Serial X.27 Stepper Motor Gauge

Name: Serial X.27 Stepper Motor Gauge
SKU: 6012
Price: 17.50 USD
Availability: InStock
Rating: 4.72 (8 reviews)

(8 Reviews)

analog gauge - with simple serial commands

Designed by snafu in Canada

2015-10-27T04:02:59.686Z-Drive From Pi.png

2015-10-27T04:02:59.686Z-Drive From USB Serial.png

2015-10-27T04:02:59.686Z-Hookup To USB Serial.png

2015-10-27T04:02:59.686Z-Hookup To Pi.png

2015-10-27T04:02:59.686Z-parts layout.png

2015-10-27T04:02:59.686Z-parts included.png

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analog gauge - with simple serial commands

This is a micro-project to produce a completely standalone serial driven gauge motor, for retrofitting into pretty much any analog display or meter that can be driven with just a single data line; wi…

Uses

Replace an old broken analog mechanism with a modern digital replacement
Create a steampunk style gauge using modern data feed
Custom automotive gauges

The board has its own on-board driver CPU, so there's no need to worry about multiple I/O pins, current drivers, flyback diodes, or step timing in your own source code; just hook up a single serial line and go. Also, because the input is opto-isolated you can swap polarity, and drive it from anything from 3.3v up to 15v (RS-232). There's even a spot on board for an on-board regulator in case you're using it on a 12 volt supply for your own custom automotive gauges.

It uses the very common X27.168 stepper motor to drive a pointer, the same stepper that is found (and widely available) in many car dashboards to drive the gauges you look at every day. I've found that if you don't have a good pointer you're going to re-use, go down to a local hobby store (or online) and find a nice clock hand that will suit your purpose; or even a gauge pointer off an automotive gauge. Even if the size doesn't fit exactly, a small dab of glue fixes that.

Specs:

315 degrees of rotation in 1/3 degree increments
Supply voltage from 5v to 12v
Serial data voltage all the way up to 25v (opto isolated from supply, and reverse polarity protected)
Run multiple gauges in parallel (requires software change on each gauge)

Kit contains:

Serial Gauge PCB (also available separately)
Diodes, Resistors, Capacitors
Pre-programmed ATTINY Microcontoller
Opto Isolator and voltage regulator (for use above 5v)
Headers for both power/data and re-programming using an Atmel ISP
M2 screws to mount everything

All of the source code (including optimized stepper motor libraries), along with photos, assembly instructions and hookup ideas, can be found on our Github page here: https://github.com/snafu-ca/serial-gauge

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Quantity	Price
1-4	$17.50
5+	$15.00

Review Breakdown

Average Ratings

Product: (5.00)

Documentation: (4.50)

Shipping: (4.50)

Communication: (4.88)

Philip | Dec. 12, 2023

A great unit

Soldering it up was fast, and the assembly instructions on Github were great.
I connected it to an ESP32 and was talking to it via Serial2 on pin TX2 in minutes.
The unit works exactly as hoped.

Sigmund | Aug. 20, 2021

Perfect!

I had this board up and running in less than 5 minutes. Very easy one-wire serial interface, and needle movement is precise and stable.

Tom | Nov. 9, 2020

Very neat little product

Had an issue with missing component, quickly dealt with by seller.

Actual product works great, great way to use x27 motors quickly and easily

Norbert | Nov. 7, 2020

Everything ok

Want to create a gps speedo for my bike. Cross the fingers....

Arrived in Germany after app. four weeks after purchasing ..

Greetings from germany,
Nobbi

John | Feb. 11, 2018

great board!

I ordered 5 of these. They only take a few min to assemble and all work exactly as described on the first attempt.

T | Sept. 5, 2017

Great board, super flexible

This is a well thought out board with lots of nice features, like the optoisolators. It is very flexible and provides nice smooth motion.
I had some problems zero'ing the gauge as it was not responding to the "!" command. The dev (boffin) responded to my questions which I find impressive seeing as I bought this almost 3 years ago.

I had to reflash the ATTiny to get the zero working and for me had to change the SwitecX25 library to get the zero working reliably. The motor would try to turn but seemingly not have enough power. It did move fine in normal positioning commands. This post https://github.com/clearwater/SwitecX25/issues/4 was the fix and suggested changing a delay constant used in the zero function.

#define RESET_STEP_MICROSEC 2000

I leave this here for any others with the same issue. May it save you many hours of googling about.

P | May 16, 2016

Nicely done!

From presentation to documentation it's all there and nicely commented. I was up and running in under an hour. The boards were easy to build and the Arduino examples worked the first try.

<Edit 1/1/17> I have to point out how amazing this product is. It allows you to hook up to 26 X27 gauges to a single pin on a uC/uP. All the stepping and the step speeds are handled by the ATTiny on the serial gauge board freeing up your uC to something else or go to sleep. The maker has added an 'init point' mode that makes storing and restoring gauge position a breeze, super handy if you're turning off the gauge between updating to save power.

David | Dec. 22, 2015

Unusual product with many uses

I bought a couple of these and they are really a fun item to play with.

I used one to "repair" an old steam pressure gauge which was mechanically beyond repair. I didn't need the full 315 degrees as there were mechanical stops which I chose not to remove. I used the original needle with some araldite and nobody will ever know it is electronic now.

Note: you may have to take smaller steps with heavy needles as the needle mass does affect the stepper performance (read the data sheet and look as the code for more information).

Something to watch out for - if you have a mechanical stop and you try to step beyond it, the display will no longer be correct as the stepper motor has no feedback. I thought that entering a position of 0 would execute a zeroing action but it doesn't. I am going to add a re-zero command so that in 24/7 use I can make sure the needle position is correct by issuing a re-zero from time to time. For now, power off and on and the dial will re-zero.

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