We have already explained, in previous projects, how works and communicate the IC DS1307 and MAX7219, so we will proceed further by developing electronic schematic and the software model.
Hardware setup:
I intend to display the clock and room temperature, on six digits with seven segment. The time will be displayed on digits for 5 seconds then for another 5 second it will be displayed the temperature and so on.
In my case, the clock and max7219 circuit are mounted separately on pcb.
Clock circuit is designed separately by me, but max7219 circuit is acquired from Mikroelektronika.
Electrical schematic is designed to include the complete circuit.
Physical realization is carried out on the breadboard with 2420 dots.
Video:
Circuit Diagram:
This schematic has a low difficulty level. Microcontroller used is PIC16F876A.
S1 is the master reset button, R1 is the resistor of pull-up button.
Crystal quartz used has 8Mhz.
ICSP connector is used to program the microcontroller (I use PICKIT2).
R1, R3, R5, R10 are pull-up resistors.
Diode D1 has a protective role.
All three buttons are part of: incrementing hour, incrementing minute and enter.
Communication between DS1307 and circuit board "breadboard" is established by five pins as follow (GND, SQW, SCL, SDA, 5VDC). SQW pin is not used in this project.
We used a battery of 3vcc to ensure the functioning of the internal clock of DS1307 IC's, even if it is disconnected from 5 VDC.
Communication between max7219 circuit and microcontroller is set by pins RC0 (CS), RC1 (CLK) and RC2 (MOSI) used for software SPI protocol.
IF you are planning to use the "Serial 7-Seg 8-Digit Board" from mikroelektronika, it is necessary to set the appropriate switches on the DIP switch SW1 to the ON position:
- Switch 1- MOSI
- Switch 4 - SCK
- Switch 7 - CS
The capacitors C8-C11 serve as power filtering. Preferably is that the capacitors filters to be as near by ICs.
Electronic schematic is built in Eagle Cad, free version.
Software:
The program is written in mikroC Pro for PIC (version v6.4.0).
Below is my software version:
/*
'*******************************************************************************
' Project name: Real Time Clock [DS1307 with Set Functions] & DS18B20 & max7219
' Description:
' With this experiment we wish to succed the next task:
' Display on 6 digits with 7 segment leds, the clock and the room
' temperature (in Celsius Degree).
' Setting the time helped by three buttons: hours, minutes and enter.
'
' The sign "-" to the negative temperature and the hundreds for the
' temperature value are displayed just if are used.
' The time is displayed 5 second then he display the temperature value
' in Celsius Degrees for other 5 seconds and the loop goes to infinite.
' Our clock, displays as shown below(but just in display time,
' not in set mode).
' Ex. of viewing in 7 segment display,6 digits :
' Display time, mode: Display temperature mode:
' __________ _________
' |__24.59.59| ~5 sec delay |____23.6C|
'
' Hardware configuration is:
' IC ds1307 is connected with our microcontroller trough RC3=SCL,
' RC4=SDA (I2C Connections),
' max7219 as follow:(CS at RC0, CLK at RC1 and MOSI(SDO) at RC2)
' DS18B20 is assigned to RC7,
' RB0,RB1 and RB3 are assigned to the buttons
' Buttons Menu: RB0= Enter, (It goes to set functions or exit from set functions)
' RB1= Minutes,
' RB2= Hours,
'
' Written by:
' Aureliu Raducu Macovei, 2014.
