Reading DS1990a ibutton with 16F Microcontroller - Page 2 - Electronic Circuits Projects Diagrams Free

konzen · 24th May 2008, 03:44 AM

oh one more thing, when i declare variables as byte, it doesn't turn blue the way int, for, if and while turns blue. i'm starting to believe that byte is not the correct choice of variable type. perhaps i'll try unsigned char.

Pommie · 24th May 2008, 05:20 AM

Do you realise that your code is waiting until the button is missing?

I indented and commented your code,

Code:

void main()
{
BYTE buffer[8];
BYTE i;
    while(TRUE){
        //printf("\r\nWaiting for a touch device...\r\n");

        while(!touch_present());	//wait for button to be missing
        output_high(PIN_B4);		//light LED
        delay_ms(200);			

        if(touch_present()) {		//if button is present
            output_low(PIN_B4);		//extinguish LED
            touch_write_byte(0x33);	//write command ReadRom
            for(i=0;i<8;++i)		//read the 8 byte ID
            	buffer[i]=touch_read_byte();
        }
        for(i=0; i<8; i++)
           putc(buffer[i]);

    }
}

The write_eeprom routine I used above is for the CCS compiler. I found it on page 243 of this document.

Mike.

Pommie · 24th May 2008, 05:23 AM

Try putting BYTE in lower case.

Mike.

konzen · 26th May 2008, 08:44 AM

Really?

Isn't that line saying 'as long as the ibutton is missing?'

Code:

void main()
{
BYTE buffer[8];
BYTE i;
    while(TRUE){
        //printf("\r\nWaiting for a touch device...\r\n");

        while(!touch_present());	//wait for button to be missing...'as long as ibutton is     
                                                   missing'
        output_high(PIN_B4);		//light LED
        delay_ms(200);			

        if(touch_present()) {		//if button is present
            output_low(PIN_B4);		//extinguish LED
            touch_write_byte(0x33);	//write command ReadRom
            for(i=0;i<8;++i)		//read the 8 byte ID
            	buffer[i]=touch_read_byte();
        }
        for(i=0; i<8; i++)
           putc(buffer[i]);

    }
}

Pommie · 26th May 2008, 09:21 AM

Quote:

Originally Posted by konzen

Really?

Isn't that line saying 'as long as the ibutton is missing?'

Yes, my mistake. I must have been asleep when I wrote that. Have you got it working now?

Mike.

konzen · 26th May 2008, 10:04 AM

haha lol,

So far when I touch the ibutton to the reader, fluctuations between 5V and 0 V were observed. This is rather good news. However, my MAX232 circuit is having a couple of problems so I can't transmit via RS232 to the PC.

I've tried the read function on the compiler to read the contents of the PIC but to no avail.

Any ideas?

in the meantime I'll be working on the MAX232 circuit

Pommie · 26th May 2008, 10:43 AM

A good way to test if your MAX232 circuit is working is to remove the pic from it's socket and connect the RX and TX pins (7 & 8) together. If you then run Hyperterminal and select flow control = none, you should see what you type echoed back.

As for storing the ID in the EEPROM, you should be able to read the EEPROM with your programmer. What programmer are you using?

Mike.

konzen · 26th May 2008, 10:49 AM

I see. Will try it. I'm using MPLAB IDE v7.60 which is readily available on the terminal I'm working on in uni.

konzen · 26th May 2008, 05:16 PM

I've tested my max232 circuit and its working fine. tried with the ibutton in place but nothing happens. I've tried just sending fixed hex values from the PIC but still nothing works.

example : putc(0x11)

I've defined #use RS232 in the header and all the relevant options such as baudrate, xmit and and rcv pin.

Will continue tmrw

konzen · 28th May 2008, 09:24 AM

Hey,

new update:
the max232 circuit works good. I can send values from the PIC to the PC with no problems now. however, I still can't get the PIC to read the ibutton.

the PIC always seems to loop in the wait state. No matter what I tried, I can't get it to respond to an ibutton touch.

I suspect that I did not define whether the pin i'm using to serve as an output or input that's being the cause to this.

however, since the bus is 1-wire, the pin is required to serve as both input and output. how do i do this?

btw i've also found out that byte and boolean are predefined variable types in the PIC header file so even though they don't turn blue when I type them there is nothing wrong.

And can you explain this area of code to me?

Code:

#ifndef TOUCH_PIN
#define TOUCH_PIN PIN_B0
#if defined(__PCH__)
#bit TOUCH_PIN_BIT = 0xF8A.0
#else
#bit TOUCH_PIN_BIT = 6.0
#endif
#endif

Thanks a bunch

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24th May 2008, 03:44 AM	(permalink)
konzen	oh one more thing, when i declare variables as byte, it doesn't turn blue the way int, for, if and while turns blue. i'm starting to believe that byte is not the correct choice of variable type. perhaps i'll try unsigned char.

24th May 2008, 05:23 AM	(permalink)
Pommie	Try putting BYTE in lower case. Mike.

26th May 2008, 10:04 AM	(permalink)
konzen	haha lol, So far when I touch the ibutton to the reader, fluctuations between 5V and 0 V were observed. This is rather good news. However, my MAX232 circuit is having a couple of problems so I can't transmit via RS232 to the PC. I've tried the read function on the compiler to read the contents of the PIC but to no avail. Any ideas? in the meantime I'll be working on the MAX232 circuit

26th May 2008, 10:43 AM	(permalink)
Pommie	A good way to test if your MAX232 circuit is working is to remove the pic from it's socket and connect the RX and TX pins (7 & 8) together. If you then run Hyperterminal and select flow control = none, you should see what you type echoed back. As for storing the ID in the EEPROM, you should be able to read the EEPROM with your programmer. What programmer are you using? Mike.

26th May 2008, 10:49 AM	(permalink)
konzen	I see. Will try it. I'm using MPLAB IDE v7.60 which is readily available on the terminal I'm working on in uni.

26th May 2008, 05:16 PM	(permalink)
konzen	I've tested my max232 circuit and its working fine. tried with the ibutton in place but nothing happens. I've tried just sending fixed hex values from the PIC but still nothing works. example : putc(0x11) I've defined #use RS232 in the header and all the relevant options such as baudrate, xmit and and rcv pin. Will continue tmrw

28th May 2008, 09:24 AM	(permalink)
konzen	Hey, new update: the max232 circuit works good. I can send values from the PIC to the PC with no problems now. however, I still can't get the PIC to read the ibutton. the PIC always seems to loop in the wait state. No matter what I tried, I can't get it to respond to an ibutton touch. I suspect that I did not define whether the pin i'm using to serve as an output or input that's being the cause to this. however, since the bus is 1-wire, the pin is required to serve as both input and output. how do i do this? btw i've also found out that byte and boolean are predefined variable types in the PIC header file so even though they don't turn blue when I type them there is nothing wrong. And can you explain this area of code to me? Code: #ifndef TOUCH_PIN #define TOUCH_PIN PIN_B0 #if defined(__PCH__) #bit TOUCH_PIN_BIT = 0xF8A.0 #else #bit TOUCH_PIN_BIT = 6.0 #endif #endif Thanks a bunch