Archive for October, 2009

TEMPer Temperature Sensor Linux Driver

October 17, 2009

In addition to the Tenma driver, I just finished writing a driver for the TEMPer usb temperature sensor. I found that much of the information on the Internet regarding linux drivers for this device was wrong. Perhaps they refer to a different version of the part. The usb device I received uses a customized HID chip. You can find the linux driver here. Note that this driver is based on the libusb user space library and is not a kernel level driver. The driver can be compiled either as a standalone program or as a library to your own application. Permissioning is handled with a udev rule file.

Tenma 72-7730 in Linux

October 4, 2009

I bought a Tenma 72-7730 DMM for work so we could record data from our temperature chamber. The DMM is reasonably priced for a USB based instrument. Unfortunately it did not come with a driver or software for linux, only windows, so I was stuck reverse engineering the interface. The USB is based on a Hoitek UART to USB device that interfaces into the linux HID code instead of the serial tty driver. The Hoitek site is currently down (looks like they lost their domain name, maybe they were bought or something) but I found enough documentation on the internet to set the bit rate for the device so I could see what was coming on the HID interface. Long story short, here is the resultant gnu/linux software to fetch raw data, screen readings, and floating point values from the DMM. The software can be run stand-alone or as a library forĀ  your own application. Instructions are included.