// see http://www.maxim-ic.com/app-notes/index.mvp/id/162
uint8_t ow_reset(void)
{
uint8_t err;
OW_DIR_OUT_LOW(); // pull OW-Pin low for 480us
ow_delay_us(233); // min 480us in total
ow_delay_us(233);
// set Pin as input - wait for clients to pull low
OW_DIR_IN(); // input and pull up
ow_delay_us(53); // 60 us
err = ow_input_pin_state(); // devices should now pull low
// nobody pulled to low, still high-> error
// after a delay the clients should release the line
// and input-pin gets back to high due to pull-up-resistor
ow_delay_us(233); // max 240us in total
if (err==1){
return(1); // no presence puls
}
if( ow_input_pin_state() == 0 ) // short circuit
return(1);
return(0);
}
/* start measurement (CONVERT_T) for all sensors if input id==NULL
or for single sensor. then id is the rom-code */
uint8_t DS18X20_start_meas( uint8_t with_power_extern, uint8_t id[])
{
ow_reset(); //**
if( ow_input_pin_state() ) { // only send if bus is "idle" = high
ow_command( DS18X20_CONVERT_T, id );
if (with_power_extern != DS18X20_POWER_EXTERN)
ow_parasite_enable();
return DS18X20_OK;
}
else {
return DS18X20_START_FAIL;
}
}
uint8_t DS18X20_read_scratchpad( uint8_t id[], uint8_t sp[] )
{
uint8_t i;
ow_reset(); //**
if( ow_input_pin_state() ) { // only send if bus is "idle" = high
ow_command( DS18X20_READ, id );
for ( i=0 ; i< DS18X20_SP_SIZE; i++ ) sp[i]=ow_byte_rd();
return DS18X20_OK;
}
else {
return DS18X20_ERROR;
}
}
/* start measurement (CONVERT_T) for all sensors if input id==NULL
or for single sensor. then id is the rom-code */
uint8_t DS18X20_start_meas(uint8_t with_power_extern, uint8_t id[])
{
ow_reset(); //**
if (ow_input_pin_state()) { // only send if bus is "idle" = high
ow_command(DS18X20_CONVERT_T, id);
if (with_power_extern != DS18X20_POWER_EXTERN)
ow_parasite_enable();
return DS18X20_OK;
} else {
#ifdef DS18X20_VERBOSE
printf_P(PSTR("DS18X20_start_meas: Short Circuit !\r"));
#endif
return DS18X20_START_FAIL;
}
}
uint8_t ow_bit_io( uint8_t b )
{
OW_DIR_OUT_LOW(); // drive bus low
ow_delay_us(1); // Recovery-Time
if ( b ) {
OW_DIR_IN(); // if bit is 1 set bus high (by ext. pull-up)
}
// wuffwuff delay was 15uS-1 see comment above
ow_delay_us(7);
b=ow_input_pin_state();
ow_delay_us(50);
OW_DIR_IN();
return b;
}
uint8_t DS18X20_recall_E2( uint8_t id[] )
{
ow_reset(); //**
if( ow_input_pin_state() ) { // only send if bus is "idle" = high
ow_command( DS18X20_RECALL_E2, id );
// TODO: wait until status is "1" (then eeprom values
// have been copied). here simple delay to avoid timeout
// handling
_delay_ms(10);
return DS18X20_OK;
}
else {
return DS18X20_ERROR;
}
}
uint8_t DS18X20_write_scratchpad( uint8_t id[],
uint8_t th, uint8_t tl, uint8_t conf)
{
ow_reset(); //**
if( ow_input_pin_state() ) { // only send if bus is "idle" = high
ow_command( DS18X20_WRITE_SCRATCHPAD, id );
ow_byte_wr(th);
ow_byte_wr(tl);
if (id[0] == DS18B20_ID) ow_byte_wr(conf); // config avail. on B20 only
return DS18X20_OK;
}
else {
return DS18X20_ERROR;
}
}
uint8_t DS18X20_read_scratchpad(uint8_t id[], uint8_t sp[])
{
uint8_t i;
