Skip to content

Detect power on reset and insufficient power for DS18B20 #289

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
milesburton merged 2 commits into from
Jan 24, 2026
Merged

Detect power on reset and insufficient power for DS18B20 #289

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
41eaac0
fix: filtering fake data from ds18b20
Laxilef Jan 17, 2026
ffc7de9
refactor: added `DEVICE_INSUFFICIENT_POWER_RAW` for insufficient powe…
Laxilef Jan 24, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 9 additions & 0 deletions DallasTemperature.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -558,6 +558,15 @@ int32_t DallasTemperature::calculateTemperature(const uint8_t* deviceAddress, ui
| neg;
}

// detect POR and insufficient power conditions
if (deviceAddress[DSROM_FAMILY] == DS18B20MODEL) {
if (scratchPad[0] == 0x50 && scratchPad[1] == 0x05 && scratchPad[6] == 0x0C) {
return DEVICE_POWER_ON_RESET_RAW;
} else if (scratchPad[0] == 0xFF && scratchPad[1] == 0x07) {
return DEVICE_INSUFFICIENT_POWER_RAW;
}
}

/*
DS1820 and DS18S20 have a 9-bit temperature register.

Expand Down
8 changes: 8 additions & 0 deletions DallasTemperature.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,14 @@
#define DEVICE_FAULT_SHORTVDD_F -421.599976
#define DEVICE_FAULT_SHORTVDD_RAW -32256

#define DEVICE_POWER_ON_RESET_C -251
#define DEVICE_POWER_ON_RESET_F -419.799988
#define DEVICE_POWER_ON_RESET_RAW -32128

#define DEVICE_INSUFFICIENT_POWER_C -250
#define DEVICE_INSUFFICIENT_POWER_F -418.0
#define DEVICE_INSUFFICIENT_POWER_RAW -32000

// Configuration Constants
#define MAX_CONVERSION_TIMEOUT 750
#define MAX_INITIALIZATION_RETRIES 3
Expand Down
6 changes: 6 additions & 0 deletions keywords.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -85,3 +85,9 @@ DEVICE_FAULT_SHORTGND_RAW LITERAL1
DEVICE_FAULT_SHORTVDD_C LITERAL1
DEVICE_FAULT_SHORTVDD_F LITERAL1
DEVICE_FAULT_SHORTVDD_RAW LITERAL1
DEVICE_POWER_ON_RESET_C LITERAL1
DEVICE_POWER_ON_RESET_F LITERAL1
DEVICE_POWER_ON_RESET_RAW LITERAL1
DEVICE_INSUFFICIENT_POWER_C LITERAL1
DEVICE_INSUFFICIENT_POWER_F LITERAL1
DEVICE_INSUFFICIENT_POWER_RAW LITERAL1
8 changes: 8 additions & 0 deletions test/unit_test_001.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,14 @@ unittest(test_error_code) {
assertEqual(DEVICE_FAULT_SHORTVDD_C, -252);
assertEqualFloat(DEVICE_FAULT_SHORTVDD_F, -421.6, 0.1);
assertEqual(DEVICE_FAULT_SHORTVDD_RAW, -32256);

assertEqual(DEVICE_POWER_ON_RESET_C, -251);
assertEqualFloat(DEVICE_POWER_ON_RESET_F, -419.8, 0.1);
assertEqual(DEVICE_POWER_ON_RESET_RAW, -32128);

assertEqual(DEVICE_INSUFFICIENT_POWER_C, -250);
assertEqualFloat(DEVICE_INSUFFICIENT_POWER_F, -418.0, 0.1);
assertEqual(DEVICE_INSUFFICIENT_POWER_RAW, -32000);
}

// Test basic initialization and functionality of the DallasTemperature library
Expand Down