67 replies to this topic

[mlord]

The HomeBrew WiFi+BT+GPS project here features bluetooth (BT) connectivity to the AUX bus of the mount, as does the HomeBrew All-In-One project.  This is potentially a great way to connect to and control the mount -- no software timeouts or power-saving nastiness to result in dropped connections.  I have long since sought such a connection method!

 

Unfortunately, this is of limited use at present, because CPWI is the only Celestron app that will use such a connection.  SkyPortal only knows about TCP network connections, which it inaccurately calls "WiFi".  SkySafari will do bluetooth, but ONLY with reduced functionality from a hand-controller connection, not from a full featured AUX port.

 

The solution, is to have the receiving device, a smartphone or tablet, convert that bluetooth connection into a fake TCP connection, which is something that CPWI, SkyPortal, and SkySafari all understand ("WiFi").

 

At first, this is pretty simple: 

1. Connect the HomeBrew accessory and power on the mount.

2. Pair the Android device with the HomeBrew-xxxxxx bluetooth.

3. Purchase (cheap) and install the Android BT/USB/TCP Bridge Pro app, and configure it to connect to the HomeBrew SPP/Bluetooth as "Device A".  Then configure "Device B" as a TCP Server on port 2000.  Done.

 

 

At this point, everything needed for an ongoing connection is there.  Except the Celestron apps still need to be told to connect to that TCP Server on the Android device.  The way this normally happens, is they listen for a UDP protocol "broadcast" message, which identifies the network address (MAC) of the device running the TCP Server.  Without that message, they don't know what device on the LAN to connect to.

 

So the remaining 10%, requiring 90% of the effort here, is to generate and send that broadcast message.  And this must be done from the same Android device that is running the Celestron and bridge apps.

 

The message itself is an ASCII string, sent as the payload of a UDP broadcast addressed to 255.255.255.255 port 55555.  The contents should be exactly this:

 

{"mac":"xx:xx:xx:xx:xx:xx","version":"HomeBrew-AMW007-9.0.0.0, 2021-05-13T12:00:00Z, ESP32-0.1"}

 

Except replace the xx:xx:xx:xx:xx:xx part with the MAC address of the Android device.  This can be manually obtained by going into Android Settings-->System-->Status and looking for the "Wi-Fi MAC address" within that maze of menus. Carefully hand copy it for future reference.

 

It can also be obtained more automatically by a script (read on..), but doing so requires superuser ("root") access, which most people have not set up on their device.  So the manual method is probably the only show in town.

 

Once you have the MAC, it's a matter of getting a simple shell script running on the Android device to do the broadcasts every couple of seconds.  Eg, something like this:

 

#!/bin/sh
MAC='xx:xx:xx:xx:xx:xx'
advert="{\"mac\":\"$MAC\",\"version\":\"HomeBrew-AMW007-9.0.0.0, 2021-05-13T12:00:00Z, ESP32-0.1\"}"
while sleep 2 ; do
  echo -n "$advert" | socat -u - UDP4-DATAGRAM:255.255.255.255:55555,reuseport,broadcast
done

 

This script uses the socat ("socket cat") command to send the broadcast messages.  It does NOT require "root" to run and work.  But the tricky bit is figuring out (1) where to get a socat command binary from, and (2) how to get the script to run.

 

I did manage it on my own set-up (https://www.cloudyni...5#entry11101542), and now am working on something simpler for others to try.

 

More later..

Edited by mlord, 15 May 2021 - 01:16 PM.

[mlord]

Some background on the Bluetooth interface:

 

Because I do all of this for fun, these various HomeBrew projects are using the simple Arduino IDE (Integrated Development Environment).  This provides a very simplistic and easy to use single-thread layer on top of whatever hardware/RTOS lies underneath.

 

The ESP32 chip has a custom RTOS built-in, with multiple CPUs and lots of operating system threads controlling various bits of hardware, including WiFi and Bluetooth.  But programming it "natively" is much more complex than through the simplified Arduino interfaces.

 

All of that said, the Bluetooth AUX bus interface could be made a lot easier to connect with, if only it used the Personal Area Network (PAN) features of the Bluetooth spec.  Doing it this way, would result in full TCP/IP over Bluetooth, and as a result nothing special needed on the smartphone/tablet side of things: SkyPortal and SkySafari would just see it as a TCP ("WiFi") device, even though the actual packets are flying over a Bluetooth interface.

