Week 13-14    Project ESP32

Introduction

For our final project we were given the opportunity to either fabricate the IoT Temperature Monitor that we designed in Homework 2 or the ESP32 module that was designed in Homework 3. I chose to fabricate the ESP32 module as I enjoyed learning and designing the module in Homework 3. In order to creat the module, we needed to design the module using EAGLE, have the PCB fabricated through PCBWay, solder all the necessary parts to the PCB board, and finally test the module.

Design

To design the PCB needed to create the ESP32 module we needed to use EAGLE. The first thing we needed to do was to find the right low-dropout (LDO) voltage regulator to use for our module. The Texas Instrument TLV7510 voltage regulator was selected as it best fit the specifications for our module. In EAGLE we needed to create the TLV7510 component as shown in Figure 1. Once we had all the required parts to design our module in EAGLE we created a schematic to connect the components as shown in Figure 2. After the schematic was completed, the BRD layout could be created where we could place the components on the PCB as desired and route the PCB, which is shown in Figure 3. Then when the board was routed we could finally pour the copper to finish the board and we would have a finished product that would be ready for fabrication as shown in Figure 4.

Figure 1. Created TLV751 Voltage Regulator


Figure 2. EAGLE schematic of module


Figure 3. Routed PCB with errors due to the vias


Figure 4. Finished PCB

Fabrication

Once we had the PCB created we created the gerber files that would be sent to PCBWay so they could fabricate the board. Before sending the gerber files, we needed to use an online PCB viewer like PCB Investigator to check to make sure the board was designed correctly as shown in Figure 5. Once we confirmed everything looked correct we sent Dr. Li our gerber files so he could order the PCB from PCBWay that way we can get a fabricated PCB like the one shown in Figure 6.

Solder

Once we had our boards it was time to solder all the parts onto it. We used a mixture of the hot air blower and the soldering iron to put the parts on the PCB board. After we got all the parts on the board as shown in Figure 7, it was time to test our board.

Testing

MASTER CODE:
#include "FS.h"
#include "SD.h"
#include "SPI.h"
#include<esp_now.h>
#include<WiFi.h>
#include<Wire.h>
const int MPU=0x68;//Device address
int16_t AccX, AccY, AccZ;
uint8_t broadcastAddress[] = {0x24, 0x62, 0xAB, 0xF9, 0x24, 0xC8}; // Receiver's mac address

typedef struct struct_message{
    int16_t AccX, AccY, AccZ;
} struct_message;

struct_message MPU6050Readings;

void setup(){
    Wire.begin(); //To redefine the I2C pins: Wire.begin(SDA,SCL) or Wire.begin(SDA, SCL, Bus_Speed).
    Wire.beginTransmission(MPU);
    Wire.write(0x6B);//Wake up the MPU chip
    Wire.write(0x00);
    Wire.endTransmission(true);
    Wire.beginTransmission(MPU);
    Wire.write(0x1C);//Talk to the ACCEL_CONFIG register (1C hex)
    Wire.write(0x08);//Set the register bits as 00001000 (+/- 4g full scale range)
    Wire.endTransmission(true);     
    Serial.begin(115200); // It's fine to use a higher speed other than 9600 but remember to change the rate in your serial monitor
    WiFi.mode(WIFI_STA);
    if (esp_now_init() != ESP_OK) {
      Serial.println("Error initializing ESP-NOW");
      return;
    }
    esp_now_peer_info_t peerInfo;
    memcpy(peerInfo.peer_addr, broadcastAddress, 6);
    peerInfo.channel = 0;
    peerInfo.encrypt = false;
    if (esp_now_add_peer(&peerInfo) != ESP_OK){
      Serial.println("Failed to add peer");
      return;
  }
}
void loop(){
    accRead();
    MPU6050Readings.AccX=AccX;
    MPU6050Readings.AccY=AccY;
    MPU6050Readings.AccZ=AccZ;
    esp_err_t result = esp_now_send(broadcastAddress, (uint8_t *) &MPU6050Readings, sizeof(MPU6050Readings)); //Send the data. &MPU6050Readings is just a 8-bit character pointer to store the data
}
void accRead(){ // read the MPU data to ESP32
    Wire.beginTransmission(MPU);
    Wire.write(0x3B);//Start with register 0x3B
    Wire.endTransmission(false);
    Wire.requestFrom(MPU,6,true);// Read 6 registers total
    AccX=Wire.read()<<8 | Wire.read();
    AccY=Wire.read()<<8 | Wire.read();
    AccZ=Wire.read()<<8 | Wire.read();
    Wire.endTransmission(true);
}

SLAVE CODE:

#include "FS.h"
#include "SD.h"
#include "SPI.h"
#include<esp_now.h>
#include<WiFi.h>
#include<Wire.h>
int16_t incomingAccX, incomingAccY, incomingAccZ;
const int MPU=0x68;//Device address

typedef struct struct_message{
  int16_t AccX, AccY, AccZ;
} struct_message;

struct_message incomingReadings;

void OnDataRecv(const uint8_t * mac, const uint8_t *incomingData, int len) {
  memcpy(&incomingReadings, incomingData, sizeof(incomingReadings));
  incomingAccX=incomingReadings.AccX;
  incomingAccY=incomingReadings.AccY;
  incomingAccZ=incomingReadings.AccZ;
}
void setup(){
    Serial.begin(115200);
    WiFi.mode(WIFI_STA);
    if (esp_now_init() != ESP_OK) {
      Serial.println("Error initializing ESP-NOW");
      return;
    }
    esp_now_register_recv_cb(OnDataRecv);
}
void loop(){
    Serial.print(incomingAccX);
    Serial.print(" ");
    Serial.print(incomingAccY);
    Serial.print(" ");
    Serial.println(incomingAccZ);
}

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