MSP430F149 microcontroller drives DS2762 to read and write C language program-EEWORLD

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Based on the MSP430F149 microcontroller driving the DS2762 read and write operation C language program, it can respond to keystrokes or other signals, read current and voltage, and perform corresponding processing.

//#include

#define uchar unsigned char

#define uint unsigned int

uint A,B,C,D,E,F,G,H,I,J; //The macro definition C in io430x14x is commented here, please note

#define IO_OUT P3DIR |= BIT0;

#define IO_INP P3DIR &= ~BIT0;

uint data;

/****************************************************** *****************************

Normalize read and write times

Initial debugging uses the parameter standard=1

// Pause for exactly 'tick' number of ticks = 0.25us

The actual measured A delay is 14Us

B125US

*************************************************** ****************************/

void SetSpeed(uint standard)

{

// Adjust tick values depending on speed

if (standard)

{

// Standard Speed

A = 6 * 4 / 2;

B = 64 * 4 / 2;

C = 60 * 4 / 2;

D = 10 * 4 / 2;

E = 9 * 4 / 2;

F = 55 * 4 / 2;

G = 0 / 2;

H = 480 * 4 / 2;

I = 70 * 4 / 2;

J = 410 * 4 / 2;

}

else

{

// Overdrive Speed

A = 1.5 * 4;

B = 7.5 * 4;

C = 7.5 * 4;

D = 2.5 * 4;

E = 0.75 * 4;

F = 7 * 4;

G = 2.5 * 4;

H = 70 * 4;

I = 8.5 * 4;

J = 40 * 4;

}

/****************************************************** *****************************

Delay Program

Note that you need to use an 8M crystal oscillator with a clock period of 125ns

*************************************************** ****************************/

void tickDelay(uint tick) // Implementation is platform specific

{

for(;tick>0;tick--);

}

/****************************************************** *****************************

Host reset pulse

When the receiving result is 0, it indicates that the slave responds

*************************************************** ****************************/

uchar OWTouchReset(void)

{

uchar result;

IO_OUT;

tickDelay(G);

P30 = 0; // Drives DQ low

tickDelay(H);

P30 = 1; // Releases the bus

tickDelay(I);

IO_INP;

result = P3IN & 0X01; // Sample for presence pulse from slave

tickDelay(J); // Complete the reset sequence recovery

return result; // Return sample presence pulse result

}

/****************************************************** *****************************

Like writing a DS2762 write a bit

Send a 1-Wire write bit. Provide 10us recovery time.

*************************************************** ****************************/

void OWWriteBit(uchar bit)

{

if (bit)

{

// Write '1' bit

P30 = 0; // Drives DQ low

tickDelay(A);

P30 = 1; // Releases the bus

tickDelay(B); // Complete the time slot and 10us recovery

}

else

{

// Write '0' bit

P30 = 0; // Drives DQ low

tickDelay(C);

P30 = 1; // Releases the bus

tickDelay(D);

}

}[page]

/****************************************************** *****************************

Reading a bit from the DS2762

Read a bit from the 1-Wire bus and return it. Provide 10us recovery time.

*************************************************** ****************************/

uchar OWReadBit(void)

{

uchar result;

P30 = 0; // Drives DQ low

tickDelay(A);

P30 = 1; // Releases the bus

tickDelay(E);

result = P3IN & 0X01; // Sample the bit value from the slave

tickDelay(F); // Complete the time slot and 10us recovery

return result;

}

/****************************************************** *****************************

Like writing a byte to the DS2762

Send a 1-Wire write. Provide 10us recovery time.

The DS2762 feature sends all commands and data with the low-order bit of the byte first, which is the opposite of most serial communication formats.

*************************************************** ****************************/

void OWWriteByte(uchar data)

{

uchar loop;

// Loop to write each bit in the byte, LS-bit first

for (loop = 0; loop < 8; loop++)

{

OWWriteBit(data & 0x01);

// shift the data byte for the next bit

data >>= 1;

}

/****************************************************** *****************************

Read a byte from the DS2762

*************************************************** ****************************/

uchar OWReadByte(void)

{

uchar loop, result=0;

for (loop = 0; loop < 8; loop++)

{

// shift the result to get it ready for the next bit

result >>= 1;

// if result is one, then set MS bit

if (OWReadBit())

result |= 0x80;

}

return result;

}

/****************************************************** *****************************

Send character function

Operations performed according to the time sequence of the paper diagram

It is not clear that sequential reads need to be optimized through testing.

Solution 1: Issue a read command and read one address twice. This should be correct.

Solution 2: Issue a read command and send two addresses to read twice

*************************************************** ****************************/

uint readvoltage(void)

{

uchar j = 1;

unsigned char volhigh,vollow;

while(j) //Check if 2762 responds

{

j = OWTouchReset();

}

OWWriteByte(0xcc); //

OWWriteByte(0x69);

OWWriteByte(0x0c);

vollow = OWReadByte();

volhigh = OWReadByte();

return ((volhigh<<8)|(vollow)); //Merge two bytes

}

/****************************************************** *****************************

Clock initialization

Note that you need to use an 8M crystal oscillator with a clock period of 125ns

*************************************************** ****************************/

void Init_clk(void)

{unsigned char i;

//Clock settings for the time base module

//When the MCU is powered on, the source of the MCLK master clock is selected by default as provided by DCO. The default DCO of the F1 series is 800KHZ.

//ACLK auxiliary clock defaults to XT1, XT1 is usually connected to 32768HZ crystal.

//The default SMCLK sub-clock is DCO, which is also 800KHZ.

//XT2 needs to be manually turned on and tested to see if it is turned on successfully.

BCSCTL1 &= ~(XT2OFF + XTS); //Start XT2 high-speed clock module

BCSCTL2 |= SELM1; //MCLK master clock selects XT2 as the clock source. TX2 input is not divided.

BCSCTL2 &= ~SELS; //SMCLK is selected as DCO as the clock source. (reference)

//Just turned on XT2, it takes a while for XT2 to enter a stable state. So you need to wait and detect the stable state.

//Usually use do...for syntax, which is the program writing method recommended by TI

{

IFG1 &=~OFIFG; //Clear OSCFault flag

for(i=0xff;i>0;i--) //Delay and wait for it to start and stabilize

;

}

while((IFG1 & OFIFG) !=0); //Check if the OSCFault flag is 0. If it is 0, it means XT2 is stable.

//Otherwise keep waiting...

}

/****************************************************** *****************************

Main function

Note that you need to use an 8M crystal oscillator with a clock period of 125ns

*************************************************** ****************************/

void main()

{

WDTCTL = WDTPW | WDTHOLD; // Stop watchdog

Init_clk();

SetSpeed(1);

while(1)

{

data = readvoltage();

}

Keywords：MSP430F149 Reference address：MSP430F149 microcontroller drives DS2762 to read and write C language program

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