 

One would just pair the smart device to the HomeBrew as a networking device, and the rest is automatic.  Probably even for iPhone/iPad users, as well as for the mainstream Android folks.  No bridge app needed.

 

The difficulty is.. much, much more complex programming required inside the HomeBrew, and it would probably have to move away from the Arduino IDE and use the more native ESP32 programming interfaces, which themselves are also much more complex.

 

There is a third-party Bluetooth implementation called BTstack -- https://github.com/b...ck/tree/develop -- which has been ported to native ESP32 already, and it supports writing PAN (TCP over Bluetooth) applications.  So this would be the way to go, should one want to pursue PAN for the HomeBrew stuff.

 

I am searching around to see if anyone has already gotten BTstack working for the Arduino layer on the ESP32, which would save enough effort that I might consider adopting it.  EDIT: Note that BTstack has already been ported to the Arduino IDE, for use with external serial-bluetooth modules, but not yet in combination with the built-in ESP32 bluetooth and Arduino.

 

Meanwhile, back to the current, more clumsy connection method! 

Edited by mlord, 15 May 2021 - 12:53 PM.

[jasonjeremiah]

I'm going to give this a try over the weekend as I do have that app on my phone already.  I've used it to bridge connections with other devices at work. 

 

Though, wifi connection with the HB has been working great lately.  I've had several nights of successful alignments and tracking using SkyPortal over wifi with the HB adapter.  Had lots of hiccups the first few times out with SkyPortal and SkySafari, but they've been spot on the past week or so as far as getting aligned and tracking.  Next step is to implement PHD2 and guide cam into routine so I can start guiding.  

Edited by jasonjeremiah, 15 May 2021 - 12:45 PM.

[mlord]

I have just now gone through the motions from scratch, this time setting this up on my Android-10 tablet.  Here are the exact steps I used to make it work:

 

Enable the Developer menus.  Exactly how varies by model/version.  See here:  https://www.greenbot...-or-tablet.html

 

From within the new Settings-->System-->Developer Options menu, enable USB Debugging.

 

Install the adb (Android DeBug) command-line tool on your PC (various ways, depending upon type of PC and version of operating system.  Easiest on Linux).

 

On the Android device:

Determine MAC address from Settings-->System-->About:  WLAN MAC address

(or from somewhere similar inside the Settings-->System menus).

 

Also, pair the Android's Bluetooth with the HomeBrew-xxxxxx device.

On the PC, create the bc (broadcast) script (cut and paste from below) and insert the MAC address:

 

#!/bin/sh
MAC='xx:xx:xx:xx:xx:xx'
advert="{\"mac\":\"$MAC\",\"version\":\"HomeBrew-AMW007-9.0.0.0, 2021-05-13T12:00:00Z, ESP32-0.1\"}"
while sleep 2 ; do
  echo -n "$advert" | /data/data/com.termux/files/usr/bin/socat -u - UDP4-DATAGRAM:255.255.255.255:55555,reuseport,broadcast
done

 

Connect the Android device to the PC over USB, and copy the bc script to the Android device:

 

   adb push bc /sdcard/downloads/

 

Alternatively, use any other method that works for you to get the bc file onto the Android device (removable sdcard, file-server app, USB stick, etc..).

 

Now, on the Android device:

 

Install the Android BT/USB/TCP Bridge Pro app from Google Play (purchase required).

 

Install F-Droid app from https://f-droid.org/

This is like a completely open-source supplement/alternative to the Google Play Store.

 

Use F-Droid to install the main Termux app.

Termux is a full-on Linux command-line environment for your Android device.

 

From Termux, do these commands:

## Install some necessary packages:
pkg upgrade
pkg install socat
 

## Grant Termux permission to access /sdcard/downloads and other stuff:
termux-setup-storage

 

## Move the bc script from /sdcard/downloads by doing this:
cd
mv storage/downloads/bc .
chmod 0755 bc

 

## Fix corruption introduced by using MS-DOS/MS-Windows to edit/transfer the file:

dos2unix bc 

 

## Run the script (it loops forever, use Control^C to stop it later):
./bc

 

Now run the BT/USB/TCP Bridge Pro app as described in post #1.

 

Finally, run SkyPortal or SkySafari, configured to use "Celestron WiFi" in "Access Point" mode.  Sometimes it takes a couple of tries for it to connect (I will fix this eventually).  Sometimes the BT/USB/TCP Bridge Pro app needs to disconnect/reconnect between attempts.

