ESP-Now Beacon fail

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I have been trying to build something that will allow my robot car to navigate autonomously to a beacon indoors.

The first attempt at this using Bluetooth didn’t work:

https://blog.ciaopslabs.com/2026/08/02/bluetooth-beacon-fail/

mainly because Bluetooth doesn’t have enough range.

The second attempt using ESP-Now (radio) has also not really worked, this time mainly due to the signal reflections indoors.

Initially, I started off by just swapping out the Bluetooth beacon code for the ESP-Now code but that didn’t seem to actually work. I then simplified it down to just a beacon and a responder. In effect, I replicated a sonar system where the responder would beep faster the closer it got to the beacon.

After plenty of testing I discovered that the reflections due to the indoors environment made it next to impossible to get reliable directions using this process. I have however uploaded the bacon code here:

https://github.com/directorcia/Azure/blob/master/Iot/LLM/beacon.ino

and the responder code here:

https://github.com/directorcia/Azure/blob/master/Iot/LLM/llm-sonar.ino

the recommended solution is to use UWB, which would mean at least 2 senors like this:

https://core-electronics.com.au/challenger-rp2040-uwb-dwm3000.html

which aren’t cheap if I am just testing.

Another option is to move the project to using robot vision, which I was going to get to and have done before. However, I’m going to have a think about whether this is the direction I want to go or perhaps it is time to try something new?

Controlling a robot car with AI

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After having AI show my fortune, the next project was having AI navigate my robot car.

To keep things simple I constrained movement to a 5 x 5 grid ( X = 0 – 4 and Y = 0 – 4) and the car could only move N, S, E or W one cell at a time. To get the algorithm right and test this with Ai before actually applying it to the car I simulated the result on the OLED screen I had previously configured.

With that all working I upgraded the code to run with the robot car and you’ll find it here:

https://github.com/directorcia/Azure/blob/master/Iot/LLM/llm-cellmove.ino

The main issue I found was more mechanical with the robot car wheels dragging and not being very precise, so the car woudl easily wander off in different directions. This has more to do with teh quality of the motors and wheels as well as the friction encountered when the wheels start moving. However, aside from that the test worked successfully and the car cycled up the grid and then back down.

Next, I wanted the AI to actually assist with the navigation of the car. I went through plenty of iterations with this. The most important change is that I moved from using a local AI to using Gemini via API calls. The main reason for this was simply speed. As the prompts became larger the local AI model struggled to return the results to the car in enough time to implement effective navigation. I had also wanted to integrate large cloud based LLM so here was the opportunity, so I hooked up Gemini.

The robot car also has an ultrasonic senor connected to a motor at the front so I could sweep it left and right as well for better object detection. However, initially I kept it simple and all on teh car by just using the ultrasonic sensor to detect hazards and try to makeover around them. The code for that is here:

https://github.com/directorcia/Azure/blob/master/Iot/LLM/llm-sweep.ino

I then upgraded the code to integrate the LLM into the navigation process by making decisions on which direction to turn. That code is here:

https://github.com/directorcia/Azure/blob/master/Iot/LLM/llm-sweep.ino

One issues I ran into, that wasted a lot of my time and was totally my own fault, was when I started having issues with the wheel moving the car forward. I blamed the code but in fact, again it was a hardware issue, being the battery charge had become too low to actually drive the wheels acceptably. It is interesting at how quickly that car now actually drains power when fully running.

With the power issues resolved I upgraded the code a number of times to allow the LLM a much higher level of navigation control. You’ll find the final result here:

https://github.com/directorcia/Azure/blob/master/Iot/LLM/llm-assist-nav.ino

The end result of all these experiments is that I have learned that in the full configuration the car now burns a lot of power as it moves, turns the sensor, communicates over wifi and more. all the changes I made to the code would make the car slightly less likely to crash into objects on the floor but a lot more though needs to go into ‘crash free’ navigation. The obvious improvement is to add more sensors to provide the LLM with more information to make better decisions. I also found that the wheel on the car are not precise enough and don’t really provide the best grip. This means they tend to be slow to engage and lag cause the car to veer.

I think all of these can be solved iteratively over time and I am confident that I can get to a situation that allows the robot car to move pretty much crash free around the floor just like a robot vacuum can already. However, the time required is probably not something that I’m willing to invest in just now to get a little incrementally better. I’m happy that my ‘proof of concept’ when it comes to navigation with LLMs works. I think it is time to move onto the next project.

Having the device show my fortune

After getting the ESP32 talking to the local LLM the next stage was to do something more than just flashing an LED. I decided that I’d use the LLM to produce a ‘fortune’ for me and then display that on an OLED screen I’d connect to the ESP32.

The OLED screen in question was this White I2C OLED display (SSD1306).

White I2C OLED display (SSD1306)

To use this OLED you need the Adafruit_SSD1306 library.

Here is the prompt being sent to the local LLM:

You are a mystical fortune teller. Give one short fortune. Maximum 12 words.  No introduction. No quotes.

The result from the LLM is then displayed on the OLED screen which is connected to the ESP32-C3-DevKitM-1 via GPIO6 and GPIO7 acting as SDA and SCL communication ports. I also left the external LED on GPIO4, from the last project, as well to aid troubleshooting.

The code is here:

https://github.com/directorcia/Azure/blob/master/Iot/LLM/llm-fortune.ino

and the results look like:

Screenshot 2026-07-10 084030

Video URL = ESP32 displaying results from local LLM

Getting device talking to LLM

With the LLM now up and working on a separate device on my LAN, the next step is to test it remotely to ensure that it works. For this I used the following simple PowerShell on a remote machine



which you will find here:

https://github.com/directorcia/Azure/blob/master/Iot/LLM/echo-ping.ps1

Next, I ran the following PowerShell script:

https://github.com/directorcia/Azure/blob/master/Iot/LLM/echo-test.ps1

which simply runs a standard prompt of;

“Reply with exactly: Hello from Ollama”

and then ensure that I get that reply back from the remote LLM server. This means I have communications to the actual server as well as the LLM.

With all the remote communications confirmed, the next step was to get a device talking to the LLM. For this I had a ESP32-C3-DevKitM-1 hanging around.



The main benefit of this device is that it has inbuilt Wifi. I connected up a LED and resistor to GPIO4 like so:





I then used this code in the device:

https://github.com/directorcia/Azure/blob/master/Iot/LLM/llm-flash.ino

to prompt the LLM for a number of flashes from 1 – 4, which the device would then complete that on the LED. I could also monitor the progress using the terminal, which would look like:

Connecting to Wi-Fi…..
Wi-Fi connected. IP: 192.168.1.42
Requested flash count: 3
Sending request to Ollama (attempt 1)…
HTTP status: 200
Ollama reply: {“flash”:3}

Initially I found that the LLM was returning the same number of flashes, so I needed to adjust the prompting to get some variation. The good news is that I got it all working and the resultant code is above.

So now I have successfully gotten a device talking to a local LLM. I’ll be expanding on this in upcoming articles but very happy that have this basic configuration all working now.