丧心病狂省时间，DS18B20 时间转换从750ms到96ms

hi55234 · 发表于 2014-8-22 11:58:42

本帖最后由 hi55234 于 2014-8-31 21:31 编辑

本来嘛，DS18B20是可以通过寄存器R0、R1调节精度的~~~

可哥们那c语言简直是0基础，一看到MOV啥的，那就1一个头2个大~~~

于是乎直接放弃，可750ms的时间真心伤不起啊~~~肿么办？

丧心病狂修改DallasTemperature.cpp

但凡涉及bit数字，的一律改为9，额差不多就这个样子：

// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// Version 3.7.2 modified on Dec 6, 2011 to support Arduino 1.0
// See Includes...
// Modified by Jordan Hochenbaum
#include "DallasTemperature.h"
#if ARDUINO >= 100
#include "Arduino.h"
#else
extern "C" {
#include "WConstants.h"
}
#endif
DallasTemperature::DallasTemperature(OneWire* _oneWire)
#if REQUIRESALARMS
: _AlarmHandler(&defaultAlarmHandler)
#endif
{
_wire = _oneWire;
devices = 0;
parasite = false;
bitResolution = 9;
waitForConversion = true;
checkForConversion = true;
}
// initialise the bus
void DallasTemperature::begin(void)
{
DeviceAddress deviceAddress;
_wire->reset_search();
devices = 0; // Reset the number of devices when we enumerate wire devices
while (_wire->search(deviceAddress))
{
if (validAddress(deviceAddress))
{
if (!parasite && readPowerSupply(deviceAddress)) parasite = true;
ScratchPad scratchPad;
readScratchPad(deviceAddress, scratchPad);
bitResolution = max(bitResolution, getResolution(deviceAddress));
devices++;
}
}
}
// returns the number of devices found on the bus
uint8_t DallasTemperature::getDeviceCount(void)
{
return devices;
}
// returns true if address is valid
bool DallasTemperature::validAddress(const uint8_t* deviceAddress)
{
return (_wire->crc8(deviceAddress, 7) == deviceAddress[7]);
}
// finds an address at a given index on the bus
// returns true if the device was found
bool DallasTemperature::getAddress(uint8_t* deviceAddress, uint8_t index)
{
uint8_t depth = 0;
_wire->reset_search();
while (depth <= index && _wire->search(deviceAddress))
{
if (depth == index && validAddress(deviceAddress)) return true;
depth++;
}
return false;
}
// attempt to determine if the device at the given address is connected to the bus
bool DallasTemperature::isConnected(const uint8_t* deviceAddress)
{
ScratchPad scratchPad;
return isConnected(deviceAddress, scratchPad);
}
// attempt to determine if the device at the given address is connected to the bus
// also allows for updating the read scratchpad
bool DallasTemperature::isConnected(const uint8_t* deviceAddress, uint8_t* scratchPad)
{
readScratchPad(deviceAddress, scratchPad);
return (_wire->crc8(scratchPad, 8) == scratchPad[SCRATCHPAD_CRC]);
}
// read device's scratch pad
void DallasTemperature::readScratchPad(const uint8_t* deviceAddress, uint8_t* scratchPad)
{
// send the command
_wire->reset();
_wire->select(deviceAddress);
_wire->write(READSCRATCH);
// TODO => collect all comments & use simple loop
// byte 0: temperature LSB
// byte 1: temperature MSB
// byte 2: high alarm temp
// byte 3: low alarm temp
// byte 4: DS18S20: store for crc
// DS18B20 & DS1822: configuration register
// byte 5: internal use & crc
// byte 6: DS18S20: COUNT_REMAIN
// DS18B20 & DS1822: store for crc
// byte 7: DS18S20: COUNT_PER_C
// DS18B20 & DS1822: store for crc
// byte 8: SCRATCHPAD_CRC
//
// for(int i=0; i<9; i++)
// {
// scratchPad[i] = _wire->read();
// }
// read the response
// byte 0: temperature LSB
scratchPad[TEMP_LSB] = _wire->read();
// byte 1: temperature MSB
scratchPad[TEMP_MSB] = _wire->read();
// byte 2: high alarm temp
scratchPad[HIGH_ALARM_TEMP] = _wire->read();
// byte 3: low alarm temp
scratchPad[LOW_ALARM_TEMP] = _wire->read();
// byte 4:
// DS18S20: store for crc
// DS18B20 & DS1822: configuration register
scratchPad[CONFIGURATION] = _wire->read();
// byte 5:
// internal use & crc
scratchPad[INTERNAL_BYTE] = _wire->read();
// byte 6:
// DS18S20: COUNT_REMAIN
// DS18B20 & DS1822: store for crc
scratchPad[COUNT_REMAIN] = _wire->read();
// byte 7:
// DS18S20: COUNT_PER_C
// DS18B20 & DS1822: store for crc
scratchPad[COUNT_PER_C] = _wire->read();
// byte 8:
// SCTRACHPAD_CRC
scratchPad[SCRATCHPAD_CRC] = _wire->read();
_wire->reset();
}
// writes device's scratch pad
