Heat Cost Allocator with wM-Bus at 868 MHz Reference Design


Design files


The TIDA-00838 reference design implements a heat cost allocator system following the EN834 standard with the “two-sensor measurement method". The solution achieves better than 0.5 degrees Celsius accuracy across a range of +20 to +85°C. Two analog temperature sensors are available as matched pairs to eliminate the need for calibration during manufacturing and lowering OEM system cost. Wireless MCU offers wM-Bus support for S-, T- and C-modes (Meter device) at 868MHz and controls the two temperature sensors.

  • Highly accurate temperature sensing across environment conditions: better than 0.5 degrees from +20 to +85°C.
  • CC1310 SimpleLink(TM) Wireless MCU provides single-chip solution for heat measurement and RF communications
  • Sensor Controller interfaces seamlessly to two matched LMT70A, which eliminate the need for calibration during manufacturing and lower OEM system cost
  • Example source code for wM-Bus @868 MHz transmission for S, T and C-modes (“Meter” device) under TI RTOS
  • Cost-optimized 2-layer PCB in HCA form factor and a 96-segments 4-MUX LCD
  • Cap Touch button on the PCB for LCD on/off
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDUB48.PDF (1785 K)

Reference design overview and verified performance test data


Detailed schematic diagram for design layout and components


Complete listing of design components, reference designators, and manufacturers/part numbers


Detailed overview of design layout for component placement


Files used for 3D models or 2D drawings of IC components


Design file that contains information on physical board layer of design PCB

TIDRJR2.PDF (1670 K)

PCB layer plot file used for generating PCB design layout

TIDRJR3.PDF (2218 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Analog temperature sensors

LMT70A±0.1°C Matching Accuracy Precision Analog Temperature Sensor

Data sheet: PDF | HTML
MSP430 microcontrollers

MSP430FR413316 MHz MCU with 16KB FRAM, 2KB SRAM, 10-bit ADC, LCD, UART/SPI/I2C, IR logic, timer

Data sheet: PDF | HTML
Sub-1 GHz wireless MCUs

CC1310SimpleLink™ 32-bit Arm Cortex-M3 Sub-1 GHz wireless MCU with 128kB Flash

Data sheet: PDF | HTML

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Technical documentation

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Type Title Date
* Design guide Heat Cost Allocator With wM-Bus at 868 MHz Design Guide Jan. 21, 2016
Application note Wearable Temp-Sensing Layout Considerations Optimized for Thermal Response (Rev. B) Oct. 23, 2018
White paper RTOS Power Management Emerges as a Key for MCU-based IoT Nodes (Rev. A) May 11, 2017
Technical article Sub-1 GHz + Bluetooth® low energy and low-power MCUs help make meter reading autom PDF | HTML Sep. 23, 2016

Related design resources

Software development

WMBUS Wireless M-bus protocol software

Reference designs

TIDA-00646 Matched Precision Temperature Sensing Reference Design for Heat Cost Allocators TIDM-FRAM-WATERMETER Low-Cost Water Meter Implementation with FRAM Microcontroller Reference Design

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