2017-03-28 12:39:11 +02:00
/* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation , either version 3 of the License , or
* ( at your option ) any later version .
*
* This program is distributed in the hope that it will be useful ,
* but WITHOUT ANY WARRANTY ; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE . See the
* GNU General Public License for more details .
*
* You should have received a copy of the GNU General Public License
* along with this program . If not , see < http : //www.gnu.org/licenses/>.
*
*/
/** library for Maxim DS18B20 digital temperature sensor (using 1-Wire protocol) (code)
* @ file sensor_ds18b20 . c
* @ author King Kévin < kingkevin @ cuvoodoo . info >
* @ date 2017
* @ note peripherals used : 1 - Wire ( timer @ ref onewire_master_timer , GPIO @ ref onewire_master_gpio )
* @ warning this library does not support parasite power mode and alarms
*/
/* standard libraries */
# include <stdint.h> // standard integer types
# include <stdbool.h> // boolean type
# include <stdlib.h> // size_t definition
# include <math.h> // NAN definition
/* own libraries */
# include "global.h" // help macros
# include "onewire_master.h" // 1-Wire utilities
# include "sensor_ds18b20.h" // own definitions
/** remember number of DS18B20 sensors on 1-Wire bus for certain functions */
uint64_t sensors = 0 ;
/** remember if only DS18B20 sensors on 1-Wire bus for certain functions */
bool only = false ;
/** remember code of last sensor **/
uint64_t last = 0 ;
void sensor_ds18b20_setup ( void )
{
onewire_master_setup ( ) ; // setup 1-Wire peripheral to communicate with sensors on bus
sensor_ds18b20_number ( ) ; // scan for sensor (remembers sensor number and exclusivity)
}
uint64_t sensor_ds18b20_number ( void )
{
sensors = 0 ; // reset number
only = true ; // reset state
uint64_t code = 0 ; // ROM code found (use 0 to start from scratch)
bool more = true ; // save if other additional slaves exist
while ( more ) { // scan for all 1-Wire slaves
if ( ! onewire_master_reset ( ) ) { // send reset to start communication
return 0 ; // no slave presence detected
}
more = onewire_master_rom_search ( & code , false ) ; // get next slave ROM code (without alarm)
if ( 0 = = code ) { // error occurred
return 0 ;
}
if ( 0x28 = = ( code & 0xff ) ) { // family code (8-LSb) for DS18B20 sensors is 0x28
last = code ; // save last found code
sensors + + ; // we found an additional sensor
} else {
only = false ; // we found a slave which is not a sensor
}
}
return sensors ;
}
bool sensor_ds18b20_only ( void )
{
sensor_ds18b20_number ( ) ; // this also checks for exclusivity
return only ;
}
bool sensor_ds18b20_list ( uint64_t * code )
{
if ( ! onewire_master_reset ( ) ) { // send reset to start communication
return false ; // no slave presence detected
}
onewire_master_rom_search ( code , false ) ; // get next code
return ( last ! = * code ) ; // verify if the last has been found
}
bool sensor_ds18b20_convert ( uint64_t code )
{
if ( 0 = = code & & ! only ) { // asked for broadcast but there are different slaves on bus
return false ; // broadcast not possible when there are also different slaves on bus
}
// send reset pulse
if ( ! onewire_master_reset ( ) ) { // send reset to start communication
return false ; // no slave presence detected
}
// send ROM command to select slave(s)
if ( 0 = = code ) { // broadcast convert
if ( ! onewire_master_rom_skip ( ) ) { // select all slaves
return false ; // ROM command failed
}
} else {
if ( ! onewire_master_rom_match ( code ) ) { // select specific slave
return false ; // ROM command failed
}
}
// send convert T function command
return onewire_master_function_read ( 0x44 , NULL , 0 ) ;
}
float sensor_ds18b20_temperature ( uint64_t code )
{
if ( 0 = = code & & ( sensors > 1 | | ! only ) ) { // broadcast read requested
return NAN ; // this function is not possible when several sensors or other devices are present
}
// send reset pulse
if ( ! onewire_master_reset ( ) ) { // send reset to start communication
return NAN ; // no slave presence detected
}
// send ROM command to select slave
if ( ! onewire_master_rom_match ( code ) ) { // select specific slave
return NAN ; // ROM command failed
}
// read scratchpad to get temperature (on byte 0 and 1)
uint8_t scratchpad [ 9 ] = { 0 } ; // to store read scratchpad
if ( ! onewire_master_function_read ( 0xbe , scratchpad , sizeof ( scratchpad ) * 8 ) ) { // read complete scratchpad
return NAN ; // error occurred during read
}
// verify if data is valid
if ( onewire_master_crc ( scratchpad , sizeof ( scratchpad ) ) ) { // check CRC checksum
return NAN ; // data corrupted
}
// calculate temperature (stored as int16_t but on 0.125 C steps)
return ( ( int16_t ) ( scratchpad [ 1 ] < < 8 ) + scratchpad [ 0 ] ) / 16.0 ; // get temperature (on < 16 precision the last bits are undefined, but that doesn't matter for the end result since the lower precision is still provided)
}
bool sensor_ds18b20_precision ( uint64_t code , uint8_t precision )
{
if ( precision < 9 | | precision > 12 ) { // check input
return false ; // wrong precision value
}
if ( 0 = = code & & ! only ) { // asked for broadcast but there are different slaves on bus
return false ; // broadcast not possible when there are also different slaves on bus
}
// send reset pulse
if ( ! onewire_master_reset ( ) ) { // send reset to start communication
return false ; // no slave presence detected
}
// send ROM command to select slave(s)
if ( 0 = = code ) { // broadcast convert
if ( ! onewire_master_rom_skip ( ) ) { // select all slaves
return false ; // ROM command failed
}
} else {
if ( ! onewire_master_rom_match ( code ) ) { // select specific slave
return false ; // ROM command failed
}
}
// read scratchpad to get alarm values (on byte 2 and 3)
uint8_t scratchpad [ 9 ] = { 0 } ; // to store read scratchpad
if ( ! onewire_master_function_read ( 0xbe , scratchpad , sizeof ( scratchpad ) * 8 ) ) { // read complete scratchpad
return false ; // error occurred during read
}
// verify if data is valid
if ( onewire_master_crc ( scratchpad , sizeof ( scratchpad ) ) ) { // check CRC checksum
return false ; // data corrupted
}
// send new configuration (and keep the alarm values)
2019-03-26 19:27:40 +01:00
uint8_t configuration [ 3 ] = { 0 } ; // to store T_HIGH, T_LOW, and configuration
2017-03-28 12:39:11 +02:00
configuration [ 0 ] = scratchpad [ 2 ] ; // keep T_HIGH
configuration [ 1 ] = scratchpad [ 3 ] ; // keep T_LOW
configuration [ 2 ] = 0x1f + ( ( precision - 9 ) < < 5 ) ; // set precision bit (R1-R0 on bit 6-5)
if ( ! onewire_master_function_write ( 0x4e , configuration , sizeof ( configuration ) * 8 ) ) { // write scratchpad with new configuration (all three bytes must be written)
return false ; // error occurred during write
}
// store new configuration into sensor's EEPROM for retrieval on next power up
if ( ! onewire_master_function_read ( 0x48 , NULL , 0 ) ) { // copy scratchpad (to EEPROM)
return false ; // error during copy
}
return true ;
}