 

Once the SkyWhatever app does connect, things should be reasonably rock solid from then onward.

 

Yes, I'm exploring options to make this a LOT simpler.  But for now..

Edited by mlord, 16 May 2021 - 12:06 PM.

[mlord]

There are extensions for Termux, available through F-Droid, to make running the script easier after the initial one-time setup above.  Eg. the Termux:Widget package enables one to have an icon on the Home screen which will launch the bc (broadcast) script when tapped.

[Chote]

There are extensions for Termux, available through F-Droid, to make running the script easier after the initial one-time setup above.  Eg. the Termux:Widget package enables one to have an icon on the Home screen which will launch the bc (broadcast) script when tapped.

Hi Mark,

 

Thanks for the detailed instruction. I'm quite familiar with the command line. I've followed your instruction until completed; and also installed termux:widget. However I'm not sure how to create a shortcut for bc. Could you elaborate more?

 

When I run the bc directly from the command prompt there was an error; then run it with 'sh bc' it produced another error.

 

Thanks

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Edited by Chote, 16 May 2021 - 02:57 AM.

[mlord]

Ahhh.. Microsoft MS-DOS (aka. "Windows") rears its ugly head again.

In this case, it has added control^M characters to every line of the original file.

 

You'll have to get rid of those.

I have updated the original instructions now with an extra step to do that (dos2unix).

 

I haven't used the shortcut thing myself either.

 

Cheers

Edited by mlord, 16 May 2021 - 06:04 AM.

[mlord]

I just tried the shortcut thing, and.. well, not perfect but it does work.

 

After installing the Termux:Widget package from F-Droid, I simply followed the instructions it showed, which say that it works with scripts that appear inside the $HOME/.scripts directory.

 

So.. within Termux, I did this:

 

cd

ln -sf ../bc .shortcuts/   ## fixed; had this line wrong originally

 

Then back to the Android Home screen:  press and hold on a blank part of the Home screen, and select Widgets from the pop-up menu.  Scroll down until you find Termux Shortcut 1x1, and tap on that.  It will present a list of available scripts from the .shortcuts/ directory.  In this case, it's a VERY short list consisting of just the bc script.  Tap on bc and it will put an icon onto the Home screen for it.

 

Now.. the problem then seems to be getting the script to stop running after it has been launched.  So to avoid that, change the script before you run it:

 

#!/bin/sh
MAC='xx:xx:xx:xx:xx:xx'
advert="{\"mac\":\"$MAC\",\"version\":\"HomeBrew-AMW007-9.0.0.0, 2021-05-13T12:00:00Z, ESP32-0.1\"}"
for i in a b c d e f g h i j k l m n ; do
  echo -n "$advert" | /data/data/com.termux/files/usr/bin/socat -u - UDP4-DATAGRAM:255.255.255.255:55555,reuseport,broadcast

  sleep 2
done

exit 0

 

Probably best to do that on a PC and then follow the original steps to transfer it again to the Android device.  Or, if you grok vim (the enhanced vi editor clone), then install and use it directly from within Termux:   pkg install vim

Edited by mlord, 17 May 2021 - 04:53 AM.

[mlord]

It has occurred to me that, as Termux presents a complete Linux development environment on my tablet.. I'm now pretty much in my native environment. 

 

Which means I suppose I could write a Linux program to take care of the Bluetooth bridging to TCP, as well as the UDP broadcast packets, and then package that up as a much simpler single-item install to do everything discussed here thus far, probably without the need for Termux or the paid bridge app.

 

I may look into this, if we don't get a solution from the bridge app's author -- he did get in touch and is looking at it though.  Promising.

[coollick]

Interesting, now I know why my first attempt with the BT/USB/TCP Bridge Pro app didn't work for me. 

I may be able to code a small android app (apk) to do the UDP broadcasts, I saw a similar example and I think I can do it.

Edited by coollick, 16 May 2021 - 11:03 PM.

[Chote]

Got this error when press the bc shortcut on home screen; however I can run bc directly in Termux without problem.

Sent from my M2007J3SG using Tapatalk

[mlord]

Got this error when press the bc shortcut on home screen ..  Too many symbolic links encountered

My mistake.  Corrected the original instructions now.  This works:

 

cd

ln -sf ../bc .shortcuts/   ## fixed; had this line wrong originally

Edited by mlord, 17 May 2021 - 04:53 AM.