void DallasTemperature::writeScratchPad(const uint8_t* deviceAddress, const uint8_t* scratchPad)
{
_wire->reset();
_wire->select(deviceAddress);
_wire->write(WRITESCRATCH);
_wire->write(scratchPad[HIGH_ALARM_TEMP]); // high alarm temp
_wire->write(scratchPad[LOW_ALARM_TEMP]); // low alarm temp
// DS1820 and DS18S20 have no configuration register
if (deviceAddress[0] != DS18S20MODEL) _wire->write(scratchPad[CONFIGURATION]); // configuration
_wire->reset();
_wire->select(deviceAddress); //<--this line was missing
// save the newly written values to eeprom
_wire->write(COPYSCRATCH, parasite);
if (parasite) delay(10); // 10ms delay
_wire->reset();
}
// reads the device's power requirements
bool DallasTemperature::readPowerSupply(const uint8_t* deviceAddress)
{
bool ret = false;
_wire->reset();
_wire->select(deviceAddress);
_wire->write(READPOWERSUPPLY);
if (_wire->read_bit() == 0) ret = true;
_wire->reset();
return ret;
}
// set resolution of all devices to 9, 10, 11, or 12 bits
// if new resolution is out of range, it is constrained.
void DallasTemperature::setResolution(uint8_t newResolution)
{
bitResolution = constrain(newResolution, 9, 12);
DeviceAddress deviceAddress;
for (int i=0; i<devices; i++)
{
getAddress(deviceAddress, i);
setResolution(deviceAddress, bitResolution);
}
}
// set resolution of a device to 9, 10, 11, or 12 bits
// if new resolution is out of range, 9 bits is used.
bool DallasTemperature::setResolution(const uint8_t* deviceAddress, uint8_t newResolution)
{
ScratchPad scratchPad;
if (isConnected(deviceAddress, scratchPad))
{
// DS1820 and DS18S20 have no resolution configuration register
if (deviceAddress[0] != DS18S20MODEL)
{
switch (newResolution)
{
case 12:
scratchPad[CONFIGURATION] = TEMP_9_BIT;
break;
case 11:
scratchPad[CONFIGURATION] = TEMP_9_BIT;
break;
case 10:
scratchPad[CONFIGURATION] = TEMP_9_BIT;
break;
case 9:
default:
scratchPad[CONFIGURATION] = TEMP_9_BIT;
break;
}
writeScratchPad(deviceAddress, scratchPad);
}
return true; // new value set
}
return false;
}
// returns the global resolution
uint8_t DallasTemperature::getResolution()
{
return bitResolution;
}
// returns the current resolution of the device, 9-12
// returns 0 if device not found
uint8_t DallasTemperature::getResolution(const uint8_t* deviceAddress)
{
// DS1820 and DS18S20 have no resolution configuration register
if (deviceAddress[0] == DS18S20MODEL) return 9;
ScratchPad scratchPad;
if (isConnected(deviceAddress, scratchPad))
{
switch (scratchPad[CONFIGURATION])
{
case TEMP_12_BIT:
return 9;
case TEMP_11_BIT:
return 9;
case TEMP_10_BIT:
return 9;
case TEMP_9_BIT:
return 9;
}
}
return 0;
}
// sets the value of the waitForConversion flag
// TRUE : function requestTemperature() etc returns when conversion is ready
// FALSE: function requestTemperature() etc returns immediately (USE WITH CARE!!)
// (1) programmer has to check if the needed delay has passed
// (2) but the application can do meaningful things in that time
void DallasTemperature::setWaitForConversion(bool flag)
{
waitForConversion = flag;
}
// gets the value of the waitForConversion flag
bool DallasTemperature::getWaitForConversion()
{
return waitForConversion;
}
// sets the value of the checkForConversion flag
// TRUE : function requestTemperature() etc will 'listen' to an IC to determine whether a conversion is complete
// FALSE: function requestTemperature() etc will wait a set time (worst case scenario) for a conversion to complete
void DallasTemperature::setCheckForConversion(bool flag)
{
checkForConversion = flag;
}
// gets the value of the waitForConversion flag
bool DallasTemperature::getCheckForConversion()
{
return checkForConversion;
}
bool DallasTemperature::isConversionAvailable(const uint8_t* deviceAddress)
{
// Check if the clock has been raised indicating the conversion is complete
ScratchPad scratchPad;
readScratchPad(deviceAddress, scratchPad);
return scratchPad[0];
}
// sends command for all devices on the bus to perform a temperature conversion
void DallasTemperature::requestTemperatures()
{
_wire->reset();
_wire->skip();
_wire->write(STARTCONVO, parasite);
// ASYNC mode?
