www.micro-examples.com : PicOClock

Revision as of 21:52, 9 February 2012

An On-Screen-Display with only 5 components !

PicoOClock : Turn your oscilloscope into a digital clock

Let me introduce PicoOClock to you with this short video clip :

• 
• ==Circuit Schematic==
• ==C Source code==
• /*
• *******************************************************************************
• * PICOCLOCK : PIC Oscilloscope CLOCK
• *******************************************************************************
• *
• * This program shows how to display a digital clock on an oscilloscope
• * with a PIC and only 4 resistors.
• *
• * Circuit schematics :
• *
• * ------------+
• *
• * PIC

  ____

• * RB1 +----

  ____|-----+---------> to oscilloscope Y input

• *

  680 |

• *

  +-+

• *

  | | 330

• *

  +-+

• *

  ____ |

• * RB0 +----

  ____|-----+

• *

  680 |

• * ------------+ +-+
• *

  | 680

• * +-+
• *
• * -----
• * --- GND
• * -
• *
• * Oscilloscope setup :
• * set timebase to 0.1 ms, V/div = 1 V
• * select external trigger.
• *
• * source code for mikro C compiler V7.0.0.3
• * feel free to use this code at your own risks
• * and don't bother me if you get addicted watching this clock.
• *
• * target : PIC16 or PIC18, 16 Mhz crystal
• * HS clock, no watchdog.
• *
• * tested with PIC16F84A and PIC16F877A
• *
• * Author : Bruno Gavand, October 2007
• * see more details on http://www.micro-examples.com/
• *
• *******************************************************************************
• */
• /*
• * 2 bits R2R DAC gives 4 output levels :
• */
• /*
• * 10 digits 7 segment encoding + blank
• */
• /*
• * slot index for digit start
• */
• /*
• * time slot encoded line flags :
• * bit 0 is upper line
• * bit 1 is middle line
• * bit 2 is lower line
• * (if no line flag is set, spot is redirected to lowest line)
• * bit 6 is lower vertical bar
• * bit 7 is upper vertical bar
• */
• Unsigned char dIdx = 0 ; // time slot counter
• Unsigned char fIdx = 0 ; // frame counter
• Unsigned int scaler = 0 ; // RTC scaler
• Unsigned char ss = 0, mn = 0, hh = 0 ; // RTC
• /*
• * around 10 micro-second delay
• */
• Void delay10us()
• Delay us(10) ;
• /*
• * ISR
• */
• Void interrupt(void)
• If(INTCON.T0IF) // if timer 0 overflow
• Scaler++ ; // increment scaler
• Scaler = 0 ; // clear scaler
• Ss++ ; // next second
• If(ss == 60) // last second in minute ?
• Ss = 0 ; // clear second
• Mn++ ; // next minute
• If(mn == 60) // last minute in hour ?
• Mn = 0 ; // clear minute
• Hh++ ; // next hour
• If(hh == 24) // last hour in day ?
• Hh = 0 ; // clear hour
• LOW, HIGH, LOW, HIGH ;
• LOW, HIGH, LOW, HIGH ;
• LOW, HIGH, LOW, HIGH ;
• LOW, HIGH, LOW, HIGH ;
• LOW, HIGH, LOW, HIGH ;
• LOW, HIGH, LOW, HIGH ;
• LOW, HIGH, LOW, HIGH ;
• LOW, HIGH, LOW, HIGH ;
• MID, LOW, MID, LOW ;
• MID, LOW, MID, LOW ;
• MID, LOW, MID, LOW ;
• MID, LOW, MID, LOW ;
• MID, LOW, MID, LOW ;
• MID, LOW, MID, LOW ;
• MID, LOW, MID, LOW ;
• MID, LOW, MID, LOW ;
• MID, HIGH, MID, HIGH ;
• MID, HIGH, MID, HIGH ;
• MID, HIGH, MID, HIGH ;
• MID, HIGH, MID, HIGH ;
• MID, HIGH, MID, HIGH ;
• MID, HIGH, MID, HIGH ;
• MID, HIGH, MID, HIGH ;
• MID, HIGH, MID, HIGH ;
• If(dIdx == 7) // hour : minute separator
• LOW, Delay10us() ;
• MID, Delay10us() ;
• Else if(dIdx == 14) // minute : second separator
• LOW, Delay10us() ;
• MID, Delay10us() ;
• Switch(fIdx) // depending on frame index
• Case 0: // upper line
• HIGH ;
• Else
• ZERO ;
• Break ;
• Case 1: // middle line
• MID ;
• Else
• ZERO ;
• Break ;
• Case 2: // lower line
• LOW ;
• Else
• ZERO ;
• Break ;
• DIdx++ ; // next slot
• If(dIdx == SLOTS) // last slot ?
• DIdx = 0 ; // clear slot
• TRIGGER = 1 ; // triggers the scope
• FIdx++ ; // next frame
• If(fIdx == 3) // last frame ?
• FIdx = 0 ; // clear frame
• TRIGGER = 0 ; // end trigger
• INTCON.T0IF = 0 ; // clear timer 0 overflow
• /*
• * main entry
• */
• Void main()
• /*
• * set PORTA as digital I/O
• */
• ADCON1 = 7 ;
• CMCON = 7 ;
• TRISA = 0b110 ; // PORTA direction register
• PORTA = 0 ;
• TRISB = 0 ; // PORTB is output
• PORTB = 0 ;
• /*
• * clear buffers
• */
• Memset(&line, 0, sizeof(line)) ;
• Memset(display, 0, sizeof(display)) ;
• OPTION REG = 0b11011000 ; // timer 0 prescaler is 1:1
• INTCON = 0b10100000 ; // start interrupts
• For(;;) // main loop
• Unsigned char i ;
• If(KEY) // is a button pressed ?
• If(KEY MIN UP) // adjust minutes
• Ss = 0 ;
• Mn++ ;
• Else if(KEY HH UP) // adjust hours
• Ss = 0 ;
• Hh++ ;
• Mn %= 60 ; // prevent minute overflow
• Hh %= 24 ; // prevent hours overflow
• Delay ms(100) ; // debounce
• /*
• * prepare display buffer
• */
• /*
• * prepare time slot flags
• */
• Unsigned char s ;
• Unsigned char *p ;
• (*p).F0 = s.F0 ; // a segment
• (*p).F1 = s.F6 ; // g segment
• (*p).F2 = s.F3 ; // d segment
• (*p).F6 = s.F4 ; // e segment
• (*p).F7 = s.F5 ; // f segment
• P++ ; // next slot, center part of the digit
• (*p).F0 = s.F0 ; // a segment (continuation)
• (*p).F1 = s.F6 ; // g segment (continuation)
• (*p).F2 = s.F3 ; // d segment (continuation)
• P++ ; // next slot, right part of the digit
• (*p).F6 = s.F2 ; // b segment
• (*p).F7 = s.F1 ; // c segment
• ==Download project==
• Includes :
• * picoOSD C source code
• * picoOSD .HEX files
• ==Discussion and comments==