Important Note:

The errata listed here applies only to revision 1 of the book. 

Revision 2 was published on 29 December 2024 and has all of these errors corrected.

Errata

Page 157

change

Stepperbi stepper1=Stepperbi();
void loop() {
  stepper1.step(1);
  delay(10);
}

to

Stepperbi stepper1=Stepperbi(16);
void loop() {
  stepper1.step(1);
  delay(10);
}
void setup(){};

 Page 254

Change

void setup() {
  Serial.begin(9600);
  Serial1.begin(9600, SERIAL_8N1, 2, 1);
  Serial1.setTimeout(30);
}
void loop() {
  char buffer[100];
  Serial1.write("Hello World\n");
  int len = Serial1.readBytes(buffer, 100);
  buffer[len] = NULL;
  Serial.printf("\nrecieved data: %s\n", buffer);
  while (true) {};
}

to

void setup() {
  Serial.begin(9600);
  Serial1.begin(9600, SERIAL_8N1, 2, 1);
  Serial1.setTimeout(30);
}
void loop() {
  char buffer[100];
  Serial1.write("Hello World\n");
  int len = Serial1.readBytes(buffer, 100);
  buffer[len] = NULL;
  Serial.printf("\nreceived data: %s\n", buffer);
  delay(1000);
}

i.e. change the final loop for delay and correct spelling 

Chapter 14

Use pins GPIO12 and GPIO13 for rx and tx rather than GPIO2 and GPIO3 thoughout - GPIO2 is a strapping pin
and sometimes changes the boot mode of the ESP32 on startup. Also connect GPIO12 to GPIO13 for loopback.

That is change:

Serial1.begin(9600, SERIAL_8N1, 2, 1);

to

Serial1.begin(9600, SERIAL_8N1, 12, 13);

Page 258,  259, 263,  274, 275, 281, 282, 284, 304, 307

Some ESP32 devices do not change baud rate from upload until loop is called. 

This is a bug but a simple fix is to set the baud rate a second time and wait.  

That is change

void setup() {
  Serial.begin(9600);

to 

void setup() {
  Serial.begin(9600);
  delay(2000);
  Serial.begin(9600);

 

 

Page 283

 Change  

void wifiConnect(char* ssid, char* password) {
  WiFi.onEvent(WiFiEvent);
  status = WiFi.begin("ssid", "password");
}

 to

void wifiConnect(char* ssid, char* password) {
  WiFi.onEvent(WiFiEvent);
  status = WiFi.begin(ssid, password);
}

 Remove quotes from ssid and password.

Page 347

Change

printf("%llX\n", count);

to

Serial.printf("%llX\n", count);

Page 351

Change

printf("%llX %d\n", data,uxQueueSpacesAvailable(q));

to

Serial.printf("%llX %d\n", data,uxQueueSpacesAvailable(q));