[mlord]

Interesting, now I know why my first attempt with the BT/USB/TCP Bridge Pro app didn't work for me. 

I may be able to code a small android app (apk) to do the UDP broadcasts, I saw a similar example and I think I can do it.

Good!  Because I just heard back from the original app guy, and he's passing on this one.

 

If you can figure out the code to do broadcasts, then the Android Studio also includes a sample app for reading/writing to a Bluetooth connection..  The only other piece we will need is how to listen and accept connections on a TCP socket.

 

I know how to do all of this in C on Linux -- literally half an hour tops to implement the whole sheebang -- but I get lost quickly going through all of those extra API layers and objects on Android.  I wonder if I can find something convert a regular Linux app into a clickable Android widget, but without the end-user having to install/use an entire Termux distribution?

[mlord]

Ha!

The set-up just got a little bit easier..  It turns out that the "mac","xx:xx:xx:xx:xx:xx" portion isn't needed by SkyPortal or SkySafari6+.  Which makes sense, because that same info is already part of the broadcast packets at a lower layer.

 

So.. no need to determine the device's MAC address or hand-edit the script.

Instead, just this:   [EDIT: improved, smaller script]

 

#!/bin/sh
while [ "$i" != "30" ]; do
  echo -n '{"AMW007"}' | socat - UDP4-DATAGRAM:255.255.255.255:55555,broadcast
  sleep 1
  i=$((i+1))
done

Edited by mlord, 17 May 2021 - 10:32 AM.

[mlord]

I just heard back from the original app guy, and he's passing on this one.

Or.. maybe not. 

I've got him exploring the idea more now.

[mlord]

I have updated the script above yet again.. smaller and simplified.

It now runs for 30-seconds after launching, then terminates again.

 

So you have 30-seconds to connect with SkySafari or SkyPortal after starting the script.

Edited by mlord, 17 May 2021 - 10:14 AM.

[mlord]

While we all wait with baited breath to see if the Bridge app guy comes through for us, I decided to have a crack at an easier-to-build HomeBrew Bluetooth accessory.

 

This one uses a very simple Arduino module for the prototype, along with a HC-05 BlueTooth module.  Plus a diode and some pull-ups to interface with the telescope mount's AUX bus.

 

After a bit of fiddling, it works!  With StarSense, even! 

 

I assembled the prototype using a 3.3V Arduino Pro Micro that was on hand, but plan to re-do it shortly using a 5V Arduino Pro Mini board, because things just work better at 5V.

 

 

The code is very simple for this, and construction effort is on par with the HomeBrew GPS project: again quite easy to build one of these.  Certainly much easier than a HomeBrew WiFi or All-In-One project would be.

 

A slight complication is the need to reprogram the default baud rate of the HC-05 Bluetooth module, from the too-slow default of 9600 to a more generous 38400.  And change the Bluetooth SSID from "HC-05" to "HomeBrewBT" while one is at it.   But this can be done automatically with a one-time jumper/switch setting prior to first use.

 

Plans and code to be made available on request, as usual.

Edited by mlord, 18 May 2021 - 05:44 AM.

[coollick]

I've got the UDP broadcast working in an android app.

It does the same as your script, just hit a button and it sends 30 packets (1 per second)

Confirmed with Wireshark, I left my scope/homebrew device at the cottage.

 

I will generate an apk file probably tomorrow and post it.

 

Coded in C# with Visual Studio, Xamarin Forms. (I can do java but it gives me headaches having to create intents for everything...   )

So if anyone has a developer subscription with Apple (I don't, not interested), I will gladly share the code.

 

Next is to try and implement the BT<->TCP bridge. I have never done that but the idea seems simple enough.

Edited by coollick, 17 May 2021 - 10:22 PM.

[Chote]

While we all wait with baited breath to see if the Bridge app guy comes through for us, I decided to have a crack at an easier-to-build HomeBrew Bluetooth module

 

This one uses a very simple Arduino module for the prototype, along with a HC-05 BlueTooth module.  Plus a diode and some pull-ups to interface with the telescope mount's AUX bus.

 

After a bit of fiddling, it works!  With StarSense, even! 

 

I assembled the prototype using a 3.3V Arduino Pro Micro that was on hand, but plan to re-do it shortly using a 5V Arduino Pro Mini board, because things just work better at 5V.