if (!waitForConversion) return;
blockTillConversionComplete(bitResolution, NULL);
}
// sends command for one device to perform a temperature by address
// returns FALSE if device is disconnected
// returns TRUE otherwise
bool DallasTemperature::requestTemperaturesByAddress(const uint8_t* deviceAddress)
{
_wire->reset();
_wire->select(deviceAddress);
_wire->write(STARTCONVO, parasite);
// check device
ScratchPad scratchPad;
if (!isConnected(deviceAddress, scratchPad)) return false;
// ASYNC mode?
if (!waitForConversion) return true;
blockTillConversionComplete(getResolution(deviceAddress), deviceAddress);
return true;
}
// returns number of milliseconds to wait till conversion is complete (based on IC datasheet)
int16_t DallasTemperature::millisToWaitForConversion(uint8_t bitResolution)
{
switch (bitResolution)
{
case 9:
return 94;
case 10:
return 188;
case 11:
return 375;
default:
return 750;
}
}
// Continue to check if the IC has responded with a temperature
void DallasTemperature::blockTillConversionComplete(uint8_t bitResolution, const uint8_t* deviceAddress)
{
int delms = millisToWaitForConversion(bitResolution);
if (deviceAddress != NULL && checkForConversion && !parasite)
{
unsigned long timend = millis() + delms;
while(!isConversionAvailable(deviceAddress) && (millis() < timend));
}
else
{
delay(delms);
}
}
// sends command for one device to perform a temp conversion by index
bool DallasTemperature::requestTemperaturesByIndex(uint8_t deviceIndex)
{
DeviceAddress deviceAddress;
getAddress(deviceAddress, deviceIndex);
return requestTemperaturesByAddress(deviceAddress);
}
// Fetch temperature for device index
float DallasTemperature::getTempCByIndex(uint8_t deviceIndex)
{
DeviceAddress deviceAddress;
if (!getAddress(deviceAddress, deviceIndex))
return DEVICE_DISCONNECTED_C;
return getTempC((uint8_t*)deviceAddress);
}
// Fetch temperature for device index
float DallasTemperature::getTempFByIndex(uint8_t deviceIndex)
{
DeviceAddress deviceAddress;
if (!getAddress(deviceAddress, deviceIndex))
return DEVICE_DISCONNECTED_F;
return getTempF((uint8_t*)deviceAddress);
}
// reads scratchpad and returns fixed-point temperature, scaling factor 2^-7
int16_t DallasTemperature::calculateTemperature(const uint8_t* deviceAddress, uint8_t* scratchPad)
{
int16_t fpTemperature =
(((int16_t) scratchPad[TEMP_MSB]) << 11) |
(((int16_t) scratchPad[TEMP_LSB]) << 3);
/*
DS1820 and DS18S20 have a 9-bit temperature register.
Resolutions greater than 9-bit can be calculated using the data from
the temperature, and COUNT REMAIN and COUNT PER °C registers in the
scratchpad. The resolution of the calculation depends on the model.
While the COUNT PER °C register is hard-wired to 16 (10h) in a
DS18S20, it changes with temperature in DS1820.
After reading the scratchpad, the TEMP_READ value is obtained by
truncating the 0.5°C bit (bit 0) from the temperature data. The
extended resolution temperature can then be calculated using the
following equation:
COUNT_PER_C - COUNT_REMAIN
TEMPERATURE = TEMP_READ - 0.25 + --------------------------
COUNT_PER_C
Hagai Shatz simplified this to integer arithmetic for a 12 bits
value for a DS18S20, and James Cameron added legacy DS1820 support.
See - [url]http://myarduinotoy.blogspot.co.uk/2013/02/12bit-result-from-ds18s20.html[/url]
*/
if (deviceAddress[0] == DS18S20MODEL)
fpTemperature = ((fpTemperature & 0xfff0) << 3) - 16 +
(
((scratchPad[COUNT_PER_C] - scratchPad[COUNT_REMAIN]) << 7) /
scratchPad[COUNT_PER_C]
);
return fpTemperature;
}
// returns temperature in 1/128 degrees C or DEVICE_DISCONNECTED_RAW if the
// device's scratch pad cannot be read successfully.
// the numeric value of DEVICE_DISCONNECTED_RAW is defined in
// DallasTemperature.h. It is a large negative number outside the
// operating range of the device
int16_t DallasTemperature::getTemp(const uint8_t* deviceAddress)
{
ScratchPad scratchPad;
if (isConnected(deviceAddress, scratchPad)) return calculateTemperature(deviceAddress, scratchPad);
return DEVICE_DISCONNECTED_RAW;
}
// returns temperature in degrees C or DEVICE_DISCONNECTED_C if the
