TTGO Altimeter

[bdureau]

Hi All
The other day I was looking at making a simple altimeter with a display similar to the Joly Logic or Estes one so I looked around and bought a TTGO board.
TTGO seams to be very easy to integrate in a 3D printed case they are numbers odf example on Thingiverse
https://www.thingiverse.com/search?q=TTGO&page=1

Anyway I built a quick prototype with a barometer, accelerometer and eeprom. Within minutes I was able to run some simple code to display the current altitude and acceleration. Next I will make some nice menu and graphs to save the flights. I will also do a pcb that fits under the TTGO board. The battery can be charged up with a USB cable. I am currently testing the sleep mode of the ESP32 so that I can turn it off without adding a switch. Should be a fun project. I will make the code available OpenSource on my GitHub
https://github.com/bdureau

 

[cwbullet]

Pretty cool stuff.

 

[Spacedog49Krell]

This is my version of the Estes Altimeter. I built it for a high school science teacher to measure the altitude of the class water rockets.

 

[bdureau]

Nice. I have started mine in order to do rocket challenges in my Rocketry club. Plan is to do quite a few so that if we loose them it will not cost to much to replace.

 

[Lonnie Utah]

This is my version of the Estes Altimeter. I built it for a high school science teacher to measure the altitude of the class water rockets.

Nice! What voltage does it operate? 3.3vdc or 5vdc? I think you could make it even smaller!!

I've always had trouble getting those CR3032 button battery holders to fit inside a 25mm body tube. Below are the batteries I generally use. They are the smallest/cheapest lipo's I've been able to find. They're rated at 40mah. They'll fit vertically in a 19mm body tube, but the rest of my electronics package will not. If anyone interested I can post the Amazon link.

 

[Spacedog49Krell]

Nice! What voltage does it operate? 3.3vdc or 5vdc? I think you could make it even smaller!!

I've always had trouble getting those CR3032 button battery holders to fit inside a 25mm body tube. Below are the batteries I generally use. They are the smallest/cheapest lipo's I've been able to find. They're rated at 40mah. They'll fit vertically in a 19mm body tube, but the rest of my electronics package will not. If anyone interested I can post the Amazon link.

That project ran on 3-6vdc. The first version used two CR3032's for power. Later versions were powered with a 100mAh LiPo and easily fit in a 20mm body tube. The latest iteration, 18mmX70mm @30gm, is a 10 channel LPR flight computer recording data at 860Hz. A friend is working on a 13mm altimeter at 1.5 gm.

I would be interested in the Amazon link.

 

[kramer714]

Nice! What voltage does it operate? 3.3vdc or 5vdc? I think you could make it even smaller!!

I've always had trouble getting those CR3032 button battery holders to fit inside a 25mm body tube. Below are the batteries I generally use. They are the smallest/cheapest lipo's I've been able to find. They're rated at 40mah. They'll fit vertically in a 19mm body tube, but the rest of my electronics package will not. If anyone interested I can post the Amazon link.

BE really careful with these, some of the amazon batteries have the polarity reversed in the plug - by design.

 

[Lonnie Utah]

Thanks for the heads up. I always cut the plug off and re-soldered them anyway.

I can't count the number of multimeters I own lol. I used them for everything...

Amazon.com 40mah Lipo battery

 

[kenstarr]

Looks amazing! I'd love to get my hands on one.
Ken

 

[OzHybrid]

there is a TTGO module that incorporates a 900MHz Tranciever and a UBlox8?GPS. T-Beam. Can you get that to work?

LILYGO® TTGO T-Beam Devices​

All T-beam models (with the exception of the S3-Core) have an 18650 size battery holder on the rear of the device. This is designed to the original specification of the 18650 and only fits unprotected flat top 18650 cells. Button top and protected cells are typically longer than 65mm, often approaching 70mm.


Further information on the LILYGO® T-Beam devices can be found on LILYGO®'s GitHub page.

• v0.7
• v1.1
• M8N
• M8N & SX1262
• S3-Core
• Supreme

T-Beam with M8N and SX1276​

• MCU
  • ESP32 (WiFi & Bluetooth)
• LoRa Transceiver
  • Semtech SX1262 (improved performance)
• Frequency options
  • 433 MHz
  • 868 MHz
  • 915 MHz
  • 923 MHz
• Navigation Module
  • NEO-M8N - GNSS receiver (supports GPS, GLONASS, Galileo, BeiDou) (better GPS sensitivity)
• Connectors
  • Micro USB
  • Antenna: U.FL antenna connector

 

[bdureau]

For the moment I am trying to make it simple. The battery I have fits under the TTGO board and I have designed a PCB that clips under the ttgo
To give you an idea this is how big it will be

 

[OzHybrid]

For the moment I am trying to make it simple. The battery I have fits under the TTGO board and I have designed a PCB that clips under the ttgo
To give you an idea this is how big it will be
View attachment 632779

Are you making the boards available? PCBWay link? Or something similar...