' Test configuration:
' MCU: PIC16F876A;
' Test.Board: WB-106 Breadboard 2420 dots;
' SW: MikroC PRO for PIC 2013 (version v6.4.0);
' Configuration Word:
' Oscillator: HS (8Mhz)on pins 9 and 10;
' Watchdog Timer: OFF;
' Power up Timer: OFF;
' Browun Out Detect: ON;
' Low Voltage Program: Disabled;
' Data EE Read Protect: OFF;
' Flash Program Write: Write Protection OFF;
' Background Debug: Disabled;
' Code Protect: OFF
'*******************************************************************************
*/
// Software SPI module connections for max7219
sbit SoftSpi_SDI at RC6_bit;
sbit SoftSpi_SDO at RC2_bit; // MOSI
sbit SoftSpi_CLK at RC1_bit;
sbit Chip_Select at RC0_bit;
sbit SoftSpi_SDI_Direction at TRISC6_bit;
sbit SoftSpi_SDO_Direction at TRISC2_bit;
sbit SoftSpi_CLK_Direction at TRISC1_bit;
sbit Chip_Select_Direction at TrisC0_bit;
// End Software SPI module connections for max7219
const unsigned short TEMP_RESOLUTION = 12; //This is resolution for ds18b20
unsigned temp;
unsigned sec, min1, hr, week_day, day, mn, year;
unsigned short mask(unsigned short num)
{
switch (num) // Define switch cases
{
case 0 : return 0x7E; // 0 for those values please study the datasheet max7219
case 1 : return 0x30; // 1
case 2 : return 0x6D; // 2
case 3 : return 0x79; // 3
case 4 : return 0x33; // 4
case 5 : return 0x5B; // 5
case 6 : return 0x5F; // 6
case 7 : return 0x70; // 7
case 8 : return 0x7F; // 8
case 9 : return 0x7B; // 9
case 10 : return 0x01; // Symbol '-'
case 11 : return 0x00; // Blank
case 12 : return 0x80; // Comma "," symbol
case 13 : return 0x43; // C
} //case end
}
void max7219_init()
{
Chip_Select = 0; // SELECT MAX
Soft_Spi_write(0x09); // Decode-Mode Register
Soft_Spi_write(0x00); // No decode for digits 7–0
Chip_Select = 1; // DESELECT MAX
Chip_Select = 0; // SELECT MAX
Soft_Spi_write(0x0A); // Intensity Register Format
Soft_Spi_write(0x01); // Segment luminosity intensity set to 3/32
Chip_Select = 1; // DESELECT MAX
Chip_Select = 0; // SELECT MAX
Soft_Spi_write(0x0B); // Scan-Limit Register Format
Soft_Spi_write(0x05); // Display digits 0 1 2 3 4 5
Chip_Select = 1; // DESELECT MAX
Chip_Select = 0; // SELECT MAX
Soft_Spi_write(0x0C); // Shutdown Register Format
Soft_Spi_write(0x01); // Normal Operation
Chip_Select = 1; // DESELECT MAX
Chip_Select = 0; // SELECT MAX
Soft_Spi_write(0x00); // No-Op
Soft_Spi_write(0xFF); // No test
Chip_Select = 1; // DESELECT MAX
}
char minute2,hour2;
void max7219_display_set_mode(unsigned minute2, unsigned hour2)
{
Chip_Select = 0; // select max7219
Soft_Spi_write(6); // digit 6
Soft_Spi_write(mask((hour2/10)%10)); // assign tens of hours
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(5); // digit 5
Soft_Spi_write ((mask(hour2%10))+ mask(12)); // assign units of hours
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(4); // digit 4
Soft_Spi_write(mask((minute2/10)%10)); // assign tens of minutes
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(3); // digit 3
Soft_Spi_write((mask(minute2%10))+mask(12)); // assign units of minutes
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(2); // digit 2
Soft_Spi_write (0); // set as blank
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(1); // digit 1
Soft_Spi_write (0); // set as blank
Chip_Select = 1; // deselect max7219
}
void max7219_display (unsigned sec, unsigned min, unsigned hr)
{
Chip_Select = 0; // select max7219
Soft_Spi_write(6); // digit 6
Soft_Spi_write(mask((hr/10)%10)); // assign tens of hours
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(5); // digit 5
Soft_Spi_write ((mask(hr%10))+ mask(12)); // assign units of hours
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(4); // digit 4
Soft_Spi_write(mask((min/10)%10)); // assign tens of minutes