ow_reset(); //**
if (ow_input_pin_state()) { // only send if bus is "idle" = high
ow_command(DS18X20_READ, id);
for (i = 0 ; i < DS18X20_SP_SIZE; i++) sp[i] = ow_byte_rd();
return DS18X20_OK;
} else {
#ifdef DS18X20_VERBOSE
printf_P(PSTR("DS18X20_read_scratchpad: Short Circuit !\r"));
#endif
return DS18X20_ERROR;
}
}
uint8_t DS18X20_recall_E2(uint8_t id[])
{
ow_reset(); //**
if (ow_input_pin_state()) { // only send if bus is "idle" = high
ow_command(DS18X20_RECALL_E2, id);
// TODO: wait until status is "1" (then eeprom values
// have been copied). here simple delay to avoid timeout
// handling
_delay_ms(DS18X20_COPYSP_DELAY);
return DS18X20_OK;
} else {
#ifdef DS18X20_VERBOSE
printf_P(PSTR("DS18X20_recall_E2: Short Circuit !\r"));
#endif
return DS18X20_ERROR;
}
}
uint8_t DS18X20_write_scratchpad(uint8_t id[],
uint8_t th, uint8_t tl, uint8_t conf)
{
ow_reset(); //**
if (ow_input_pin_state()) { // only send if bus is "idle" = high
ow_command(DS18X20_WRITE_SCRATCHPAD, id);
ow_byte_wr(th);
ow_byte_wr(tl);
if (id[0] == DS18B20_ID) ow_byte_wr(conf); // config avail. on B20 only
return DS18X20_OK;
} else {
#ifdef DS18X20_VERBOSE
printf_P(PSTR("DS18X20_write_scratchpad: Short Circuit !\r"));
#endif
return DS18X20_ERROR;
}
}
uint8_t DS18X20_copy_scratchpad( uint8_t with_power_extern,
uint8_t id[] )
{
ow_reset(); //**
if( ow_input_pin_state() ) { // only send if bus is "idle" = high
ow_command( DS18X20_COPY_SCRATCHPAD, id );
if (with_power_extern != DS18X20_POWER_EXTERN)
ow_parasite_enable();
_delay_ms(10); // wait for 10 ms
if (with_power_extern != DS18X20_POWER_EXTERN)
ow_parasite_disable();
return DS18X20_OK;
}
else {
return DS18X20_START_FAIL;
}
}
uint8_t DS18X20_copy_scratchpad(uint8_t with_power_extern,
uint8_t id[])
{
ow_reset(); //**
if (ow_input_pin_state()) { // only send if bus is "idle" = high
ow_command(DS18X20_COPY_SCRATCHPAD, id);
if (with_power_extern != DS18X20_POWER_EXTERN)
ow_parasite_enable();
_delay_ms(DS18X20_COPYSP_DELAY); // wait for 10 ms
if (with_power_extern != DS18X20_POWER_EXTERN)
ow_parasite_disable();
return DS18X20_OK;
} else {
#ifdef DS18X20_VERBOSE
printf_P(PSTR("DS18X20_copy_scratchpad: Short Circuit !\r"));
#endif
return DS18X20_START_FAIL;
}
}
/* Timing issue when using runtime-bus-selection (!OW_ONE_BUS):
The master should sample at the end of the 15-slot after initiating
the read-time-slot. The variable bus-settings need more
cycles than the constant ones so the delays had to be shortened
to achive a 15uS overall delay
Setting/clearing a bit in I/O Register needs 1 cyle in OW_ONE_BUS
but around 14 cyles in configureable bus (us-Delay is 4 cyles per uS) */
uint8_t ow_bit_io1( uint8_t b )
{
OW_DIR_OUT_LOW(); // drive bus low
ow_delay_us(1); // Recovery-Time 1us
if ( b ) {
OW_DIR_OUT_HIGH();
}else{
OW_DIR_OUT_LOW();
}
ow_delay_us(38);
OW_DIR_IN();
ow_delay_us(2); // Recovery-Time 1us
// wuffwuff delay was 15uS-1 see comment above
OW_DIR_OUT_LOW(); // drive bus low
ow_delay_us(1); // Recovery-Time 1us
OW_DIR_IN();
ow_delay_us(7);
b=ow_input_pin_state();
ow_delay_us(38);
return b;
}