 

[bdureau]

I will probably do what I normally do, sell some board for those interested to cover the cost of development and I will make the code opensource like the rest of my altimeters
https://github.com/bdureau

 

[OzHybrid]

Nice! What voltage does it operate? 3.3vdc or 5vdc? I think you could make it even smaller!!

I've always had trouble getting those CR3032 button battery holders to fit inside a 25mm body tube. Below are the batteries I generally use. They are the smallest/cheapest lipo's I've been able to find. They're rated at 40mah. They'll fit vertically in a 19mm body tube, but the rest of my electronics package will not. If anyone interested I can post the Amazon link.

CR3032 would be 30mm dia, 3.2mm thick so would be really difficult to get a 30mm battery in a 25mm tube.
For all of the CR series (coin round) the last 2 digits are the thickness in 0.1 mm increments 32=3.2mm etc
CR = lithium 3.7v ish SR= silver chemistry1.55v ish( watch batteries) long life.

 

[bdureau]

It is going to be 25mm wide and I have a 400mA/h batterie that is under the board. Battery can be charged up using a USB type C cable

 

[bdureau]

The 2 buttons allow to navigate, I am recording flights data in a EEPROM and I am now playing up with fancy graphics to display the results.

 

[Lonnie Utah]

It is going to be 25mm wide and I have a 400mA/h batterie that is under the board. Battery can be charged up using a USB type C cable

I'm assuming it charges through the on board USB-C connector? Connected the the 5v VCC output on the board? I'm also assuming the lipo has an on board charging voltage regulator?

Super compact, I like it.

The only thing left to do is 3d print a case for it...

 

[bdureau]

That is correct that is using the board charging circuit.
Yes I have seen lot's of design around that I could get inspired to make a nice case

And to turn it off I am using the ESP32 sleep mode. I will do a quick vidéo when I am done with it

 

[bdureau]

I am pretty much done with the main code functionnalites. Just did a quick video to give an idea on ahow it works.


Remaining to do an interface so that it is compatible with my Android front end so that the flight can be shared using Whatsapp, email etc ... like my other altimeters.

For those interrested the code is on my Github
https://github.com/bdureau/TTGOBearAltimeter

 

[Spacedog49Krell]

I am pretty much done with the main code functionnalites. Just did a quick video to give an idea on ahow it works.


Remaining to do an interface so that it is compatible with my Android front end so that the flight can be shared using Whatsapp, email etc ... like my other altimeters.

For those interrested the code is on my Github
https://github.com/bdureau/TTGOBearAltimeter

I'll check your code out. I have two TTGO's.

 

[bdureau]

I have just finished adding support so that it can connect to my Console Android application
Latest code of my console can be found here
https://github.com/bdureau/BearConsole2
I will do a new realease on the Android store

 

[bdureau]

Just some pictures of the screens

 

[-Slick-Ice]

Definitely an interesting project. The display is a great idea and I like how compact it is.

I've been looking for one of the T-Beam Supreme with the U-Blox M10S GPS but they have been out of stock for a while. I just ordered a few of the RAKwireless wisblock mini, accelerometers, and barometers. I assume the accelerometer will be maxed out every flight being only rated for 16G.

I'm still looking for something useful to do with these other than just tracking.

 

[bdureau]

I can replace the ADX345 by an ADXL375 if I need to do high speed flights!!! It is just a matter of changing the chip and the software.

 

[CrashLab]

Why use an EEPROM instead of a Flash chip?

 

[bdureau]

Very good question.
This is because I have re-used my old AltiMulti code which is compatible with other processor such as the ATMega328, STM32 and all the data logging is using the EEPROM. I guess one day I could re-write all that part. Let's face it it took me less than a week to do it working on it only evenings. ... I now have a fully fonctionnal altimeter that can also communicate with my phone and share flight data with others using email, whatsapp etc ...

 

[bdureau]

This is what the final product looks like

 

[cerving]

Why use an EEPROM instead of a Flash chip?

You can write one or two bytes to an EEPROM without having to write an entire page. It potentially saves data integrity... if you buffer until you have a full page to write, you put that data at risk. To do the same thing with flash you'd have to read and cache the page in memory, and re-write the entire page to change even one byte... not very efficient. Once you cache the page you can skip the page read as long as you're on the same page, but you still have to write the entire page to change one byte.

Flash is best at saving large amounts of data at a time... especially if you have to buffer the incoming data anyway (i.e. video).

 

[bdureau]

I am using an eeprom because of the code re-use. Anyway it has been a fun project that demonstrate how easy it is to port and adapt Arduino code to a different board. Overall less than a week of effort

 

[bdureau]

I did a 3D printed case

The altimeter can communicate with an Android device to display the flights