//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// SIMPLE RTOS EXAMPLE - VOLTMETER WITH RS232 OUTPUT
// This is a simple RTOS example. Analog voltage to be measured (between 0V
// and +5V) is connected to analog input AN0 of a PIC18F8520 type
// microcontroller. The microcontroller is operated from a 10MHz crystal. In
// addition, an LED is connected to port in RD7 of the microcontroller.
// RS232 serial output of the mirocontroller (RC6) is connected to a MAX232
// type RS232 voltage level converter chip. The output of this chip can be
// connected to the serial input of a PC (e.g., COM1) so that the measured
// voltage can be seen on the PC screen.
// The program consists of 3 tasks called "live", "Get_voltage", and “To_RS232”.
// Task "Live" runs every 200ms and it flashes the LED conencted to port pin
// RD7 of the microcontroller to indicate that the program is running and is
// ready to measure voltages.
// task "Get_voltage" reads analog voltage from port AN0 and then converts
// the voltage into millivolts and stores in a variable called Volts.
// Task "To_RS232" gets the measured voltage, converts it into a character
// array and then sends to the PC over the RS232 serial line. The serial line
// is configured to operate at 2400 Baud (higher Baud rates can also be used if
// desired).
////////////////////////////////////////////////////////////////////////////////////
#include <18F8520.h>
#device adc=10
#use delay (clock=10000000)
#use rs232(baud=2400,xmit=PIN_C6,rcv=PIN_C7)
///////////////////////////////////////////////////////////////////////////////
unsigned int16 adc_value;
unsigned int32 Volts;
///////////////////////////////////////////////////
// Define which timer to use and minor_cycle for RTOS
////////////////////////////////////////////////////
#use rtos(timer=0, minor_cycle=100ms)
///////////////////////////////////////////////////////////////////
// Declare TASK "Live" - called every 200ms
// This task flashes the LED on port RD7
#task(rate=200ms, max=1ms)
void Live()
{
output_toggle(PIN_D7); // Toggle RD7 LED
}
////////////////////////////////////////////////////////////////
// Declare TASK "Get_voltage" - called every 10ms
#task(rate=2s, max=100ms)
void Get_voltage()
{
adc_value = read_adc(); // Read A/D value
Volts = (unsigned int32)adc_value*5000;
Volts = Volts / 1024; // Voltage in mV
}
/////////////////////////////////////////////////////////////////////
// Declare TASK "To_RS232" - called every millisecond
#task(rate=2s, max=100ms)
void To_RS232()
{
printf("Measured Voltage = %LumV\n\r",Volts); // send to RS232
}
/////////////////////////////////////////////////////////////
// Start of MAIN program
//////////////////////////////////////////////////
void main()
{
set_tris_d(0); // PORTD all outputs
output_d(0); // Clear PORTD
set_tris_a(0xFF); // PORTA all inputs
setup_adc_ports(ALL_ANALOG); // A/D ports
//////////////////////////////////////////////////
setup_adc(ADC_CLOCK_DIV_32); // A/D clock
set_adc_channel(0); // Select channel 0 (AN0)
delay_us(10);
/////////////////////////////////////
rtos_run(); // Start RTOS
}
/////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////////
#include <18F8520.h>
#device adc=10
#use delay (clock=10000000)
#use rs232(baud=2400,xmit=PIN_C6,rcv=PIN_C7)
///////////////////////////////////////////////////////////////////////////////
unsigned int16 adc_value;
unsigned int32 Volts;
///////////////////////////////////////////////////
// Define which timer to use and minor_cycle for RTOS
////////////////////////////////////////////////////
#use rtos(timer=0, minor_cycle=100ms)
///////////////////////////////////////////////////////////////////

    
/////////////////////////////////////////////////////////////
// Start of MAIN program
//////////////////////////////////////////////////
void main()
{
set_tris_d(0); // PORTD all outputs
output_d(0); // Clear PORTD
set_tris_a(0xFF); // PORTA all inputs
setup_adc_ports(ALL_ANALOG); // A/D ports
////////////////////////////////////////////////////
setup_adc(ADC_CLOCK_DIV_32); // A/D clock
set_adc_channel(0); // Select channel 0 (AN0)
delay_us(10);
/////////////////////////////////////
rtos_run(); // Start RTOS
}
/////////////////////////////////////////////////////////////

///////////////////////////////////////////////////////////////////
// Declare TASK "Live" - called every 200ms
// This task flashes the LED on port RD7
#task(rate=200ms, max=1ms)
void Live()
{
output_toggle(PIN_D7); // Toggle RD7 LED
}
////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////
// Declare TASK “Get_voltage” – called every 10ms
#task(rate=2s, max=100ms)
void Get_voltage()
{
adc_value = read_adc(); // Read A/D value
Volts = (unsigned int32)adc_value*5000;
Volts = Volts / 1024; // Voltage in Mv
}
/////////////////////////////////////////////////////////////////////

Measured voltage = nnnn Mv

/////////////////////////////////////////////////////////////////////
// Declare TASK "To_RS232" - called every millisecond
#task(rate=2s, max=100ms)
void To_RS232()
{
printf("Measured Voltage = %LumV\n\r",Volts); // send to RS232
}
/////////////////////////////////////////////////////////////