// device's scratch pad cannot be read successfully.
// the numeric value of DEVICE_DISCONNECTED_C is defined in
// DallasTemperature.h. It is a large negative number outside the
// operating range of the device
float DallasTemperature::getTempC(const uint8_t* deviceAddress)
{
return rawToCelsius(getTemp(deviceAddress));
}
// returns temperature in degrees F or DEVICE_DISCONNECTED_F if the
// device's scratch pad cannot be read successfully.
// the numeric value of DEVICE_DISCONNECTED_F is defined in
// DallasTemperature.h. It is a large negative number outside the
// operating range of the device
float DallasTemperature::getTempF(const uint8_t* deviceAddress)
{
return rawToFahrenheit(getTemp(deviceAddress));
}
// returns true if the bus requires parasite power
bool DallasTemperature::isParasitePowerMode(void)
{
return parasite;
}
#if REQUIRESALARMS
/*
ALARMS:
TH and TL Register Format
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
S 2^6 2^5 2^4 2^3 2^2 2^1 2^0
Only bits 11 through 4 of the temperature register are used
in the TH and TL comparison since TH and TL are 8-bit
registers. If the measured temperature is lower than or equal
to TL or higher than or equal to TH, an alarm condition exists
and an alarm flag is set inside the DS18B20. This flag is
updated after every temperature measurement; therefore, if the
alarm condition goes away, the flag will be turned off after
the next temperature conversion.
*/
// sets the high alarm temperature for a device in degrees Celsius
// accepts a float, but the alarm resolution will ignore anything
// after a decimal point. valid range is -55C - 125C
void DallasTemperature::setHighAlarmTemp(const uint8_t* deviceAddress, char celsius)
{
// make sure the alarm temperature is within the device's range
if (celsius > 125) celsius = 125;
else if (celsius < -55) celsius = -55;
ScratchPad scratchPad;
if (isConnected(deviceAddress, scratchPad))
{
scratchPad[HIGH_ALARM_TEMP] = (uint8_t)celsius;
writeScratchPad(deviceAddress, scratchPad);
}
}
// sets the low alarm temperature for a device in degrees Celsius
// accepts a float, but the alarm resolution will ignore anything
// after a decimal point. valid range is -55C - 125C
void DallasTemperature::setLowAlarmTemp(const uint8_t* deviceAddress, char celsius)
{
// make sure the alarm temperature is within the device's range
if (celsius > 125) celsius = 125;
else if (celsius < -55) celsius = -55;
ScratchPad scratchPad;
if (isConnected(deviceAddress, scratchPad))
{
scratchPad[LOW_ALARM_TEMP] = (uint8_t)celsius;
writeScratchPad(deviceAddress, scratchPad);
}
}
// returns a char with the current high alarm temperature or
// DEVICE_DISCONNECTED for an address
char DallasTemperature::getHighAlarmTemp(const uint8_t* deviceAddress)
{
ScratchPad scratchPad;
if (isConnected(deviceAddress, scratchPad)) return (char)scratchPad[HIGH_ALARM_TEMP];
return DEVICE_DISCONNECTED_C;
}
// returns a char with the current low alarm temperature or
// DEVICE_DISCONNECTED for an address
char DallasTemperature::getLowAlarmTemp(const uint8_t* deviceAddress)
{
ScratchPad scratchPad;
if (isConnected(deviceAddress, scratchPad)) return (char)scratchPad[LOW_ALARM_TEMP];
return DEVICE_DISCONNECTED_C;
}
// resets internal variables used for the alarm search
void DallasTemperature::resetAlarmSearch()
{
alarmSearchJunction = -1;
alarmSearchExhausted = 0;
for(uint8_t i = 0; i < 7; i++)
alarmSearchAddress[i] = 0;
}
// This is a modified version of the OneWire::search method.
//
// Also added the OneWire search fix documented here:
// [url]http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238032295[/url]
//
// Perform an alarm search. If this function returns a '1' then it has
// enumerated the next device and you may retrieve the ROM from the
// OneWire::address variable. If there are no devices, no further
// devices, or something horrible happens in the middle of the
// enumeration then a 0 is returned. If a new device is found then
// its address is copied to newAddr. Use
// DallasTemperature::resetAlarmSearch() to start over.
