mbed Application Board Application board for ESP32 Node32s

As described in Notes the application board has been designed to enable the maximum number of potential experiments and projects, with the minimum footprint.

Although that there are 2x20 way headers for the mbed for jumper wiring pins off-board, it's a fairly well encapsulated platform.

With the addOn board the ESP32 board NodeMCU32s can be used.

Feature list¶

1. 128x32 Graphics LCD
2. 5 way joystick
3. 2 x Potentiometers
4. 3.5mm Audio jack (Analog Out)
5. Speaker, PWM connected
6. 3 Axis +/1 1.5g Accelerometer
7. 3.5mm Audio jack (Analog In)
8. 2 x Servo motor headers
9. RGB LED, PWM connected
10. USB-mini-B Connector
11. Temperature sensor
12. Socket for for Xbee (Zigbee) or RN-XV (Wifi)
13. RJ45 Ethernet Connector
14. USB-A Connector
15. 1.3mm DC Jack input

128x32 LCD¶

An Arduino ESP32 example program to print text to the LCD

#include <U8g2lib.h>
U8G2_ST7565_NHD_C12832_F_4W_HW_SPI u8g2(U8G2_R2, 5, 14, 13); // rotation = 180° = U8G2_R2 // VSPImosi(GPIO23), VSPIclk(GPIO18)

char buff[20];

void setup(void) {
  u8g2.begin();
}

void loop(void) {
  sprintf(buff, "Hello World");
  u8g2.setFont(u8g2_font_ncenB08_tr);
  u8g2.drawStr(0,30,buff);
  u8g2.sendBuffer();
}

Joystick¶

An example program for the mbed application board that uses the joystick button. LED1,2,3,4 light in sequence with up, down, left, right.

int ledPins[] = { 19, 17, 16,  4 }; // an array of pin numbers to which LEDs are attached
int joyPins[] = { 33, 26, 32, 27 }; // an array of pin numbers to which the JoyStick is attached
int pinCount = 4;                   // the number of pins (i.e. the length of the array)
int reading, prev, led;

void setup() {
  for (int thisPin = 0; thisPin < pinCount; thisPin++) {
    pinMode(ledPins[thisPin], OUTPUT);
    pinMode(joyPins[thisPin], INPUT_PULLDOWN);
    digitalWrite(ledPins[thisPin], HIGH);
  }
}

void loop() {
  for (int thisPin = 0; thisPin < pinCount; thisPin++) {
    reading = digitalRead(joyPins[thisPin]);
    if(reading == HIGH) {
      prev = led;
      led = thisPin;
    }
    digitalWrite(ledPins[led], LOW);
    digitalWrite(ledPins[prev], HIGH);
  }
}

Potentiometers¶

Sends ADC values between 0 and 4095 to serial port, so open Tools->Serial Monitor with 115200 baud:

uint8_t ADC6 = 34; 
uint8_t ADC7 = 35; 
uint16_t adcPoti2, adcPoti1; 

void setup() {   
  Serial.begin(115200);       
  Serial.println("\n DAC\mbed\tPoti1->ADC5(P33)\tPoti2->ADC4(P32)"); 
} 

void loop() {    
  adcPoti2 = analogRead(ADC6);     
  adcPoti1 = analogRead(ADC7);     
  Serial.printf("ADC: Poti1=%04d\tPoti2=%4d\n", adcPoti1, adcPoti2); 
  delay(500); 
}

See also ADC-Poti|ADC-Poti

Analog Out¶

ToDo: 3.5mm Audio jack not connected.

Speaker¶

A frequency sweeps up and down.

const int speaker = 12;     // 12 corresponds to GPIO26
 
const int freq = 5000;      // setting PWM properties
const int spkrChannel = 0;
const int resolution = 8;
 
void setup(){
  ledcSetup(spkrChannel, freq, resolution);
  ledcAttachPin(speaker, spkrChannel);
}
 
void loop(){
  for(int dutyCycle = 0; dutyCycle <= 255; dutyCycle++){   
    ledcWrite(spkrChannel, dutyCycle);
    delay(15);
  }
  for(int dutyCycle = 255; dutyCycle >= 0; dutyCycle--){
    ledcWrite(spkrChannel, dutyCycle);   
    delay(15);
  }
}

See i.e. https://os.mbed.com/users/4180_1/notebook/using-a-speaker-for-audio-output/

3 Axis +/1 1.5g Accelerometer¶

See this [[https://os.mbed.com/users/fpucher/code/ESP32/wiki/I2C-Axis-Accelerometer|site]] for a description.

#include <Wire.h>
#include "MMA7660.h"
 
MMA7660 accelemeter;
 
void setup() {
  accelemeter.init();  
  Serial.begin(9600);
}
 
void loop() {
  int8_t x, y, z;
  float ax,ay,az;
  enum {BufSize=50};  
  char buf [BufSize];
  float myFloat = -1.012;
 
  Serial.println("******************************************");
  accelemeter.getXYZ(&x,&y,&z);
  snprintf (buf, BufSize, "x=%d y=%d z=%d", x, y, z);  // snprintf is safer than sprintf
  Serial.println(buf);
  accelemeter.getAcceleration(&ax,&ay,&az);
  snprintf (buf, BufSize, "ax: %.2fg  ay: %.2fg  az: %.2fg", ax, ay, az);
  Serial.println(buf);
  delay(500);
}

Analog In¶

ToDo: 3.5mm Audio jack not connected.

Servo Motor¶

See mbed Servo

RGB LED¶

An example program that cycles the on board RGB LED through various colours.

#define mbedLED_R 0   // GPIO00
#define mbedLED_G 2   // GPIO02
#define mbedLED_B 15  // GPIO15

void setup(){
  pinMode(mbedLED_R, OUTPUT);
  pinMode(mbedLED_G, OUTPUT);
  pinMode(mbedLED_B, OUTPUT);
} 
 
void loop(){
  digitalWrite(mbedLED_R, !digitalRead(mbedLED_R));
  delay(1000);
  digitalWrite(mbedLED_G, !digitalRead(mbedLED_G));
  delay(1000);
  digitalWrite(mbedLED_B, !digitalRead(mbedLED_B));
  delay(1000);
}