THERMOsera - 4 channel thermocouple USB/UART interface

THERMOsera is an interface to connect thermocouple sensors via USB or UART to a host system. It senses K-type thermocouple elements on four channels and outputs the measurement result on the UART interface or on a virtual serial port (CDC) through USB.

Four channels with 300ms/channel sampling interval (4 channels -> 1,2s interval)
Plain text serial output over USB and UART with bluetooth option
Build-in temperature sensor for cold junction compensation
Bootloader for firmware updates
Open source firmware

Serial output

Format - Plain text CSV

After power up THERMOsera beginns to measure the four sensor channels and the cold junction temperature and prints it out over the serial interfaces (UART: 9600 Baud, USB: virtual serial port). The temperatures are sampled and printed out line-by-line as comma separated values (CSV) in degree Celsius:

 Channel-A, Channel-B, Channel-C, Channel-D, ColdJunction [CR]

Example:

    30.9,    10.6,    -5.7,    127.4,    22.4
    30.9,    10.6,    -5.6,    128.3,    22.4
    30.9,    10.6,    -5.4,    129.5,    22.4

Data lines start with a space character (" ") and ends with CR (13).

USB - Virtual serial port (CDC)

For Linux, MacOS and Windows >8 no additional driver is needed! THERMOsera is automatically detected as virtual serial port.

Driver for Windows <8:

THERMOsera_Win_Driver.zip

THERMOsera is mapped to serial port "/dev/ACMx" (Linux, MacOS) or "COMx" (Windows). You have to select this corresponding port in the software. On some Linux systems, "modemmanger" blocks the port for about 20s after plug-in (if this disturbs: disable or remove the modemmanager).

UART - 9600 Baud

THERMOsera features an UART interface (connector X6). The board can be powered through this connector (USB left open) or through the USB connector with an USB power adapter. The transmit line (TXD) is shifted down to 3,3V level (voltage divider R4/R5) to be compatible with 3,3V-5V systems.

Bluetooth - Optional HC-06 module

The UART pinout matches with HC-06 bluetooth modules. The HC-06 bluetooth module is an UART-to-Bluetooth board and can be connected to the UART socket while THERMOsera is powered via the USB connector with +5V. No additional firmware stetting is needed - just plug in the module and power the board. The serial output can be printed out e.g. on Andorid with the App BlueTerm.

Software

For further processing, the serial output can be written to a file.
Windows:

type com3: >> temp.csv

Linux or MacOS:

cat /dev/ttyACM0 > temp.csv

This file can be opened in spreadsheet software like Excel or LibreOffice Calc (use "US-English" as column format).

THERMOsera Libre Office Calc

Firmware

Source code and HEX file

The firmware of THERMOsera is available as precompiled HEX file and as C (XC8 compiler) source code.
The source code is hosted on Github: THERMOsera Source code.

Precompiled HEX file:

THERMOsera_firmware_v1.0.hex (2016-10-03) First public version

Firmware update via bootloader

Connect MCLR (X7) to ground and plug in THERMOsera. Now the bootloader starts. Use a bootloader application (

MPHidFlash) to load the new firmware into THERMOsera:

mphidflash -w THERMOsera_firmware_v1.0.hex

Hardware

Schematic - THERMOsera's circuit diagram

Partlist - Build your own THERMOsera!

Here you find a list of all parts needed to build your own THERMOsera board.

Partnumber	Value
C1	4,7u
C2, C3, C4, C5, C6	220n
IC1	PIC16F1455
IC2	MCP3424
IC3	MCP9800
R1, R6	470k
R2, R3	10k
R4	1k
R5	2k
X1, X2, X3, X4	2pol 5mm
X5	USB-B

Gallery

Please tell me about your Thermosera project!

		THERMOsera EB with Thermocouple connectors mounted on plastic plates. by Thomas Fischl (09/2017)
		Bert has worked intensively with the THERMOsera, achieved a very high accuracy (successfully tested: 0.1°C in the range 0-100°C) by using an adapted firmware and a specially developed Windows software. by Bert (09/2021)
		3D printed enclosure for THERMOsera. Two parts, mounted with four M3x12 screws (flat head). STL 3D files: THERMOsera_Case_02.zip by user community (11/2022)

Links

8-Channel Thermocouple Input USB Data Acquisition Device