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(3); // digit 3
Soft_Spi_write((mask(min%10))+mask(12)); // assign units of minutes
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(2); // digit 2
Soft_Spi_write (mask((sec/10)%10)); // assign tens of seconds
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(1); // digit 1
Soft_Spi_write (mask(sec%10)); // assign units of seconds
Chip_Select = 1; // deselect max7219
}
//-----Reads time and date information from RTC (DS1307)
void Read_Time(unsigned *sec, unsigned *min, unsigned *hr, unsigned *week_day,
unsigned *day, unsigned *mn, unsigned *year)
{
I2C1_Start();
I2C1_Wr(0xD0);
I2C1_Wr(0);
I2C1_Repeated_Start();
I2C1_Wr(0xD1);
*sec =I2C1_Rd(1);
*min =I2C1_Rd(1);
*hr =I2C1_Rd(1);
*week_day =I2C1_Rd(1);
*day =I2C1_Rd(1);
*mn =I2C1_Rd(1);
*year =I2C1_Rd(0);
I2C1_Stop();
}//~
//-----------------start write time routine------------------
void Write_Time(unsigned minute, unsigned hour)
{
unsigned tmp1, tmp2;
tmp1 = minute / 10; // assign values from variables
tmp2 = minute % 10; // assign values from variables
minute = tmp1 * 16 + tmp2; // assign values from variables
tmp1 = hour / 10; // assign values from variables
tmp2 = hour % 10; // assign values from variables
hour = tmp1 * 16 + tmp2; // assign values from variables
I2C1_Start(); // issue start signal
I2C1_Wr(0xD0); // address DS1307
I2C1_Wr(0); // start from word at address (REG0)
I2C1_Wr(0x80); // write $80 to REG0. (pause counter + 0 sec)
I2C1_Wr(minute); // write minutes word to (REG1)
I2C1_Wr(hour); // write hours word (24-hours mode)(REG2)
I2C1_Wr(0x00); // write 6 - Saturday (REG3)
I2C1_Wr(0x00); // write 14 to date word (REG4)
I2C1_Wr(0x00); // write 5 (May) to month word (REG5)
I2C1_Wr(0x00); // write 01 to year word (REG6)
I2C1_Wr(0x80); // write SQW/Out value (REG7)
I2C1_Stop(); // issue stop signal
I2C1_Start(); // issue start signal
I2C1_Wr(0xD0); // address DS1307
I2C1_Wr(0); // start from word at address 0
I2C1_Wr(0); // write 0 to REG0 (enable counting + 0 sec)
I2C1_Stop(); // issue stop signal
}
//-----------------end write time routine------------------
//-------------------- Formats date and time
void Transform_Time(unsigned *sec, unsigned *min, unsigned *hr,
unsigned *week_day, unsigned *day, unsigned *mn, unsigned *year)
{
*sec = ((*sec & 0x70) >> 4)*10 + (*sec & 0x0F);
*min = ((*min & 0xF0) >> 4)*10 + (*min & 0x0F);
*hr = ((*hr & 0x30) >> 4)*10 + (*hr & 0x0F);
*week_day =(*week_day & 0x07);
*day = ((*day & 0xF0) >> 4)*10 + (*day & 0x0F);
*mn = ((*mn & 0x10) >> 4)*10 + (*mn & 0x0F);
*year = ((*year & 0xF0)>>4)*10+(*year & 0x0F);
}//~
void blink_min()
{
Chip_Select = 0; // select max7219
Soft_Spi_write(4); // digit 4
Soft_Spi_write(0); // set as blank
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(3); // digit 3
Soft_Spi_write(0); // set as blank
Chip_Select = 1;
delay_ms(50); // 50ms delay
max7219_display_set_mode(minute2,hour2); // display those values
delay_ms(50); // 50ms delay
}
void blink_hr()
{
Chip_Select = 0; // select max7219
Soft_Spi_write(6); // digit 6
Soft_Spi_write(0); // set as blank
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(5); // digit 5
Soft_Spi_write(0); // set as blank
Chip_Select = 1; // deselect max7219
delay_ms(50); // 50ms delay
max7219_display_set_mode(minute2,hour2); // display those values
delay_ms(50); // 50ms delay
}
char setuptime=0;
unsigned count=0;
void Press_Switch()
{
if(button(&portb,0,1,0)) // check if button RB0 is pressed
{
Delay_ms(200);
setuptime = !setuptime; // switch that value;
if(setuptime)
{
hour2=hr;
minute2=min1;
max7219_display_set_mode(minute2,hour2); // display those values
}
else
{
hr=hour2;
min1=minute2;
Write_Time(min1,hr);