bool DallasTemperature::alarmSearch(uint8_t* newAddr)
{
uint8_t i;
char lastJunction = -1;
uint8_t done = 1;
if (alarmSearchExhausted) return false;
if (!_wire->reset()) return false;
// send the alarm search command
_wire->write(0xEC, 0);
for(i = 0; i < 64; i++)
{
uint8_t a = _wire->read_bit( );
uint8_t nota = _wire->read_bit( );
uint8_t ibyte = i / 8;
uint8_t ibit = 1 << (i & 7);
// I don't think this should happen, this means nothing responded, but maybe if
// something vanishes during the search it will come up.
if (a && nota) return false;
if (!a && !nota)
{
if (i == alarmSearchJunction)
{
// this is our time to decide differently, we went zero last time, go one.
a = 1;
alarmSearchJunction = lastJunction;
}
else if (i < alarmSearchJunction)
{
// take whatever we took last time, look in address
if (alarmSearchAddress[ibyte] & ibit) a = 1;
else
{
// Only 0s count as pending junctions, we've already exhausted the 0 side of 1s
a = 0;
done = 0;
lastJunction = i;
}
}
else
{
// we are blazing new tree, take the 0
a = 0;
alarmSearchJunction = i;
done = 0;
}
// OneWire search fix
// See: [url]http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1238032295[/url]
}
if (a) alarmSearchAddress[ibyte] |= ibit;
else alarmSearchAddress[ibyte] &= ~ibit;
_wire->write_bit(a);
}
if (done) alarmSearchExhausted = 1;
for (i = 0; i < 8; i++) newAddr[i] = alarmSearchAddress[i];
return true;
}
// returns true if device address might have an alarm condition
// (only an alarm search can verify this)
bool DallasTemperature::hasAlarm(const uint8_t* deviceAddress)
{
ScratchPad scratchPad;
if (isConnected(deviceAddress, scratchPad))
{
char temp = calculateTemperature(deviceAddress, scratchPad) >> 7;
// check low alarm
if (temp <= (char)scratchPad[LOW_ALARM_TEMP]) return true;
// check high alarm
if (temp >= (char)scratchPad[HIGH_ALARM_TEMP]) return true;
}
// no alarm
return false;
}
// returns true if any device is reporting an alarm condition on the bus
bool DallasTemperature::hasAlarm(void)
{
DeviceAddress deviceAddress;
resetAlarmSearch();
return alarmSearch(deviceAddress);
}
// runs the alarm handler for all devices returned by alarmSearch()
void DallasTemperature::processAlarms(void)
{
resetAlarmSearch();
DeviceAddress alarmAddr;
while (alarmSearch(alarmAddr))
{
if (validAddress(alarmAddr))
_AlarmHandler(alarmAddr);
}
}
// sets the alarm handler
void DallasTemperature::setAlarmHandler(AlarmHandler *handler)
{
_AlarmHandler = handler;
}
// The default alarm handler
void DallasTemperature::defaultAlarmHandler(const uint8_t* deviceAddress)
{
}
#endif
// Convert float Celsius to Fahrenheit
float DallasTemperature::toFahrenheit(float celsius)
{
return (celsius * 1.8) + 32;
}
// Convert float Fahrenheit to Celsius
float DallasTemperature::toCelsius(float fahrenheit)
{
return (fahrenheit - 32) * 0.555555556;
}
// convert from raw to Celsius
float DallasTemperature::rawToCelsius(int16_t raw)
{
if (raw <= DEVICE_DISCONNECTED_RAW)
return DEVICE_DISCONNECTED_C;
// C = RAW/128
return (float)raw * 0.0078125;
}
// convert from raw to Fahrenheit
float DallasTemperature::rawToFahrenheit(int16_t raw)
{
if (raw <= DEVICE_DISCONNECTED_RAW)
return DEVICE_DISCONNECTED_F;
// C = RAW/128
// F = (C*1.8)+32 = (RAW/128*1.8)+32 = (RAW*0.0140625)+32
return ((float)raw * 0.0140625) + 32;
}
#if REQUIRESNEW
// MnetCS - Allocates memory for DallasTemperature. Allows us to instance a new object
void* DallasTemperature::operator new(unsigned int size) // Implicit NSS obj size
{
void * p; // void pointer
p = malloc(size); // Allocate memory
memset((DallasTemperature*)p,0,size); // Initialise memory
//!!! CANT EXPLICITLY CALL CONSTRUCTOR - workaround by using an init() methodR - workaround by using an init() method
return (DallasTemperature*) p; // Cast blank region to NSS pointer
}
// MnetCS 2009 - Free the memory used by this instance
void DallasTemperature::operator delete(void* p)
{
DallasTemperature* pNss = (DallasTemperature*) p; // Cast to NSS pointer
pNss->~DallasTemperature(); // Destruct the object
free(p); // Free the memory
}
#endif

