//----------------------------------------------------------------------------------
char sht_write_byte(unsigned char value)
//----------------------------------------------------------------------------------
// writes a byte on the Sensibus and checks the acknowledge
{
unsigned char i,error=0;
for (i=0x80;i>0;i/=2) //shift bit for masking
{ if (i & value) {
DATA(1); // TRISCbits.RC5 = 1; //masking value with i , write to SENSI-BUS
} else {
DATA(0); //PORTCbits.RC5 = 0; TRISCbits.RC5 = 0;
}
Delay10TCYx(2*sht_speed);
SCK(1); //clk for SENSI-BUS
Delay10TCYx(2*sht_speed);
SCK(0);
Delay10TCYx(2*sht_speed);
}
DATA(1); //TRISCbits.RC5 = 1; //release DATA-line
Delay10TCYx(2*sht_speed);
SCK(1); //clk #9 for ack
Delay10TCYx(2*sht_speed);
error=DATA_IN; //check ack (DATA will be pulled down by SHT11)
SCK(0);
Delay10TCYx(2*sht_speed);
return error; //error=1 in case of no acknowledge
}
//----------------------------------------------------------------------------------
char sht_read_byte(unsigned char ack)
//----------------------------------------------------------------------------------
// reads a byte form the Sensibus and gives an acknowledge in case of "ack=1"
{
unsigned char i,val=0;
DATA(1);//TRISCbits.RC5 = 1; //release DATA-line
for (i=0x80;i>0;i/=2) //shift bit for masking
{
SCK(1); //clk for SENSI-BUS
Delay10TCYx(2*sht_speed);
if (DATA_IN) val=(val | i); //read bit
SCK(0);
Delay10TCYx(sht_speed);
}
if (ack){
DATA(0); //PORTCbits.RC5 = 0; TRISCbits.RC5 = 0;
} else {
DATA(1); //TRISCbits.RC5 = 1;
}
//in case of "ack==1" pull down DATA-Line
SCK(1); //clk #9 for ack
Delay10TCYx(2*sht_speed);
SCK(0); //release DATA-line
DATA(1);//TRISCbits.RC5 = 1;
return val;
}
//----------------------------------------------------------------------------------
void sht_connectionreset(void)
//----------------------------------------------------------------------------------
// communication reset: DATA-line=1 and at least 9 SCK cycles followed by transstart
// _____________________________________________________ ________
// DATA: |_______|
// _ _ _ _ _ _ _ _ _ ___ ___
// SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______| |___| |______
{
unsigned char i;
DATA(1);//TRISCbits.RC5 = 1;
Delay10TCYx(2*sht_speed);
SCK(0); //Initial state
Delay10TCYx(2*sht_speed);
for(i=0;i<9;i++) //9 SCK cycles
{ SCK(1);
Delay10TCYx(2*sht_speed);
SCK(0);
Delay10TCYx(2*sht_speed);
}
sht_transstart(); //transmission start
}
/**************************************************
Function: SPI_RW();
Description:
Writes one UINT8 to RFM73, and return the UINT8 read
// **************************************************/
UINT8 SPI_RW(UINT8 inputValue)
{
UINT8 curBit;
UINT8 outputValue = 0x00;
//int i;
for(curBit = 0; curBit < 8; curBit++) // output 8-bit
{
MOSI(inputValue & 0x80);
inputValue *= 2; // shift next bit into MSB..
SCK(1);
outputValue *= 2;
outputValue += MISO;
//LED(MISO);
SCK(0); // ..then set SCK low again
}
return(outputValue); // return read UINT8
}
//----------------------------------------------------------------------------------
void sht_transstart(void)
//----------------------------------------------------------------------------------
// generates a transmission start
// _____ ________
// DATA: |_______|
// ___ ___
// SCK : ___| |___| |______
{
DATA(1);//TRISCbits.RC5 = 1;
SCK(0); //Initial state
Delay10TCYx(2*sht_speed);
SCK(1);
Delay10TCYx(2*sht_speed);
DATA(0);//PORTCbits.RC5 = 0; TRISCbits.RC5 = 0;
Delay10TCYx(2*sht_speed);
SCK(0);
Delay10TCYx(2*sht_speed);
SCK(1);
Delay10TCYx(2*sht_speed);
DATA(1); //TRISCbits.RC5 = 1;
Delay10TCYx(2*sht_speed);
SCK(0);
}
