In my previous post, I did a review of the 6000 counts ennoLogic eM860T true RMS multimeter. This meter is based on a signal chip design using the versatile DTM0660L DMM chip. Besides the ennoLogic eM860T, several other multimeters such as UNI-T 139C, Velleman DV4100, Tekpower TP40 etc. are also based on the same chip.
One key feature of this chip is that most of the configurable parameters as well as the calibration data are all stored in an external EEPROM. This means that we could potentially change certain settings and enable certain settings (e.g. enabling UART communication, backlight duration, auto power off duration, etc.) by just changing values in the configuration EEPROM without having to do any hardware modifications. We will take a look at how to make these configuration changes in this post.
Since sigrok (a cross-platform signal analysis software suite) already added support for the DTM0660 chip, we can use the sigrok-cli command line utility to talk to the meter via UART/RS232 once we have the functionality enabled .