1, w
> > }
> > if(bytetemp1==0) transmit_low(calc);
> > else transmit_high(calc);
> > }
> >
> > main()
> > {
> > set_tris_a(255);
> > set_tris_b(255);
> > set_tris_c(11111110b);
> >
> > output_port_a(0);
> > output_port_b(0);
> > output_port_c(0);
> >
> > printf("\n\r START \n\r");
> >
> > //while(1){
> > //temp4=get_byte(1);
> > //sendHEXNumber(temp4);
> > //printf("\n\r");
> > //}
> >
> > while(1){
> > if(input_red(1)==0) {temp4=get_byte(1); send_byte(temp4, 2);
> > sendHEXNumber(temp4);}
> > if(input_white(1)==0) {temp4=get_byte(1); send_byte(temp4, 2);
> > sendHEXNumber(temp4);}
> > if(input_red(2)==0) {temp4=get_byte(2); send_byte(temp4, 1);
> > sendHEXNumber(temp4);}
> > if(input_white(2)==0) {temp4=get_byte(2); send_byte(temp4,
> > 1);sendHEXNumber(temp4);}
> > }
> >
> > }
> >
> > ________________________________________________________________________
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>
cs.rmit.edu.au
