- Version
- System Diagram
- Differences to v1.5
- Development Boards
- Strapping Pins
- Input Only Pins
- Analog Pins
- JTAG
- LED Matrix
- Ambient Light Sensor
- Issues, Ideas And Bugs
- License
- Contribution
PCB board v2.0
- The clock crystal in v1.5 was removed, because it wasn't used.
- The I2S interface was added for digital microphones, like the INMP441.
- ESP32 Dev Kit C V4 will be used instead of ESP32 DEVKIT V1.
- It is also possible to use the Adafruit ESP32 Feather V2 instead of the ESP32 Dev Kit C V4.
| ESP32 DevKit V4 Pin | ESP32 DevKit V4 Pin Header | WROOM32 Pin | Notes | Usage |
|---|---|---|---|---|
| 3V3 | J1-1 | 3V3 | 3.3 V output | +3V3 |
| EN | J1-2 | EN | 10k Pull-Up; Button on ESP32 DevKit V4; Active High | RESET |
| VP | J1-3 | GPIO 36 (VP) | Input only! See ESP32 tech. reference manual, chapter 4.1 (no internal pull-up/down circuitry) | - |
| VN | J1-4 | GPIO 39 (VN) | Input only! See ESP32 tech. reference manual, chapter 4.1 (no internal pull-up/down circuitry) | - |
| 34 | J1-5 | GPIO 34 | Input only! See ESP32 tech. reference manual, chapter 4.1 (no internal pull-up/down circuitry) | LDR Analog In |
| 35 | J1-6 | GPIO 35 | Input only! See ESP32 tech. reference manual, chapter 4.1 (no internal pull-up/down circuitry) | - |
| 32 | J1-7 | GPIO 32 | Input only! See ESP32 tech. reference manual, chapter 4.1 (no internal pull-up/down circuitry) | - |
| 33 | J1-8 | GPIO 33 | I2S microphone serial data. | I2S_Data_IN |
| 25 | J1-9 | GPIO 25 | I2S microphone word select. | I2S_WS |
| 26 | J1-10 | GPIO 26 | I2S microphone serial clock. | I2S_CLK |
| 27 | J1-11 | GPIO 27 | Data Out to LED matrix | LV-DATA-OUT |
| 14 | J1-12 | GPIO 14 | Output PWM at power-up! | MTMS |
| 12 | J1-13 | GPIO 12 | Strapping pin; Fails if high at power-up, therefore not used. | MTDI |
| GND | J1-14 | GND | Ground | GND |
| 13 | J1-15 | GPIO 13 | - | MTCK |
| 2 | J1-16 | GPIO 9 (D2) | Pin shared with Flash Memory (Can´t be used as regular Pin) | - |
| 3 | J1-17 | GPIO 10 (D3) | Pin shared with Flash Memory (Can´t be used as regular Pin) | - |
| CMD | J1-18 | GPIO 11 (CMD) | - | - |
| 5V | J1-19 | 5V0 | external power supply | VCC-PROTECTED |
| GND | J2-1 | GND | Ground | GND |
| 23 | J2-2 | GPIO 23 | - | Test Pin |
| 22 | J2-3 | GPIO 22 | I2C SCL (Arduino Standard) | I2C SCL |
| TX0 | J2-4 | GPIO 1 (TX0) | USB TX | - |
| RX0 | J2-5 | GPIO 3 (RX0) | USB RX | - |
| 21 | J2-6 | GPIO 21 | I2C SDA (Arduino Standard) | I2C SDA |
| GND | J2-7 | GND | Ground | GND |
| 19 | J2-8 | GPIO 19 | - | - |
| 18 | J2-9 | GPIO 18 | - | - |
| 5 | J2-10 | GPIO 5 | Strapping pin; 10k Pull-Up on ESP32 DevKit V4 | (DHT In) |
| 17 | J2-11 | GPIO 17 (TX2) | - | - |
| 16 | J2-12 | GPIO 16 (RX2) | - | - |
| 4 | J2-13 | GPIO 4 | User Button | USER-BUTTON |
| 0 | J2-14 | GPIO 0 | Strapping pin, 10k Pull-Up; Button on ESP32 DevKit V4, closing to GND | - |
| 2 | J2-15 | GPIO 2 | Strapping pin; Onboard LED on ESP32 DevKit V4 | Onboard LED |
| 15 | J2-16 | GPIO 15 | Strapping pin | MTDO |
| D1 | J2-17 | GPIO 8 (D1) | - | - |
| D0 | J2-18 | GPIO 7 (D0) | - | - |
| CLK | J2-19 | GPIO 6 (SCK) | - | - |
| Adafruit ESP32 Feather V2 Pin | Adafruit Feather V2 Pin Header | WROOM32 Pin | Notes | Usage |
|---|---|---|---|---|
| RST | J1-1 | RESET | The reset pin is used for the reset button, but can also be used standalone. Tie it to ground to reset the board. Pull-Up; Button on Feather V2; Active High | RESET |
| 3V | J1-2 | 3.3V | 3.3 V output | +3V3 |
| NC | J1-3 | - | Not Connected | - |
| GND | J1-4 | GND | Ground | GND |
| A0 | J1-5 | GPIO 26 (A0) | This is also DAC2. It uses ADC2 | I2S_CLK |
