PS70: Intro to Digital Fabrication

### Week 9: Radio, WiFi, and Bluetooth This week's project was program microcontrollers to have them talk to each other/the internet. Nina, Ana, and I teamed up to work on a cat button: a cat with a button that, when you press it, it sends a random cat fact to another microcontroller via bluetooth. The receiving microcontroller will then display the cat fact on an LCD display. The project had a bunch of components, which we split among our group members: <ul> <li>Modeling and printing the cat (Ana)</li> <li>Figuring out Bluetooth to send signals between microcontrollers (Nina and Ana)</li> <li>Making the button circuit (me)</li> <li>Writing the button press code (me)</li> <li>Wiring up the LCD screen and writing the code (me)</li> <li>Writing the code to get a random cat fact from the Cat Facts API (me)</li> <li>Putting it all together! (everyone)</li> </ul> Ana found a model of a cat she liked online, then modified it to make sure it was hollow: our idea was to have the cat holding the button in its paws, then we could run the wires down through the hollow cat. She then 3D printed it. I started working on wiring up the LCD screen (the Adafruit 1.14" 240x135 Color TFT Breakout LCD Display). This [tutorial and example code](https://learn.adafruit.com/adafruit-1-14-240x135-color-tft-breakout/arduino-wiring-test) from Adafruit was very helpful. Initially, the screen wasn't working when I used the example code, and it turned out my soldering job wasn't great. Ibrahim helped me fix it, but we did notice that the soldering iron was being a bit finicky (we're not sure why). Once I had the screen working with my Arduino, I wanted to shift it to the ESP-32. I figured out which pins on my ESP-32 were the SCK (SPI clock) and MOSI pins by using [this](https://forum.fritzing.org/t/esp32s-hiletgo-dev-boad-with-pinout-template/5357) pinout reference. After switching those around, the code still wouldn't work and I got stuck... I'm still stuck after consulting Nathan for a bit and will continue to work on this. I moved on and wrote the code to display the string the API will return. You can find it in the code snippet at the end! This was fairly straightforward, as Adafruit has a good information [source](https://learn.adafruit.com/adafruit-gfx-graphics-library) on the graphics library. Next came wiring the button circuit and writing that code, which was very straightforward. I hooked up the button to ground through a 10k pulldown resistor and connected the other end to a pin of the ESP-32 and power. Then, I wrote some quick code for the microcontroller to take an action (send the Bluetooth signal) once the button was pressed, and stop sending the signal once the button was released. Once Nina and Ana finish the Bluetooth code, I'll add that into the button press code. After that, I needed to investigate the cat facts API and figure out how to get a random cat fact. Navigating through the API documentation led me to [this](https://alexwohlbruck.github.io/cat-facts/docs/endpoints/facts.html) website, which told me the request I needed to get a random fact. I then used Nathan's [example](https://nathanmelenbrink.github.io/ps70/09_networking/index.html) of using the National Weather Service's API and adapted it to send a request to the cat facts endpoint. However, this didn't work, perhaps because the API requires some kind of login. I did some searching and we switched to this [random facts](https://uselessfacts.jsph.pl/) API instead of cat facts. Finally, I used the ArduinoJSON part of Nathan's tutorial to pull out the part of the returned payload that's just the fact string. Unfortunately, mid-project, Ana got a bad concussion and can no longer work on the project, so Nina and I worked together to finish as much as we could. We pivoted away from Bluetooth, and instead will have our ESP-32s talk to each other via ESP-NOW, and Nina worked on that code based on this [tutorial](https://randomnerdtutorials.com/esp-now-two-way-communication-esp32/). Nina and I managed to write all our code, but ran into a ton of issues, from my ESP not wanting to upload to hers completely not functioning. We did decide how we'll put everything together: the cat will hold the button. When the button's pressed, Nina's ESP will get a fact from the API, then send that fact to my ESP. My ESP will then display the fact on the screen, along with a message to press the button again for a new fact. We're now trying to fix all of the following issues. Once those are fixed, we'll paste our code at the end. <ul> <li>Figuring out how to make the LCD screen work for ESP-32</li> <li>De-bugging the code that makes our ESP-32s talk to each other</li> <li>Putting the button press circuit into the cat</li> </ul> After continuing to work on the project for a while, we managed to de-bug the ESP-NOW code by restarting with the tutorial and working through it again until the code worked. I also fixed the issues with the LCD screen: it turns out that I just accidentally messed up some pin numbers, and once I rearranged them, it worked totally fine. We were left with one final issue: while our ESP-32s were sending and receiving messages, they were being received as total gibberish (a bunch of backwards question marks and random characters). We checked our baud rates