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Version 1.0.1
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Added internal delays for when an active conversion is still taking place or if one or more parasitic devices are present to prevent data errors or loss.
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Arnd authored Dec 2, 2016
1 parent c7ce686 commit 46d8935
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Showing 2 changed files with 16 additions and 7 deletions.
22 changes: 15 additions & 7 deletions DSFamily.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -100,12 +100,18 @@ boolean DSFamily_Class::Read1WireScratchpad(const uint8_t deviceNumber, //

/*******************************************************************************************************************
** method ReadDeviceTemp() to return the current temperature value for a given device number. All devices except **
** the DS18S20 return raw values in 0.0625°C increments, so the 0.5°C increments of the DS18S20 are converted **
** the DS18S20 return raw values in 0.0625°C increments, so the 0.5°C increments of the DS18S20 are converted to **
** the same scale as the other devices. A check is done to see if there are still conversion(s) being done and a **
** delay is made until any conversions have time to complete. We only store ony value for conversion start time, **
** so the delay might be for another devices and might not be necessary, but the alternative is to store the **
** conversion times for each device which would potentially consume a lot of available memory **
*******************************************************************************************************************/
int16_t DSFamily_Class::ReadDeviceTemp(const uint8_t deviceNumber, // //
const bool raw=false) { // //
uint8_t dsBuffer[9]; // Buffer to hold scratchpad return //
int16_t temperature = DS_BAD_TEMPERATURE; // Holds return value //
if ((_ConvStartTime+ConversionMillis)>millis()) // If a conversion is still running //
delay(millis()-(_ConvStartTime+ConversionMillis)); // then wait until it is finished //
if ( deviceNumber < ThermometersFound && // on a successful read from the //
Read1WireScratchpad(deviceNumber,dsBuffer)) { // device scratchpad //
if (dsBuffer[0]==DS1822_FAMILY) { // The results returned by DS18S20 //
Expand Down Expand Up @@ -338,7 +344,6 @@ float DSFamily_Class::StdDevTemperature(const uint8_t skipDeviceNumber=UINT8_MAX
return(StdDev); // //
} // of method StdDevTemperature //----------------------------------//


/*******************************************************************************************************************
** 1-Wire: Method reset_search(). You need to use this function to start a search again from the beginning. You **
** do not need to do it for the first search, though you could. **
Expand Down Expand Up @@ -555,12 +560,15 @@ uint8_t DSFamily_Class::crc8(const uint8_t *addr, uint8_t len) { //
} // of method crc8() //----------------------------------//

/*******************************************************************************************************************
** Method ParasiticWait(). Wait for any active converstion to complete before doing any 1-Wire actions when one **
** or more devices on the 1-Wire microLAN are using parasitic power **
** Method ParasiticWait(). Any parasitically device needs to have a strong power pullup on the 1-Wire data line **
** during conversion. This means that the whole 1-Wire microLAN is effectively blocked during the rather lengthy **
** conversion time; since using the bus would cause the parasitically powered device to abort conversion. There- **
** this function will wait until the last conversion request has had enough time to complete. The wait time might **
** be unnecessary, but since we only track the last conversion start rather than track each device independently **
** this is the best we can do. **
*******************************************************************************************************************/
void DSFamily_Class::ParasiticWait() { // //
if (Parasitic) { // if we have a parasitic device //
if ((_ConvStartTime+ConversionMillis)>millis()) // if we have to wait for a conver- //
delay(millis()-(_ConvStartTime+ConversionMillis)); // sion to finish then wait //
if (Parasitic && ((_ConvStartTime+ConversionMillis)>millis())) { // If parasitic & active conversion //
delay(millis()-(_ConvStartTime+ConversionMillis)); // then wait until it is finished //
} // of if-then we have a parasitic device on the 1-Wire // //
} // of method ParasiticWait() //----------------------------------//
1 change: 1 addition & 0 deletions DSFamily.h
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Expand Up @@ -51,6 +51,7 @@
** **
** Vers. Date Developer Comments **
** ====== ========== =================== ======================================================================== **
** 1.0.1 2016-12-02 Arnd@SV-Zanshin.Com Added delays for ReadDeviceTemp() and when a parasitic device is present **
** 1.0.0 2016-12-01 Arnd@SV-Zanshin.Com Initial release **
** 1.0.b5 2016-11-30 Arnd@SV-Zanshin.Com Moved 1-Wire calls to private, refactored some of the calls **
** 1.0.b4 2016-11-29 Arnd@SV-Zanshin.Com Included the appropriate sections of the 1-Wire library, see above **
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