复制代码

于是乎，实际效果用代码检测：

#include <OneWire.h>
#include <DallasTemperature.h>
// 数字接口10
#define ONE_WIRE_BUS 10
// Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)
OneWire oneWire(ONE_WIRE_BUS);
// Pass our oneWire reference to Dallas Temperature.
DallasTemperature sensors(&oneWire);
unsigned long time2;
void setup(void)
{
// start serial port
Serial.begin(9600);
Serial.println("Dallas Temperature IC Control Library Demo");
// Start up the library
sensors.begin(); // IC Default 9 bit. If you have troubles consider upping it 12. Ups the delay giving the IC more time to process the temperature measurement
}
void loop(void)
{
time2=millis();
sensors.requestTemperatures(); // Send the command to get temperatures
time2=millis()-time2;
Serial.print("Temperature for Device 1 is: ");
Serial.println(sensors.getTempCByIndex(0)); // Why "byIndex"? You can have more than one IC on the same bus. 0 refers to the first IC on the wire
Serial.print("time2 is: ");
Serial.println(time2); // Why "byIndex"? You can have more than one IC on the same bus. 0 refers to the first IC on the wire
delay(1000);
}

复制代码

注意time2的效果.PNG

wing · 发表于 2014-8-22 12:20:38

感觉上你操作寄存器后,
性能有所提升,
但是我没看出那里是修改的关键..................

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丧心病狂省时间，DS18B20 时间转换从750ms到96ms

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