GPredict, rotctld to control rotator via Esp01 serial wifi

Hi All,

Is above possible, without extra serial port emulators and such, on widows 10? or maybe on Puppy linux?

I believe it may be possible, This topic seems to suggest so.

Unfortunately I do not understand Hamlib rotctld protocols well enough. I have tried!
I have been tearing the little hair I have out over the last few days and cannot figure this out.
Any help is appreciated, but please be kind to me and don’t leave obscure hints. :grinning:

Thanks in advance for any help.
Steve VK4SMC

Hi Steve,

Unfortunately I do not understand the setup you are trying to build, in particular the meaning of “serial wifi”.

Serial connection is used by hamlib to control the hardware and gpredict is not involved in that process. The only requirement for gpredict is to have a hamlib rotctld server running and accessible through a network connection, wifi or wired - it doesn’t matter.

Hi csete,
Thanks for replying so quickly. Re reading my post I did make it a bit vague, sorry for that.

The rotator that I have built is based on the Sarcnet mini rotator 1b.
This uses an Arduino controller to send and receive serial commands from rotctld.
The serial via usb cable works great, but I decided that a wireless serial control connection would be better.

I achieved this using an Esp-01s wifi adapter with esp-link firmware.
In the rotator the Arduino Pro micro still handles the serial tx & rx but now via the esp-01, which connects to my home wifi network.
On the same network my Windows 10 laptop then uses programs called com2tcp then com2com for virtual serial ports to handle the serial tx rx to rotctld. :woozy_face:
This also works, but I would like to simplify the setup.
Hope that makes sense.

The answer is probably very simple, but it eludes me.

Again Thanks
Steve VK4SMC

Okay, no I understand better :slight_smile:

A way to simplify it could be to add a small linux board that can talk to the arduino via usbserial and has wifi. You can then run rotctld on this board and gpredict could connect to it through wifi.


1 Like

Hi Alex,
Thanks again for your time.
Buying another board is not in the budget for a long time, but I may do that at a later stage.
I was trying to use the equipment I have.
Thought it would be a simple matter, Silly me.
If I do discover a simple way to do this I will post here for others.
Thanks again again.
Steve VK4SMC

The ESP board should be more than capable of running some code to emulate the rotctld protocol and present it via a TCP socket.

The protocol is very simple, I’m not sure how many of the commands gpredict uses, but at the very least you’d need to listen and respond to the ‘p’ (read position) and ‘P’ (set position) commands.

It definitely would work, I have built such capabilities in the Satran MK2 rotator ( now under development which runs on ESP8266. Takes only around 30 lines of code to start a TCP-server (called “socket”) on port 4533 and then listen/respond to rotctl commands like “P 360.0 90.0\n” so you can directly control it over wifi from Gpredict without any extra hardware. Its like a light-weight rotctld (“rotctl daemon”).

Hi Steve
Did you ever get this working?

Hi Mark,
The original setup I mention above in my second post does work fine.
My aim was to somehow simplify the path the commands and responses took/take.
The Esp01 just replaced the serial cable more or less.
I was not successful finding a simple fix with the parts I had at the time. Sorry.
What I ended up doing was buying an Esp12e and L293D Wifi Motor Drive Shield Module, which was not expensive.
Rewrote some of the code, put it on Esp12e instead of Arduino Pro micro, that seems to do what I want.
Hope this all makes sense and answers your question.

Hi Steve
Thanks for the reply.
Is it possible to get a copy of the code for the esp01 and Arduino?
Thanks in advanced

Hi Mark,
The code I used for the Arduino on this project was from The Sarcnet Mini Satellite-Antenna Rotator Mk1b scroll down the page to see link to latest firmware.
Be aware this is Not the Satnogs firmware.
Can’t really help much with code for the esp01, If I remember correctly I used the built in AT commands and a serial wifi adapter I found somewhere.
This Link may help with the AT commands. Also search for “Esp01 wifi serial”.
The code used at the time is lost Sorry.
Hope this helps a little.

Thanks for the info Steve.
I was able to get the Sarcnet MK2 working with an ESP01 on my Mega 2560 board.
I loaded ESP-Link on the ESP01 and telnet through it with Gpredict.
Works fine so far