A1). UART communication

Before I start with this par of the assignment we need to understand about UART communication.

UART Communication stands for Universal asynchronous receiver-transmitter. It is a dedicated hardware device that performs asynchronous serial communication. It provides features for the configuration of data format and transmission speeds at different baud rates. A driver circuit handles electric signaling levels between two circuits. A Universal asynchronous receiver-transmitter (UART) Communication is usually an individual component or part of an integrated circuit. We can use it for communications over a computer or its peripheral devices such as a mouse, monitor or printer. In microcontroller chips, there are usually a number of dedicated UART hardware peripherals available.

Universal Asynchronous Receive Transmit (UART) or Serial communication is one of the most simple communication protocols between two devices. It transfers data between devices by connecting two wires between the devices, one is the transmission line while the other is the receiving line. The data transfers bit by bit digitally in form of bits from one device to another. The main advantage of this communication protocol is that its not necessary for both the devices to have the same operating frequency. For example, two microcontrollers operating at different clock frequencies can communicate with each other easily via serial communication. However, a predefined bit rate that is referred to as baud rate usually set in the flash memory of both microcontrollers for the instruction to be understood by both the devices.

Data from: UART communication

A2). UART communication

First I need to prepare the connection. This is what i'm going to need:

• Two ESP32 development boards
• Connecting Wires

A3). Connections between components:

In this section i'll show how the connections should be:

A3.1.) Xiao ESP32-S3 configuration.

• Define a xiao as master and the other one as slave.
• Connect TX2 pin of master ESP32 with RX2 pin of slave ESP32.
• Connect RX2 pin of master ESP32 with TX2 pin of slave ESP32.
• Both ESP32 boards have their grounds in common.
• The baud rate of both ESP32 master and slave boards should be the same.

A4.) Xiao ESP32-S3 connection.

In this part i'm goint to connect two xiao ESP32-S3. As I commented in the last section we got to make sure to connect everything properly. Let me show you how I did it:

• I set one of the Xiao as server (left one in the image) and the other one as a client (rigth one in the image.)
• I connect it the Tx of the server to the Rx of the client.
• Then I connect it the Tx of the client to the Rx of the server.
• And ground to ground (green cable).
• It's important to have in hand the pin diagram of yout microcontroller.

• FYI: before making any connection a test the pins to verify they were working, I use a multimeter.
• Then I upload a code for the "server" xiao and another code for the "client" xiao.
• In this part i got to be careful and make sure to upload different codes to each Xiao.
• Something that help me was using Tinkercad and simulate.
• In the right image below you can see the led is on.
• This took several days, I had several inconvenients.

• And after several hours of work I got it!!!
• And of course several p.i.c.n.i.c errors..........

A1). Turning on the Built_In sensor via wi-fi.

I will try to turn on and off a led via Wi-fi. The idea is to send a signal to the XIAO_ESP32S3 so it can change the state of the led.

A2). Scanning wi-fi networks

As my first part of this assignmets I have to make sure my ESP32-S3 detects wi-fi networks. I use an example from the IDE Arduino. I clic con:

• File
• Example
• Wifi
• Wifi scan

In the next images you can see the result of the scanning:

1. In the fisrt image you can see that the initial scanning wasn´t detecting any wi-fi networks. FYI: i'm at the university, I thought it was a security thing or something but I didn't have the antenna connected yet (P.I.C.N.I.C error).
2. In the second one, after connecting the antenna, it show the networks that were available.
3. And just to see how much time it took to detect another wi-fi network, I turn on my hotspot. You can see the name

A3). Now, i'm going to connect to the internet

Now that I know that my Xiao detects the wi-fi networks, i'm going to try to connect to one of them. In this part I try another code and:

• It compile correctly.
• I had to change the SSD and Password to my credential.
• I use SSD: WIFI PAD and the correct password.
• It didn't work, I assume theres a security thing going on.

Now I will try with another network and see if it works. Important, I have to change the credentials (SSD and password).

• In my second shot the code compile correctly.
• I change the SSD and Password to my credential.
• I use SSD: PAD and the correct password.
• I waited for a few minutes and it didn't work either.
• In both cases I make sure the credentials were right.

I decide to make a third shot. Hotspot from my cel phone but connected to the universities wifi. So let´s give it a shot.

• Third shot, the code compile correctly.
• I change the SSD and Password to my credential.
• I use SSD: WIFI PAD (hotspot) and the correct password.
• Had the same result as the first two tries.

This is my fourth try, now i'm using my internet and activating my hotspot. Hope this works!. So let´s give it a shot.

• Fourth shot, the code compile correctly.
• I change the SSD and Password to my credential.
• I use SSD: bazzinga! (my internet hotspot) and the correct password.
• And nothing happend