LM35 series(LM35, LM35A) is a temperatures sensor IC (-55 °C to +150 °C) made by Texas Instruments. This posting will provide the OSS-ECAL(Open Source Software for Electronic Components Abstraction Layer) for LM35 series.
MCU interface : ADC
CAUTION:Please be sure to refer to the latest version of the Datasheet prior to actual design.
LM35 series(LM35, LM35A)
General description
The LM35 series are precision integrated-circuit temperature devices with an output voltage linearly-proportional to the Centigrade temperature. The LM35 device has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from the output to obtain convenient Centigrade scaling. The LM35 device does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full −55°C to 150°C temperature range. Lower cost is assured by trimming and calibration at the wafer level. The low-output impedance, linear output, and precise inherent calibration of the LM35 device makes interfacing to readout or control circuitry especially easy. The device is used with single power supplies, or with plus and minus supplies. As the LM35 device draws only 60 μA from the supply, it has very low self-heating of less than 0.1°C in still air. The LM35 device is rated to operate over a −55°C to 150°C temperature range, while the LM35C device is rated for a −40°C to 110°C range (−10° with improved accuracy). The LM35-series devices are available packaged in hermetic TO transistor packages, while the LM35C, LM35CA, and LM35D devices are available in the plastic TO-92 transistor package. The LM35D device is available in an 8-lead surface-mount small-outline package and a plastic TO-220 package.
Feature
- Calibrated Directly in Celsius (Centigrade)
- Linear + 10-mV/°C Scale Factor
- 0.5°C Ensured Accuracy (at 25°C)
- Rated for Full −55°C to 150°C Range
- Suitable for Remote Applications
- Low-Cost Due to Wafer-Level Trimming
- Operates From 4 V to 30 V
- Less Than 60-μA Current Drain
- Low Self-Heating, 0.08°C in Still Air
- Non-Linearity Only ±¼°C Typical
- Low-Impedance Output, 0.1 Ω for 1-mA Load
Application
- Power Supplies
- Battery Management
- HVAC
- Appliances
OSS-ECAL specification
API Function
etSTS oLM35( etCMD cmd, float32* rlt )
The oLM35 function is an API function that executes LM35 series(LM35, LM35A) processing according to the command in the argument.
| Return value | etSTS | OSS-ECAL status code | |
| eSTS_FIN | Completed successfully | ||
| eSTS_ERR_MIN | Minimum temperature error (rlt is minimum temperature) | ||
| eSTS_ERR_MAX | Maximum temperature error (rlt is maximum temperature) | ||
| eSTS_ERR_HAL_ADC | HAL ADC Error | ||
| eSTS_ERR_COMMAND_CODE | Command selection error | ||
| eSTS_ERR_OTHERS_RUN | Other components are executing the process | ||
| eSTS_ERR_HAL_OTHERS_RUN | Other application is running HAL | ||
| eSTS_ERR_ADC_OBJECT | AD conversion object selection error | ||
| Parameter IN | etCMD cmd | OSS-ECAL command code | |
| eCMD_START | Command to start AD conversion. | ||
| eCMD_READ | Command that reads the AD conversion value, converts the AD conversion value to a characteristic Temperature, and stores the Temperature in rlt. AD conversion value to temperature conversion equation Voltage value = (AD conversion value × VDD) / ( 2AD bit ) Temperature = ((voltage value – voltage offset value) / gain) + Temperature offset value (Min, Max Limit) | ||
| eCMD_START_READ | Command that starts AD conversion, waits for AD conversion to finish, reads out the AD conversion value, converts the AD conversion value to a characteristic Temperature, and stores the Temperature in rlt. AD conversion value to temperature conversion equation Voltage value = (AD conversion value × VDD) / ( 2AD bit ) Temperature = ((voltage value – voltage offset value) / gain) + Temperature offset value (Min, Max Limit) | ||
| Parameter OUT | float32* rlt | Temperature -55.0 to +150.0 [°C] |
Command Correspondence Table by HAL
| Arduino | eCMD_START_READ |
| ARM Mbed | eCMD_START_READ |
| Debian(Linux) | eCMD_START_READ |
| Infineon ModusToolbox | eCMD_START_READ |
| NXP MCUXpresso iMXRT1051B_1052B | eCMD_START eCMD_READ eCMD_START_READ |
| Renesas SSP | eCMD_START eCMD_READ eCMD_START_READ |
| STM STM32Cube FW_F4 | eCMD_START eCMD_READ eCMD_START_READ |
etSTS oLM35_START(void)
The oLM35_START function is an API function to start AD conversion of the LM35 series(LM35, LM35A).
| Return value | etSTS | OSS-ECAL status code | |
| eSTS_FIN | Completed successfully | ||
| eSTS_ERR_HAL_ADC | HAL ADC Error | ||
| eSTS_ERR_OTHERS_RUN | Other components are executing the process | ||
| eSTS_ERR_HAL_OTHERS_RUN | Other application is running HAL | ||
| eSTS_ERR_ADC_OBJECT | AD conversion object selection error |
Function Correspondence Table by HAL
| Arduino | – |
| ARM Mbed | – |
| Debian(Linux) | – |
| Infineon ModusToolbox | – |
| NXP MCUXpresso iMXRT1051B_1052B | X |
| Renesas SSP | X |
| STM STM32Cube FW_F4 | X |
etSTS oLM35_READ( float32* rlt )
The oLM35_READ function is an API function that checks for the end of AD conversion of the LM35 series(LM35, LM35A), reads the AD conversion value, converts the AD conversion value to a characteristic temperature, and stores the temperature in rlt.
