LM50B is a temperatures sensor IC (-25 °C to +100 °C) made by Texas Instruments. This posting will provide the OSS-ECAL(Open Source Software for Electronic Components Abstraction Layer) for LM50B.
MCU interface : ADC
CAUTION:Please be sure to refer to the latest version of the Datasheet prior to actual design.
LM50B
General description
The LM50 and LM50-Q1 devices are precision integrated-circuit temperature sensors that can sense a –40°C to 125°C temperature range using a single positive supply. The output voltage of the device is linearly proportional to temperature (10 mV/°C) and has a DC offset of 500 mV. The offset allows reading negative temperatures without the need for a negative supply.
The ideal output voltage of the LM50 or LM50-Q1 ranges from 100 mV to 1.75 V for a –40°C to 125°C temperature range. The LM50 and LM50-Q1 do not require any external calibration or trimming to provide accuracies of ±3°C at room temperature and ±4°C over the full –40°C to 125°C temperature range. Trimming and calibration of the LM50 and LM50-Q1 at the wafer level assure low cost and high accuracy. The linear output, 500 mV offset, and factory calibration of the LM50 and LM50-Q1 simplify the circuitry requirements in a single supply environment where reading negative temperatures is necessary. Because the quiescent current of the LM50 and LM50-Q1 is less than 130 µA, self-heating is limited to a very low 0.2°C in still air.
Feature
- LM50-Q1 is AEC-Q100 Grade 1 Qualified and is Manufactured on an Automotive Grade Flow
- Calibrated Directly in Degrees Celsius (Centigrade)
- Linear + 10 mV/°C Scale Factor
- ±2°C Accuracy Specified at 25°C
- Specified for Full –40° to 125°C Range
- Suitable for Remote Applications
- Low Cost Due to Wafer-Level Trimming
- Operates From 4.5 V to 10 V
- Less Than 130-µA Current Drain
- Low Self-Heating: Less Than 0.2°C in Still A
- Nonlinearity Less Than 0.8°C Over Temp
- UL Recognized Component
Application
- Automotive
- Computers
- Disk Drives
- Battery Management
- FAX Machines
- Printers
- Portable Medical Instruments
- HVAC
- Power Supply Modules
OSS-ECAL specification
API Function
etSTS oLM50B( etCMD cmd, float32* rlt )
The oLM50B function is an API function that executes LM50B 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 -25.0 to +100.0 [°C] |
Command Correspondence Table by HAL
| Arduino | eCMD_START_READ |
| ARM Mbed | 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 oLM50B_START(void)
The oLM50B_START function is an API function to start AD conversion of the LM50B.
| 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 | – |
| Infineon ModusToolbox | – |
| NXP MCUXpresso iMXRT1051B_1052B | X |
| Renesas SSP | X |
| STM STM32Cube FW_F4 | X |
etSTS oLM50B_READ( float32* rlt )
The oLM50B_READ function is an API function that checks for the end of AD conversion of the LM50B, 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 -25.0 to +100.0 [°C] |
Function Correspondence Table by HAL
| Arduino | – | |
| ARM Mbed | – | |
| Infineon ModusToolbox | – | |
| NXP MCUXpresso iMXRT1051B_1052B | X | |
| Renesas SSP | X | |
| STM STM32Cube FW_F4 | X | Time-out time HAL_MAX_DELAY |
etSTS oLM50B_START_READ( float32* rlt )
The oLM50B_START_READ function is an API function that starts an AD conversion of the LM50B, 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 -25.0 to +100.0 [°C] |
Function Correspondence Table by HAL
| Arduino | X | |
| ARM Mbed | 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 |
|---|---|---|
| LM50B_HALNAME_VERSION/sample | sample.c (.cpp) | Sample Application Program |
| sample.h | Sample Application Header | |
| LM50B_HALNAME_VERSION | oLM50B.c (.cpp) | OSS-ECAL Program for LM50B |
| oLM50B.h | OSS-ECAL Header for LM50B | |
| LM50B_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 |
* 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