implement one wire protocol on cc3200

We don't have an implementation - I'll have to study more on the protocol, and do few experiments (on CC3200) before making any suggestions.

-/Praneet

Hi,
thanks for your answer. I'm studying the protocol and I can detect the presence of temperature sensor as described in the datasheet.
But when I try to send commands to sensor, it doesn't give me a response. I suspect that the problem is in the timing. I'm using the UtilsDelay to implement the wait, but I've read that if the delay isn't accurate the sensor doesn't respond. Is there a library or a specific function to implement the wait?

Hi,

I want understand if is my code wrong

//this code write 1 or 0 on 1-wire bus

//it takes the bit as parameter

void write_bit(unsigned short bit){


GPIODirModeSet(GPIOA0_BASE, 0x8, GPIO_DIR_MODE_OUT);
PinConfigSet(PIN_58, PIN_STRENGTH_2MA|PIN_STRENGTH_6MA, PIN_TYPE_STD);

GPIO_IF_Set(3, g_uport, g_upin, 1);

UtilsDelay((3*80)/3);

GPIO_IF_Set(3, g_uport, g_upin, 0);


if(bit==0){
//must be 0 for 60 usec
UtilsDelay(60*80);



}
else{

//must be to 0 for 1 usec
UtilsDelay((3*80)/3);

}

GPIO_IF_Set(3, g_uport, g_upin, 1);

GPIODirModeSet(GPIOA0_BASE, 0x8, GPIO_DIR_MODE_IN);
PinConfigSet(PIN_58, PIN_STRENGTH_2MA|PIN_STRENGTH_6MA, PIN_TYPE_OD_PU);

if(bit==0){
//must be 0 for 60 usec
UtilsDelay((3*80)/3);



}
else{

//must be 0 for 1 usec
UtilsDelay(60*80);

}


}

Another things that I've read from datasheet is that I must use the Read Scratchpad to read temperature, after make Convert T request and after reset the bus. Now, I perform the Convert T command after I make Skip Rom command and I ask me if it's possible make Read scratchpad command after Skip rom command?
I've tried but it doesn't work. Where is the error?

For accurate delay, you could use CC3200's GPT and make the application wait till the timer expires.

-/Praneet

Hi,

I've modified my code to use a timer

in the main thread I set

MAP_PRCMPeripheralClkEnable(PRCM_TIMERA0, PRCM_RUN_MODE_CLK);
	MAP_PRCMPeripheralReset(PRCM_TIMERA0);
	MAP_TimerConfigure(TIMERA0_BASE,TIMER_CFG_ONE_SHOT);
	
	MAP_TimerPrescaleSet(TIMERA0_BASE,TIMER_A,0);
	Timer_IF_IntSetup(TIMERA0_BASE, TIMER_A, handletimer);
	

		GPIO_IF_GetPortNPin(3,
		                        &g_uportauscita,
		                        &g_upinuscita);


		set_output();


		//set output line to high
		GPIO_IF_Set(3, g_uport, g_upin, 1);

		UtilsDelay((10*80)/3);

		MAP_TimerLoadSet(TIMERA0_BASE,TIMER_A,(8000000/1000000)*(1));

		
		GPIO_IF_Set(3, g_uportauscita, g_upinuscita, 0);

		
		MAP_TimerEnable(TIMERA0_BASE,TIMER_A);







In the handler the code

Semaphore_pend(sem,BIOS_WAIT_FOREVER);

	//UART_PRINT("Overflow\n\r");

	if(counter_phases==0){
		
		if(counter_tick_GPT<480){

			GPIO_IF_Set(3, g_uport, g_upin, 0);
                        
                        //the timer count every 1 usec
			MAP_TimerLoadSet(TIMERA0_BASE,TIMER_A,(80000000/1000000)*(1));

			MAP_TimerEnable(TIMERA0_BASE,TIMER_A);

			contatore_tick_GPT++;


		}
		else{
			GPIO_IF_Set(3, g_uport, g_upin, 1);
			MAP_TimerLoadSet(TIMERA0_BASE,TIMER_A,(80000000/1000000)*(1));

			MAP_TimerEnable(TIMERA0_BASE,TIMER_A);
			set_input();

			counter_tick_GPT=0;
			counter_phasis=2;

		}


	}
	else if(counter_phasis==1){
		set_input();

		//incremento il contatore_fasi
		counter_phases=2;

		counter_tick_GPT=0;

		MAP_TimerLoadSet(TIMERA0_BASE,TIMER_A,(80000000/1000000)*(1));

		MAP_TimerEnable(TIMERA0_BASE,TIMER_A);



	}
	else if(counter_phasis==2){
		
		v  = GPIO_IF_Get(3, g_uport, g_upin);
		
		if(counter_tick_GPT<10){


			MAP_TimerLoadSet(TIMERA0_BASE,TIMER_A,(80000000/1000000)*(1));

			MAP_TimerEnable(TIMERA0_BASE,TIMER_A);

			counter_tick_GPT++;
		}
		else if((counter_tick_GPT>=10)&&(counter_tick_GPT<240)){
			


			MAP_TimerLoadSet(TIMERA0_BASE,TIMER_A,(80000000/1000000)*(1));

			MAP_TimerEnable(TIMERA0_BASE,TIMER_A);

			counter_tick_GPT++;








		}

	}
Semaphore_post(sem);

But after 15 usec from I set the output to high the sensor sets the bus to low only for 1 usec and not for 60 - 240 usecs. 

Are the timer load sets wrong?

I've considered that MCU frequency is 80Mhz

then to count 1 usec the time to count is (80000000/1000000)*(usecs)

Hi,
can you give me an information about One-wire?

I issue a skip ROM first of ask Read Scratchpad. Is correct or I need the Rom code of one-wire device?
I've only one device on 1-wire bus.

Hi,

If there is only one 1-wire device at bus, you can use skip ROM command. For multiple devices you need send ROM code.


Regards,
Jan

I have only one 1-wire device on the bus.

I'm using this function to read from bus when I ask to read scratchpad

unsigned char read_bit(void)
{
    unsigned char v;

    // Get port / pin addys
    unsigned int addr;
    unsigned char pin;
    GPIO_IF_GetPortNPin(0, &addr, &pin);


    osi_EnterCritical();

    // Mode Out
    output_mode();

    // Pull Line low to start timeslot
    GPIO_IF_Set(0, addr, pin, 0);


    UtilsDelay((3*80)/3);

    // Pull Line high
    GPIO_IF_Set(0, addr, pin, 1);


    // Mode In
    input_mode();

    // Delay 15usec
    //UtilsDelay((15*80)/3);
    UtilsDelay((10*80)/3);

    // read value
    v  = GPIO_IF_Get(0, addr, pin);

    osi_ExitCritical(0);

    // end of timeslot
    UtilsDelay((53*80)/3);

    // return value of DQ line
    return(v);
}

but I read only High value on the bus. It's a UtilsDelay time issue?

Thanks for help :D