AD conversion value to temperature conversion equation
Voltage value = (AD conversion value × VDD) / ( 2AD bit )
Temperature = ((voltage value – voltage offset value) / gain) + Temperature offset value (Min, Max Limit)
| Return value | etSTS | OSS-ECAL status code | |
| eSTS_FIN | Completed successfully | ||
| eSTS_ERR_MIN | Minimum temperature error (rlt is minimum temperature) | ||
| eSTS_ERR_MAX | Maximum temperature error (rlt is maximum temperature) | ||
| eSTS_ERR_HAL_ADC | HAL ADC Error | ||
| eSTS_ERR_TIMEOUT | ADC Timeout error (AUTOSAR only) | ||
| eSTS_ERR_OTHERS_RUN | Other components are executing the process | ||
| eSTS_ERR_ADC_OBJECT | AD conversion object selection error | ||
| Parameter OUT | float32* rlt | Temperature -55.0 to +150.0 [°C] |
Function Correspondence Table by HAL
| Arduino | – | |
| ARM Mbed | – | |
| Debian(Linux) | – | |
| Infineon ModusToolbox | – | |
| NXP MCUXpresso iMXRT1051B_1052B | X | |
| Renesas SSP | X | |
| STM STM32Cube FW_F4 | X | Time-out time HAL_MAX_DELAY |
etSTS oLM35_START_READ( float32* rlt )
The oLM35_START_READ function is an API function that starts an AD conversion of the LM35 series(LM35, LM35A), waits for the AD conversion to finish, reads the AD conversion value, converts the AD conversion value to a temperature characteristic, and stores the temperature in rlt.
AD conversion value to temperature conversion equation
Voltage value = (AD conversion value × VDD) / ( 2AD bit )
Temperature = ((voltage value – voltage offset value) / gain) + Temperature offset value (Min, Max Limit)
| Return value | etSTS | OSS-ECAL status code | |
| eSTS_FIN | Completed successfully | ||
| eSTS_ERR_MIN | Minimum temperature error (rlt is minimum temperature) | ||
| eSTS_ERR_MAX | Maximum temperature error (rlt is maximum temperature) | ||
| eSTS_ERR_HAL_ADC | HAL ADC Error | ||
| eSTS_ERR_OTHERS_RUN | Other components are executing the process | ||
| eSTS_ERR_HAL_OTHERS_RUN | Other application is running HAL | ||
| eSTS_ERR_ADC_OBJECT | AD conversion object selection error | ||
| Parameter OUT | float32* rlt | Temperature -55.0 to +150.0 [°C] |
Function Correspondence Table by HAL
| Arduino | X | |
| ARM Mbed | X | |
| Debian(Linux) | X | |
| Infineon ModusToolbox | X | |
| NXP MCUXpresso iMXRT1051B_1052B | X | |
| Renesas SSP | X | |
| STM STM32Cube FW_F4 | X | Time-out time HAL_MAX_DELAY |
Files
| Folder* | File | Summary |
|---|---|---|
| LM35_HALNAME_VERSION/sample | sample.c (.cpp) | Sample Application Program |
| sample.h | Sample Application Header | |
| LM35_HALNAME_VERSION | oLM35.c (.cpp) | OSS-ECAL Program for LM35 series(LM35, LM35A) |
| oLM35.h | OSS-ECAL Header for LM35 series(LM35, LM35A) | |
| LM35_ARDUINO.ino | Sample application programs for Arduino | |
| oss_ecal.h | OSS-ECAL Common Header (Ver 01.00.00 or later) | |
| user_setting.c (.cpp) | Const and Table of User setting | |
| user_setting.h | Header of User setting | |
| readme.md | Readme | |
| OSS-ECAL Terms of Use.txt | OSS-ECAL Terms of Use |
* For HALNAME, please refer to HAL Support.
HAL Support List
| HAL | MCU* | Development environment* | HALNAME |
|---|---|---|---|
| Arduino 1.8.6 | ATmega2560 ATmega328P | Mega 2560 Rev3 Arduino Pro Mini 3.3V | ARDUINO |
| ARM Mbed 6.17.0 | STM32F401RE | STM32 Nucleo-64 boards | MBED |
| Infineon ModusToolbox HAL Cat1 2.4.3 | CYBLE-416045-02 | CY8CPROTO-063-BLE PSoC 6 BLE Prototyping Kit | ModusToolbox |
| NXP MCUXpresso SDK iMXRT1051B_1052B ksdk2_0 | MIMXRT1052DVL6A | IMXRT1050-EVKB | iMXRT1051B1052B |
| Renesas SSP 2.4.0 | R7FS7G27H3A01CFC | S7G2 SK | SSP |
| STM STM32Cube FW_F4 V1.27.1 | STM32F401RE | STM32 Nucleo-64 boards | STM32F4 |
| Debian(Linux) v2022.04 | TI AM335x | BeagleBone Black – Rev C | Linux |
* MCU and development environment at the time of development. Even if the same HAL is used, different MCUs and development environments may not work together.
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Built-in How to
How to incorporate OSS-ECAL into user programs
How to incorporate multiple OSS-ECALs in a user program (same MCU function)
How to incorporate multiple OSS-ECALs in a user program (different MCU function)
How to incorporate multiple identical electronic components into a user program
How to reduce the impact on user programs by replacing electronic components
CAUTION
The sample version of OSS-ECAL is not intended to be used with Threads (Tasks) or interrupts of different priority. Please do not use it as in the example below.
Example: If each sensor is assigned to the same ADC group and the OSS-ECAL API is executed in processes with different priorities, correct values may not be obtained.
ADC Gr0 Ch0 Temperature sensor AD22100A 100ms cycle Thread (low priority) to take in temperature
ADC Gr0 Ch1 Pressure sensor MPX5999D Event interrupts (high priority) to take pressure