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#### Assignment
This week, we were assigned with working with a partner or a group of 3 to program one or more microcontroller(s) to obtain and respond to information from the internet or radio, with at least one input and one output device.
Unfortunately, this was the week that I had COVID-19, and I was unable to partner up with anybody for this assignment. Thus, I attempted this assignment for the remote control part of my <a href="https://nchoi22.github.io/ps70/15_finalproject/index.html">final project</a> (which later was removed from the final project).
The goal was to have two ESP32S2 microcontrollers communicate with one another via radio, such that button inputs from one ESP could trigger motor movements on a NEMA17 stepper motor on the other ESP.
I first tried to do this using the LoRa RFM95W radio modules. These modules are a popular choice for long-range radio communication. I spent some time soldering wires to these modules, as shown below, and trying to connect the modules to the ESP32S2. However, I was not able to get the two microcontrollers talking, likely because I was not using the SPI communication protocol properly.
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<img src="/ps70/lora.png" class="img-responsive" style="width:100%" alt="Image"></a>
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At this point, I switched over to the ESP_NOW protocol, which allows two ESP microcontrollers to communicate with one another on a 2.4GHz frequency without any external radio modules. This was great, as this simplified things a lot and I didn't need super long range communication anyway. After some testing, I was able to get the two ESP's talking to each other and communicating. However, I was not immediately able to get the button functionality to work. I stopped working on this as I moved on to other portions of my final project, and when I returned to this functionality, the ESP32S2's were not able to communicate with one another for some reason. I still have not resolved this issue, but my efforts in achieving communication are below in the code.
The first snippet of code is for the "sender" ESP, which has two buttons for each direction the motor could move:
<pre><code>
#include <esp_now.h>
#include <WiFi.h>
#define BUTTON_LEFT 7 //GPIO pin connected to button
#define BUTTON_RIGHT 8
// REPLACE WITH THE MAC Address of your receiver
//uint8_t broadcastAddress[] = {0x70, 0x04, 0x1D, 0xFB, 0x35, 0x9C};
uint8_t broadcastAddress[] = {0x60, 0x55, 0xF9, 0xDF, 0xEA, 0x2A};
// 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 msg;
} struct_message;
// Create a struct_message called ButtonState to hold button message
struct_message ButtonState;
struct_message incomingReadings;
esp_now_peer_info_t peerInfo;
int lastStateLeft = LOW;
int currentStateLeft;
int lastStateRight = LOW;
int currentStateRight;
// 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);
}
void setup() {
// Init Serial Monitor
Serial.begin(115200);
pinMode(7,INPUT_PULLUP);
// Set device as a Wi-Fi Station
WiFi.mode(WIFI_STA);
// Init ESP-NOW
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
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() {
// send message if left button is pressed
currentStateLeft = digitalRead(BUTTON_LEFT);
if (lastStateLeft == LOW && currentStateLeft == HIGH) {
// Send message via ESP-NOW
ButtonState.msg = 5.0;
esp_err_t result = esp_now_send(broadcastAddress, (uint8_t *) &ButtonState, sizeof(ButtonState));
if (result == ESP_OK) {
Serial.println("Sent with success");
}
else {
Serial.println("Error sending the data");
}
}
lastStateLeft = currentStateLeft;
// send message if right button is pressed
currentStateRight = digitalRead(BUTTON_RIGHT);
if (lastStateRight == LOW && currentStateRight == HIGH) {
// Send message via ESP-NOW
ButtonState.msg = -5.0;
esp_err_t result = esp_now_send(broadcastAddress, (uint8_t *) &ButtonState, sizeof(ButtonState));
if (result == ESP_OK) {
Serial.println("Sent with success");
}
else {
Serial.println("Error sending the data");
}
}
lastStateRight = currentStateRight;
}
</code></pre>
The next snippet of code is for the "receiver", which has the stepper motor.
<pre><code>
#include <esp_now.h>
#include <WiFi.h>
#include <AccelStepper.h>
// Define an accelstepper object
AccelStepper stepper(1,9,10);
int incoming_value;
// REPLACE WITH THE MAC Address of your receiver
//uint8_t broadcastAddress[] = {0x60, 0x55, 0xF9, 0xDF, 0xEA, 0x2A};
uint8_t broadcastAddress[] = {0x70, 0x04, 0x1D, 0xFB, 0x35, 0x9C};
// 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 msg;
} struct_message;
// Create a struct_message called ButtonState to hold button message
struct_message ButtonState;
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);
incoming_value = incomingReadings.msg;
}
void setup() {
// Init Serial Monitor
Serial.begin(115200);
// ultrasonic
pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
pinMode(echoPin, INPUT); // Sets the echoPin as an Input
stepper.setMaxSpeed(3000.0);
stepper.setAcceleration(1000.0);
stepper.setSpeed(600);
stepper.setCurrentPosition(0);
// Set device as a Wi-Fi Station
WiFi.mode(WIFI_STA);
// Init ESP-NOW
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
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);
// initialize the incoming value to be 0
incoming_value = 0;
}
void loop() {
if (incoming_value == -5) {
stepper.moveTo(-10);
stepper.runToPosition();
incoming_value = 0;
}
else if (incoming_value == 5) {
stepper.moveTo(10);
stepper.runToPosition();
incoming_value = 0;
}
}
</code></pre>
Below is an image showing the circuit of the receiver:
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<img src="/ps70/messy_circuit.png" class="img-responsive" style="width:100%" alt="Image"></a>
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