Mechanical engineering scholar Tommy Liao wanted a solution to precisely measure very small issues on a price range — so discovered a trick to get serial readings from low-cost micrometers with out having to attach them to a PC’s USB port by the corporate’s comparatively costly information seize device.
“Utilizing some evaluation + hacking of the communication protocol used within the Clockwise Instruments dial indicator,” Liao explains of the reverse engineering mission, “we create the chance to digitally learn the micrometer with lower than $50 per device. Sign evaluation utilizing an AD2 reveals that the clock and sign traces, which might be accessed by a micro-usb interface, might be extracted from the D+ and D- traces respectively.”
If you happen to’ve bought a Clockwise Instruments dial in your toolbox, this sensible mission can get it speaking. (📷: Tommy Liao)
Clockwise Instruments’ dial indicators embrace what the corporate says is an RS232 serial connection for studying measurements electronically, with out having to look on the digital show. Whereas this presents on a micro-USB connection, it isn’t really USB: as a substitute, it wants a customized converter, the Clockwise Instruments DTCR-01 RS232 Information Cable, and requires a guide button press to switch every studying.
Sad with this guide method, particularly given the adapter prices greater than the device to which it is being related, Liao determined to reverse engineer the connection and construct another utilizing an Arduino Nano suitable microcontroller board. “The clock is proven to differ from dial gauge to dial gauge,” Liao explains, “however the indicators all have the identical format: as soon as each ~40ms, we now have a ‘burst’ of a nibble. Six nibbles are communicated on this time-frame, with a time division of ~1.58ms between every of those nibbles.”
Liao has revealed a wiring diagram plus full supply code, although warns that the sign clock varies between dial fashions. (📷: Tommy Liao)
By decoding these bursts with the Arduino, it is potential to interchange the official cable at a a lot decrease value — or to make use of them as enter into another system, with Liao suggesting such tailored instruments may discover use in 3D printing and pc numeric management (CNC) programs. The readings will also be taken routinely, taking away the guide button-push of Clockwise Instruments’ personal answer.
The complete mission write-up, together with wiring diagram and supply code, is out there on Hackaday.io.