//this code is working well for dht11 sensor with tm4c123gh6pm in ccs
#include <stdint.h>
#include <stdio.h>
#include <stdbool.h>
#include "inc/tm4c123gh6pm.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/sysctl.h"
#include "driverlib/interrupt.h"
#include "driverlib/gpio.h"
#include "driverlib/timer.h"
#include "driverlib/pin_map.h"
#include "driverlib/uart.h"
#include "driverlib/adc.h"
#include "driverlib/fpu.h"
#include "utils/uartstdio.h"
volatile int temp[43];
volatile int diff[43];
volatile unsigned int i=0;
volatile unsigned int j=0;
volatile unsigned int hh = 0;
volatile unsigned int hl = 0;
volatile unsigned int th = 0;
volatile unsigned int tl = 0;
volatile unsigned int checksum = 0;
volatile unsigned int check = 0;
volatile unsigned int dataok = 0 ;
// function prototypes
void init_timer(void);
void duty_cycle(void);
// global variables
uint32_t sys_clock;
uint32_t start = 0, end = 0, length = 0;
int main(void)
{
// Configure system clock at 40 MHz.
SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);
sys_clock = SysCtlClockGet();
// Enable the processor to respond to interrupts.
IntMasterEnable();
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB); //enable port B
GPIOPinTypeGPIOOutput(GPIO_PORTB_BASE, GPIO_PIN_6); //connect sensor at PB6
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_6, 0x00); //off PB6 for 18 ms
delayMs(18) ; //18ms delay
GPIOPinWrite(GPIO_PORTB_BASE, GPIO_PIN_6, 0xff); //on PB6
delayUs(40) ; //delay 40us
init_timer(); // timer initialisation and make PB6 as a input timer
TimerEnable(TIMER0_BASE, TIMER_BOTH);
int k,l,mul=1;
while(1)
{
if (i >= 42)
{
for (j = 1; j <= 8; j++) //first 8bit data is of first array index
{ // array {0,0,1,0,1,0,0,1}
if(diff[j]==1) //integer value is 41
{
for(l=0;l<8-j;l++)
mul=mul*2;
hh=hh+mul; //hh=41 when above array
}
mul=1; //hh is humidity integer
}
mul=1;
for (j = 9; j <= 16; j++)
{
if(diff[j]==1)
{
for(l=0;l<16-j;l++)
mul=mul*2;
hl=hl+mul; //hl is humidity after . with 0.1 multiple
}
mul=1;
}
mul=1;
for (j = 17; j <= 24; j++)
{
if(diff[j]==1)
{
for(l=0;l<24-j;l++)
mul=mul*2;
th=th+mul; //th temp integer
}
mul=1;
}
mul=1;
for (j = 25; j <= 32; j++)
{
if(diff[j]==1)
{
for(l=0;l<32-j;l++)
mul=mul*2;
tl=tl+mul; //tl after .
}
mul=1;
}
mul=1;
for (j = 33; j <= 40; j++)
{
if(diff[j]==1)
{
for(l=0;l<40-j;l++)
mul=mul*2;
checksum=checksum+mul; //last 8bit(last 8 index of array)
} //convert last 8 index into one integer
mul=1;
}
check = hh+hl+th+tl;
if (check == checksum) //check parity//last 8 index combined integer//addition of 32 index integer
{
dataok = 1;
break;
}
else
dataok = 0;
}
}
float humidity=hh+(0.1*hl); //humidity value in %
float temparature=th+(0.1*tl); //temp value in celsious
}
void init_timer(void)
{
// Enable and configure Timer0 peripheral.
SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER0);
// Initialize timer A to count up in edge time mode
TimerConfigure(TIMER0_BASE, (TIMER_CFG_SPLIT_PAIR | TIMER_CFG_A_CAP_TIME_UP ));
// Timer A records pos edge time
TimerControlEvent(TIMER0_BASE, TIMER_A, TIMER_EVENT_POS_EDGE);
//set the value that the timers count to max 0xffff
TimerLoadSet(TIMER0_BASE, TIMER_A, 0xffff);
//Configure the pin that the timer reads from (PB6)
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
GPIOPinConfigure(GPIO_PB6_T0CCP0);
GPIOPinTypeTimer(GPIO_PORTB_BASE, GPIO_PIN_6);
// Registers a interrupt function to be called when timer A hits a Pos edge event
IntRegister(INT_TIMER0A, duty_cycle); //positive edge timer
// Makes sure the interrupt is cleared
TimerIntClear(TIMER0_BASE, TIMER_CAPA_EVENT);
// Enable the indicated timer interrupt source.
TimerIntEnable(TIMER0_BASE, TIMER_CAPA_EVENT);
// The specified interrupt is enabled in the interrupt controller.
IntEnable(INT_TIMER0A);
}
//When positive edge is hit record the values and find the difference, and found data is 0 or 1
void duty_cycle(void)
{
TimerIntClear(TIMER0_BASE, TIMER_CAPA_EVENT);
start = TimerValueGet(TIMER0_BASE, TIMER_A);
temp[i] = start;
i += 1;
if (i>=3)
{
diff[i-2]=temp[i-1]-temp[i-2]; //timer interval when +ve edge found
if(diff[i-2]<4000) //when timer interval is less than 4000 means data 0 read
diff[i-2]=0;
else
diff[i-2]=1;
}
}
void delayMs(int ui32Ms)
{
SysCtlDelay((ui32Ms * SysCtlClockGet() /3/ 1000)); //ms delay
}
void delayUs(uint32_t ui32Us)
{
SysCtlDelay(ui32Us * (SysCtlClockGet() / 3 / 1000000)); //us delay
}