max7219_display_set_mode(minute2,hour2);
}
}
if(Setuptime)
{
if(button(&portb,1,1,0))
{
Delay_ms(150);
minute2++;
if(minute2 > 59)
minute2=0;
blink_min();
}
if(button(&portb,2,1,0))
{
Delay_ms(150);
hour2++;
if(hour2 > 23)
hour2=0;
blink_hr();
}
}
}
// Starts ds18b20 declarations
void ds18b20(unsigned int temp2write)
{
const unsigned short RES_SHIFT = TEMP_RESOLUTION - 8;
unsigned temp_whole;
unsigned int temp_fraction;
unsigned short isNegative = 0x00;
// Check if temperature is negative
if (temp2write & 0x8000)
{
temp2write = ~temp2write + 1;
isNegative = 1;
}
// Extract temp_whole
temp_whole = temp2write >> RES_SHIFT ;
// Extract temp_fraction and convert it to unsigned int
temp_fraction = temp2write << (4-RES_SHIFT);
temp_fraction &= 0x000F;
temp_fraction *= 625; // 625 for ds18b20 and 5000 for ds1820;
Chip_Select = 0; // select max7219
Soft_Spi_write(1); // digit 1
Soft_Spi_write(mask(13)); // write C symbol
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(2); // Set digit number 3
Soft_Spi_write(mask(temp_fraction /1000)); // assigne as fraction
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(3); // Set digit number 3
Soft_Spi_write((mask(temp_whole%10))+mask(12)); // Assigne as ones
Chip_Select = 1; // deselect max7219
Chip_Select = 0; // select max7219
Soft_Spi_write(4); // Set digit number 4
Soft_Spi_write (mask((temp_whole/10)%10)); // Assigne as tens
Chip_Select = 1; // deselect max7219
if (isNegative == 1)
{
Chip_Select = 0; // select max7219
Soft_Spi_write(5); // Set digit number 5
Soft_Spi_write(mask(10)); // Assigne as symbol "-"
Chip_Select = 1; // deselect max7219
}
else
{
if(isNegative ==0 && temp_whole/100==0)
{
Chip_Select = 0; // select max7219
Soft_Spi_write(5); // Set digit number 5
Soft_Spi_write(mask(11)); // Assign as blank
Chip_Select = 1; // deselect max7219
}
else
{
Chip_Select = 0; // select max7219
Soft_Spi_write(5); // Set digit number 5
Soft_Spi_write(mask(temp_whole/100)); // Assign the hundreds
Chip_Select = 1; // deselect max7219
}
}
Chip_Select = 0; // select max7219
Soft_Spi_write(6); // Set digit number 6
Soft_Spi_write(0); // Assign value 0
Chip_Select = 1; // deselect max7219
}// End ds18b20 declarations
void interrupt()
{
if(setuptime)
count=0;
else
count++; // Interrupt causes count to be incremented by 1
TMR0 = 0; // Timer TMR0 is returned its initial value
INTCON = 0x20; // Bit T0IE is set, bit T0IF is cleared
}
void main()
{
CMCON |= 7; // Disable Comparators
OPTION_REG = 0x84; // Prescaler Rate Selected at 1:32;
TMR0 = 0; // Reset timer;
INTCON = 0xA0; // Disable interrupt PEIE,INTE,RBIE,T0IE
Chip_Select_Direction = 0; // Set RC0 pin as output
Soft_Spi_init(); // Initialize software SPI module
max7219_init(); // initialize max7219
I2C1_Init(100000); // initialize I2C
while (1) // and here, our while loope
{
Press_Switch();
if(!setuptime)
{
if(count<=1400) // ~ 5 seconds
{
Read_Time(&sec,&min1,&hr,&week_day,&day,&mn,&year); // read time from RTC(DS1307)
Transform_Time(&sec,&min1,&hr,&week_day,&day,&mn,&year); // format date and time
max7219_display(sec,min1, hr);
}
else
{
if(count>1400) // ~ 5 seconds
{
//Perform temperature reading
Ow_Reset(&PORTC, 7); // Onewire reset signal
Ow_Write(&PORTC, 7, 0xCC); // Issue command SKIP_ROM
Ow_Write(&PORTC, 7, 0x44); // Issue command CONVERT_T
Ow_Reset(&PORTC, 7);
Ow_Write(&PORTC, 7, 0xCC); // Issue command SKIP_ROM
Ow_Write(&PORTC, 7, 0xBE); // Issue command READ_SCRATCHPAD
temp = Ow_Read(&PORTC, 7); // Next Read Temperature and Read Byte 0 from Scratchpad
// Then read Byte 1 from Scratchpad and shift 8 bit left and add the Byte 0
temp = (Ow_Read(&PORTC, 7) << 8) + temp;
ds18b20(temp); //Format and display result on digits.
}
}
if(count>2800)
count = 0;
}
}
}