which were not the issue, then worked with Nathan to figure it out. We've tried changing the message from a structured message to just a string, which converted the total gibberish to just backward question marks: progress! We then tried changing the delay from 3 seconds to 10. We did some research and found that strings are a stubborn type of data and won't send if they're over 10 characters. We pivoted and used the National Weather Service API instead, to send the current temperature. However, this didn't work either. We spoke to Nathan and tried using the exact tutorial code for ESP-NOW on the PS70 website, but that also failed. Some more research later and We got the example code from the site to work by adding the line memset(&peerInfo, 0, sizeof(peerInfo)); before the line memcpy(peerInfo.peer_addr, broadcastAddress, 6); With the sample code working, we turned again to our project. Sadly, we never managed to get it to actually send the weather, it only sent a 0 from Nina's ESP to mine. We couldn't figure out what happened, especially because our ESP's were displaying successful sending of the data. Apparently, my ESP wasn't receiving it, but this didn't make any sense to us given that we didn't end up making a ton of changes to the tutorial code, and that worked. Nina's ESP also totally failed at some point and we had to replace it. We weren't able to totally finish the project given the repeated failures, unfortunately. But, you can see my part of our code below: <pre><code class="language-arduino"> <pre> <pre> #include <Adafruit_GFX.h>    // Core graphics library #include <Adafruit_ST7735.h> // Hardware-specific library for ST7735 #include <Adafruit_ST7789.h> // Hardware-specific library for ST7789 #include <Fonts/FreeMonoBoldOblique12pt7b.h> // Font #include <SPI.h> #include <WiFi.h> #include <Wire.h> #include <ArduinoJson.h> #include <HTTPClient.h> #include <esp_now.h> #include <Adafruit_SSD1306.h> #define TFT_CS        17 #define TFT_RST       16 #define TFT_DC        4 // For 1.14", 1.3", 1.54", 1.69", and 2.0" TFT with ST7789: Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST); //Code to set up receiving the string from Nina's ESP uint8_t broadcastAddress[] = {0xC8, 0xF0, 0x9E, 0x47, 0xDF, 0x68}; // Define variables to store incoming readings float incomingTemp; // Variable to store if sending data was successful String success; //Structure example to send data //Must match the receiver structure typedef struct struct_message {  float temp; } struct_message; struct_message incomingReadings; esp_now_peer_info_t peerInfo; // Callback when data is sent void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) {  Serial.print("\r\nLast Packet Send Status:\t");  Serial.println(status == ESP_NOW_SEND_SUCCESS ? "Delivery Success" : "Delivery Fail");  if (status == 0) {    success = "Delivery Success :)";  }  else {    success = "Delivery Fail :(";  } } // Callback when data is received void OnDataRecv(const uint8_t * mac, const uint8_t *incomingData, int len) {  memcpy(&incomingReadings, incomingData, sizeof(incomingReadings));  Serial.print("Bytes received: ");  Serial.println(len);  incomingTemp = incomingReadings.temp; } void setup() {  // LED Screen stuff  Serial.begin(115200);  Serial.print(F("Hello! ST77xx TFT Test"));  // Use this initializer if using a 1.14" 240x135 TFT: //  tft.init(135, 240);           // Init ST7789 240x135  // SPI speed defaults to SPI_DEFAULT_FREQ defined in the library, you can override it here  // Note that speed allowable depends on chip and quality of wiring, if you go too fast, you  // may end up with a black screen some times, or all the time.  //tft.setSPISpeed(40000000); //  Serial.println(F("Initialized")); //  uint16_t time = millis(); //  tft.fillScreen(ST77XX_BLACK); //  time = millis() - time;  // WiFi stuff  WiFi.mode(WIFI_STA);  if (esp_now_init() != ESP_OK) {    Serial.println("Error initializing ESP-NOW");    return;  }  // Once ESPNow is successfully Init, we will register for Send CB to  // get the status of Trasnmitted packet  esp_now_register_send_cb(OnDataSent);  // Register peer  memset(&peerInfo, 0, sizeof(peerInfo));  memcpy(peerInfo.peer_addr, broadcastAddress, 6);  peerInfo.channel = 0;  peerInfo.encrypt = false;  // Add peer  if (esp_now_add_peer(&peerInfo) != ESP_OK) {    Serial.println("Failed to add peer");    return;  }  // Register for a callback function that will be called when data is received  esp_now_register_recv_cb(OnDataRecv); } void loop() {  Serial.println(incomingTemp); //Print fact from Nina to serial monitor  delay(1000); /* tft.fillScreen(ST77XX_BLACK);  tft.setCursor(0, 75);  tft.setTextWrap(true);  tft.setRotation(1);  tft.setTextColor(ST77XX_BLUE);  tft.setFont(&FreeMonoBoldOblique12pt7b);  tft.setTextSize(1);  tft.println(incomingFact);*/ } /*  //Format and print fact to LCD display  void setRotation(uint8_t 3);  tft.fillScreen(ST77XX_BLACK);  tft.setCursor(0, 75);  tft.setTextWrap(true);  tft.setTextColor(ST77XX_BLUE);  tft.setFont(&FreeMonoBoldOblique12pt7b);  tft.setTextSize(2);  tft.println(incomingFact); */ /*  const int buttonPin = 18;  pinMode(buttonPin, INPUT);  buttonState = digitalRead(buttonPin);  if (buttonState == HIGH) {    send signal to the other ESP32  } else {    stop sending signal to other ESP32  } */ </pre> </pre> </code></pre>