Step 3 create a gauge app is about 80% complete. I have the Tempest gauge app running on the Gauge Data Transmitter (GDT) and pulling weather data from my Tempest. It is beaming the current temperature to a non existent WallGauge (building the physical gauge is the next step).
Little background on the WallGauge architecture if you’re interested. The WallGauge GDT is a kit you add to a Raspberry Pi Zero W that creates a platform for running Gauge Apps. Gauge Apps are responsible for acquiring gauge data and sending it to an analog gauge. Here is a very rough version of my Gauge App for the Tempest Weather Gauge on the WallGauge GitHub site. It is not complete, lacking documentation and only sends temperature data at the current time. Normally I wouldn’t share incomplete code but this post is about the process.
A GDT is managed with my IOS app called the GDT Administrator. The GDT Administrator is used to add / delete and manage gauge apps. Each gauge app has a logging screen to troubleshoot and monitor a Gauge App’s process. Here is a screen shot from my iPad of my Tempest gauge app pulling gauge data from the WeatherFlow API and sending it to a WallGauge.
Any chance of sharing the circuit for the gauges? and what kind of stepper motor you use?
I live in the UK and due to import duties and taxes it’s unlikely I’d ever be able to afford to but one but I’d love to have a go at making my own personal version of the gauge
If you’re thinking about starting from scratch there are a lot of good do it yourself projects for stepper control (here is one from Adafruit). I started this project back in 2017 with the goal of making it a commercial product that can be tailored based on the data to be displayed. If you are interested in more technical detail take a look at my post on the Parallax forum. In that forum I talked about the circuit design and assembly code I wrote to make it all work.
Finally got some time in the shop to put the finishing touches on the case. 13.25" diameter segmented turning of Padauk and hard Maple sanded from 80 to 3000 grit. Finished with my own home made friction polish.
I love the work on this and the functionality, but 12 batteries seems really excessive. Any chance of getting a common set of batteries? 3 AAs should still give you a healthy life between changes and be significantly less battery waste, or batteries to recharge with rechargeables.
@jkf I hear you. The short answer is yes you could run all the gauges off of one set of batteries but I don’t recommend it. I know it looks like a lot of batteries but AAA batteries are pretty cheep and they should last 12 to 18 months so it is not like you will be changing them a lot. Each WallGauge is a standalone system and I have to adhere to certain design guidelines so they meet FCC certification requirements. A WallGauge is a generic gauging platform intended to be used in various systems. If we did a central battery bank for a large gauge like this it would require us to certify each unique gauge configuration. We could do that it would just add to the cost of the overall system.
I’m pretty proud of the firmware that runs on a WallGauge and manages the power consumption. There was almost a year of testing and coding to get it fine-tuned. The motor we are using is an automotive stepper motor designed for an automotive dashboard. It is not designed to be energy efficient. We had to do a lot of cool stepping tricks to reduce the power required to move the stepper’s needle and have it “stick” in position when the power was removed. Traditionally steppers use power to even hold still. We had to overcome that with programing to get the year plus battery life. In fact our numbers are telling us that we will get over 2 years of battery life on 3 AAA batteries but I want to be cautious on what I tell people.
This is extremely cool. I definitely would want one. One question I have is why you used IR to feed the data. Where does that device sit? It appears there is a square hole below each dial that I am guessing is for the IR signal. Would it have been possible to have the device mounted behind the clock and hard wire it to the dials?
You got it. The Infrared receiver sits inside the little square in the gauge-face just below the center of each needle. I originally planned on covering it with a plastic (IR transparent) cap. But the little receiver is the exact size as the square hole and fills it nicely so it looks like a finished product.
The Infrared transmitter is called the Gauge Data Transmitter (GDT). One GDT can transmit data to several unique gauges (in the same room). There are several reasons I didn’t combine it in the actual gauge and hardwire it. One of my main goals was to make the gauges efficient and battery powered so they can easily hang on the wall like a battery powered clock. I also want to keep the cost down of the actual gauges and create a modular system where you can add gauges as you need based on the data to display. Another huge driving factor for using infrared over RF is certification cost. It is much more expensive and complex to certify a device that use Radio Frequencies.
The GDT is pretty small and can sit on a shelf or table. It should have clear line of site to the wall gauges in the room. But I have found that if it is within 25 feet and facing up it works as long as something is not laying on top of the IR LEDs.
I like your concept, ingenuity and craftsmanship!
and I am curious…
At 55 deg outside temp or 50% chance of precipitation could the needle counter weight block the infrared sensor?
And if full sun shines onto the clock face does it still work?
cheers Ian
There is about a 1/10" gap between the needle and the infrared receiver. The infrared light just needs a sliver of a gap to get in and work. So no it has not been a problem. If you place the GDT (IR transmitter) in a room with a normal height ceiling (say 10 to 12 feet high) it can sit flat pointing up and the IR light just bounces around and fills the room. The gauges can be just about anywhere in the room within 15 to 20 feet or so. On the other hand, if the ceiling is higher or the gauge is further away than 20’ you may need to point the GDT at the WallGauge. Sunshine has not been an issue with shining into the same room as a WallGauge. However, if the sunshine was directly on the IR receiver and the GDT was far enough away it may cause interference.
More information on the infrared transmitter (GDT) if your interested:
If I had to put my finger on the one thing that makes this work so well it would be our “IR Gauge Communication Protocol (IGC Protocol)” It allows us to put an addressed gauge command and value with error checking all in one 32bit packet (bit not byte). That is super efficient and allows us to drive the infrared LEDs in burst mode (very, very high power for just a few milliseconds). The GDT-PCB (pictured below) was first developed in 2017 after I came up with the IGC Protocol. The circuit has stayed the same but the software has been fine-tuned to maximize output over the years.
