// **********ds1620b.c

// Jonathan W. Valvano 1/15/02

 

// Copyright 2002 by Jonathan W. Valvano, valvano@uts.cc.utexas.edu 

//    You may use, edit, run or distribute this file 

//    as long as the above copyright notice remains 



// Interface between MC68HC812 and DS1620

// Uses SPI (solution to lab assignment)

// See Valvano, Embedded Microcomputer Systems, Chap 7

// bit	status	Configuration/Status Register meaning

// 7	DONE	1=Conversion done, 0=conversion in progress

// 6	THF	1=temperature above TH, 0=temperature below TH

// 5	TLF	1=temperature below TL, 0=temperature above TL

// 1	CPU	1=CPU control, 0=stand alone operation

// 0	1SHOT	1=one conversion and stop, 0=continuous conversions

// temperature 	digital value (binary)	digital value (hex)

// +125.0 C    011111010                 $0FA

//  +64.0 C    010000000                 $080

//   +1.0 C    000000010                 $002

//   +0.5 C    000000001                 $001

//      0 C    000000000                 $000

//   -0.5 C    111111111                 $1FF

//  -16.0 C    111100000                 $1E0

//  -55.0 C    110010010                 $192

// DS1620 MC68HC812A4

// 1 DQ    PS5

// 2 CLK   PS6

// 3 RST   PS7

// 4 GND   ground

// 5 TCOM  not connected

// 6 TLOW  not connected

// 7 THIGH not connected

// 8 Vcc   +5 V with bypass cap to ground



void DS1620_Init(void){ // PS7=RST=0

    DDRS=0xE0;   // PS6=CLK=SPI clock out

    PORTS=0x60;  // PS5=DQ=SPI bidirectional data

/* bit SP0CR1

 7 SPIE = 0   no interrupts

 6 SPE  = 1   enable SPI

 5 SWOM = 0   regular outputs?

 4 MSTR = 1   master

 3 CPOL = 1   output changes on fall

 2 CPHA = 1   and input clocked in on rise

 1 SSOE = 0   PS7 regular output DS1620 RST

 0 LSBF = 1   least significant bit first */

    SP0CR1=0x5D;

/* bit SP0CR2

 3 PUPS = 0   no internal pullups

 2 RDS  = 0   regular drive

 0 SPC0 = 1   bidirectional mode */

    SP0CR2=0x01;

    SP0BR=0x02; // 1MHz could be 2Mhz

    }

#define SPIF 0x80

void static out8(char code){ unsigned char dummy;

// assumes DDRS bit 5 is 1, output

   SP0DR=code;

   while((SP0SR&SPIF)==0); // gadfly wait for SPIF

   dummy=SP0DR;            // clear SPIF

}



void DS1620_Start(void){

   PORTS |= 0x80;   // PS7=RST=1

   out8(0xEE);

   PORTS &= 0x7F;}  // PS7=RST=0

void DS1620_Stop(void){

   PORTS |= 0x80;   // PS7=RST=1

   out8(0x22);

   PORTS &= 0x7F;}  // PS7=RST=0







void DS1620_WriteConfig(char data){

   PORTS |= 0x80;   // PS7=RST=1

   out8(0x0C);

   out8(data);

   PORTS &= 0x7F;}  // PS7=RST=0





void static out9(int code){ unsigned char dummy;

   SP0DR=0x00FF & code;    // lsbyte

   while((SP0SR&SPIF)==0); // gadfly wait for SPIF

   dummy=SP0DR;            // clear SPIF

   SP0DR=0x00FF&(code>>8); // msbyte

   while((SP0SR&SPIF)==0); // gadfly wait for SPIF

   dummy=SP0DR;            // clear SPIF

}

void DS1620_WriteTH(int data){

   PORTS |= 0x80;   // PS7=RST=1

   out8(0x01);

   out9(data);

   PORTS &= 0x7F;}  // PS7=RST=0

void DS1620_WriteTL(int data){

   PORTS |= 0x80;   // PS7=RST=1

   out8(0x02);

   out9(data);

   PORTS &= 0x7F;}  // PS7=RST=0



unsigned char static in8(void){ int n;

unsigned char result;

   DDRS &= 0xDF; // PS5=DQ input

   SP0DR=0;      // start shift register

   while((SP0SR&SPIF)==0); // gadfly wait for SPIF

   result=SP0DR;           // get data, clear SPIF

   DDRS |= 0x20; // PS5=DQ output

   return result;}

unsigned char DS1620_ReadConfig(void){

unsigned char value;

   PORTS |= 0x80;   // PS7=RST=1

   out8(0xAC);

   value=in8();

   PORTS &= 0x7F;   // PS7=RST=0

   return value;}



unsigned int static in9(void){ 

unsigned int result;

   DDRS &= 0xDF; // PS5=DQ input

   SP0DR=0;      // start shift register

   while((SP0SR&SPIF)==0); // gadfly wait for SPIF

   result=SP0DR;           // get LS data, clear SPIF

   SP0DR=0;      // start shift register

   while((SP0SR&SPIF)==0); // gadfly wait for SPIF

   if(SP0DR&0x01)          // get MS data, clear SPIF

      result |= 0xFF00;    // negative

   else

      result &= 0x00FF;    // positive

   DDRS |= 0x20; // PS5=DQ output

   return result;}



unsigned int DS1620_ReadTH(void){

unsigned int value;

   PORTS |= 0x80;   // PS7=RST=1

   out8(0xA1);

   value = in9();

   PORTS &= 0x7F;   // PS7=RST=0

   return value;}

unsigned int DS1620_ReadTL(void){

unsigned int value;

   PORTS |= 0x80;   // PS7=RST=1

   out8(0xA2);

   value = in9();

   PORTS &= 0x7F;   // PS7=RST=0

   return value;}



unsigned int DS1620_ReadT(void){

unsigned int value;

   PORTS |= 0x80;   // PS7=RST=1

   out8(0xAA);

   value = in9();

   PORTS &= 0x7F;   // PS7=RST=0

   return value;}