 

homebrewbt.jpg

 

The code is very simple for this, and construction effort is on par with the HomeBrew GPS project: again quite easy to build one of these.  Certainly much easier than a HomeBrew WiFi or All-In-One project would be.

 

A slight complication is the need to reprogram the default baud rate of the HC-05 Bluetooth module, from the too-slow default of 9600 to a more generous 38400.  And change the Bluetooth SSID from "HC-05" to "HomeBrewBT" while one is at it.   But this can be done automatically with a one-time jumper/switch setting prior to first use.

 

Plans and code to be made available on request, as usual.

It would be nice to incorporate GPS function in this project, unless you see the Arduino board can't handle both functions.

[mlord]

It would be nice to incorporate GPS function in this project, unless you see the Arduino board can't handle both functions.

The low end Arduino was having trouble enough as-is, so I removed the GPS code.

 

But later on the cause of trouble here, and likely the same as for the 3.3V ethernet module, was finally uncovered:  The hardware UART receive buffer size chosen by Arduino is too small.  Once I bumped it up to 128 (from 32 or 64 bytes), everything suddenly worked reliably.

 

So GPS could probably be reinstated, though I'm not sure of the use for it.  The Bluetooth/AUX is intended for SkySafari/SkyPortal, neither of which will use GPS from the mount.

 

Cheers
 

Edited by mlord, 18 May 2021 - 06:45 AM.

[mlord]

I just heard back from the original app guy, and he's passing on this one.

..

Or.. maybe not. 

I've got him exploring the idea more now.

More than just "exploring", it seems..

He has just released an update to the app with this feature incorporated and working very well.   Talk about a sudden embarrassment of riches! 

 

Anyone who wants to try it, this is the Android BT/USB/TCP Bridge Pro app, available on Google Play for a mere $0.99 at the moment:  https://play.google....&hl=en_US&gl=US.

 

EDIT:  The new features needed here are only available in a pre-release BETA version of the app.  So not generally available yet to others here.  But soon..

 

To use it here, first purchase and install the app, and then visit this link to sign up for the BETA program: https://play.google....toothbridge.pro.  After doing that, wait a few minutes, and then revisit Google Play and install the new updated BETA version that will appear.

 

In the BETA version, just set up "Device A" to be "classic bluetooth device" (the HomeBrew must be powered on and paired with Android already).  For "Device B" then select "TCP Server", and check both boxes for "Allow new.." and "Broadcast UDP..".  Set the UDP Packet data to {"AMW007"} (including the brace brackets and double quotes) and the Remote UDP Port to 55555

 

After that, fire up SkyPortal or SkySafari in "Access Point" Celestron Wifi mode, and connect!

 

To automate the Bridge app settings, go to the app menu (top right corner) and tap on "Autostart setting", then follow the prompts.  Very cool.

 

Cheers
 

Edited by mlord, 18 May 2021 - 07:58 AM.

[mlord]

More than just "exploring", it seems..

He has just released an update to the app with this feature incorporated and working very well.   Talk about a sudden embarrassment of riches! 

 

Anyone who wants to try it, this is the Android BT/USB/TCP Bridge Pro app, available on Google Play for a mere $0.99 at the moment:  https://play.google....&hl=en_US&gl=US.

...

And for anyone miserly like myself, who wants to know how good the app is before paying for it, the author has sent me a limited number of "3-Month Free Trial" vouchers, which should be valid within a few hours of now.  Message me if you need one.  I will post here again when they run out.

 

Cheers

[coollick]

Nice, at that price, its not even worth the effort but I may keep my project for a rainy day. (I am thinking just a simple one purpose app, choose your BT device, set-it and forget kinda thing)

 

I purchased the app, the developer was kind enough to give us a solution quickly. 

 

I don't have access to the Beta version, looks like we need an invitation :

" App not available for this account

Your account isn't currently eligible for this app's testing program.
If you've been invited to become a tester, make sure you're signed in to the account that was invited to the testing program. If you've been invited to a Google Group as part of the program, make sure you've joined the Group. "

 

But I will wait a few days, maybe that will change now that I have (re)purchased the app or the new release version will come out soon.

[mlord]

Thanks for that note.  I'll get in touch with him again about expected release -- didn't realize it required an invitation!

[Chote]

I contacted the developer asking for being a beta tester. He responded quickly and said the latest beta version 3.8 still have some bug:

 

"Note: in v3.8 there is a bug when UDP broadcast address might not be correctly determined. This will be fixed shortly."