Projects / Measurements, sensors and data acquisition
Laboratory 16-channel temperature recorder based on precise TMP117 digital sensors and STM32: several I2C buses and simultaneous measurement of many points.
A laboratory needed to measure temperature in 16 points at the same time. Commercial multichannel solutions were expensive, while only one precise single-channel instrument was available for reference checks. The task was to assemble an affordable multichannel recorder with good repeatability.
A 16-channel temperature recorder was assembled on STM32 and TMP117 sensors. The sensors were placed on small boards and connected with cables up to about 15 m, which is a strong practical result for I2C. The system showed good channel consistency and was used in working experiments instead of the expensive calibrated single-channel instrument.
Project materials
Engineering context
TMP117 sensors have a limited number of I2C addresses, so several buses were needed for 16 channels.
The chosen development board did not have enough hardware I2C interfaces, so one of the buses had to be remapped in software.
The sensors were placed on long wires of about 10-15 m, which required careful connection work.
Accuracy was checked by comparison with a precise single-channel reference instrument and by measuring all sensors together in a stable environment.
Work done
Selection of precise TMP117 digital temperature sensors.
Small sensor-board design and assembly.
STM32 firmware and connection of 16 channels.
Organization of several I2C buses and software remapping of one bus.
Temperature data collection from all channels.
Comparison with a precise single-channel reference instrument.
Check of channel spread in a shared stable environment.
Details
The project started from a practical laboratory need: many temperature points had to be measured, but buying an expensive multichannel instrument was not desirable. The engineering approach was to use precise digital sensors, a simple development board and build a system for the specific experiment.
Each sensor had a limited number of available I2C addresses. To obtain 16 channels, several buses were used. When hardware I2C interfaces were not enough, one interface was reassigned to different physical pins.
According to the project owner, the system worked well: it was compared with an expensive precise single-channel instrument, and when all sensors were placed together in water they showed a small spread. As a result, real measurements were performed with this custom multichannel recorder.
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