| A1 | J1-6 | GPIO 25 (A1) | This is also DAC1. It uses ADC2 | I2S_WS |
| A2 | J1-7 | GPIO 34 (A2) | It is input/ADC only. It uses ADC1 | LDR-ANALOG-IN |
| A3 | J1-8 | GPIO 39 (A3) | It is input/ADC only. It uses ADC1 | - |
| A4 | J1-9 | GPIO 36 (A4) | It is input/ADC only. It uses ADC1 | - |
| A5 | J1-10 | GPIO 4 (A5) | It uses ADC2 | USER-BUTTON |
| SCK | J1-11 | GPIO 5 | This is the SPI clock pin | (DHT In) |
| MO | J1-12 | GPIO 19 | This is the SPI Microcontroller Out / Serial In (MOSI) pin (Adafruit Feather V2 Schematic-Symbol is wrong! -> IO18) | - |
| MI | J1-13 | GPIO 21 | This is the SPI Microcontroller In / Serial Out (MISO) pin (Adafruit Feather V2 Schematic-Symbol is wrong! -> IO19) | - |
| RX | J1-14 | GPIO 7 | This is the UART RX (receive) pin | - |
| TX | J1-15 | GPIO 8 | This is the UART TX (transmit) pin | - |
| 37 | J1-16 | GPIO 37 | It is input/ADC only. It uses ADC1 | - |
| GND | J2-1 | GND | Ground; JST connector | GND |
| BAT | J2-2 | VBAT | This is the positive voltage to the JST connector for the optional lipoly battery | - |
| BAT | J3-1 | VBAT | This is the positive voltage from the JST connector for the optional lipoly battery | - |
| EN | J3-2 | EN | This is the 3.3V regulator's enable pin. It's pulled up, so connect to ground to disable the 3.3V regulator | - |
| USB | J3-3 | VBUS | This is the positive voltage to/from the USB-C connector if connected | VCC-PROTECTED |
| 13 | J3-4 | GPIO 13 | It uses ADC2; Onboard LED | MTCK and Onboard LED |
| 12 | J3-5 | GPIO 12 | It uses ADC2 | MTDI |
| 27 | J3-6 | GPIO 27 | It uses ADC2 | LV-DATA-OUT |
| 33 | J3-7 | GPIO 33 | It uses ADC1 | I2S_Data_IN |
| 15 | J3-8 | GPIO 15 | It uses ADC2 | MTDO |
| 32 | J3-9 | GPIO 32 | It uses ADC1 | Test Pin |
| 14 | J3-10 | GPIO 14 | It uses ADC2 | MTMS |
| SCL | J3-11 | GPIO 20 (SCL) | I2C clock | I2C SCL (Adafruit Feather V2 Schematic-Symbol is wrong! -> IO22) |
| SDA | J3-12 | GPIO 22 (SDA) | I2C data | I2C SDA (Adafruit Feather V2 Schematic-Symbol is wrong! -> IO23) |
The following table shows the strapping bit status on the ESP32 DevKit C V4 board. See also ESP32 series datasheet chapter 2.4
| Pin | Default | Function 1 | Function 2 |
|---|---|---|---|
| Voltage of internal LDO (VDD_SDIO) | |||
| Pin | Default | 3.3 V | 1.8 V |
| GPIO 12 (MTDI) | Low | Low | High |
| Result: 3.3 V |
| Pin | Default | Function 1 | Function 2 |
|---|---|---|---|
| Booting mode | |||
| Pin | Default | SPI Boot | Download Boot |
| GPIO 0 | High | High | Low |
| GPIO 2 | Low | Don't care | 0 |
| Result: SPI Boot |
| Pin | Default | Function 1 | Function 2 |
|---|---|---|---|
| Enabling/Disabling debugging log print over U0TXD during booting | |||
| Pin | Default | U0TXD Toggling | U0TXD Silent |
| GPIO 15 (MTDO) | High | High | Low |
| Result: U0TXD Toggling |
| Pin | Default | Function 1 | Function 2 | Function 3 | Function 4 |
|---|---|---|---|---|---|
| Timing of SDIO slave | |||||
| Pin | Default | Falling-edge Sampling | Falling-edge Sampling | Rising-edge Sampling | Rising-edge Sampling |
| GPIO 15 (MTDO) | High | Low | Low | High | High |
| GPIO 5 | High | Low | High | Low | High |
| Result: Rising-edge Sampling |
GPIOs 34 to 39 are input only pins. These pins don’t have internal pull-ups or pull-down resistors. They can’t be used as outputs, so use these pins only as inputs.
ADC2 is used by the Wi-Fi driver. Therefore the application can only use ADC2 when the Wi-Fi driver has not started. See Analog to Digital Converter.
| Pin | Function |
|---|---|
| MTDI (GPIO 12) | Test Data Input |
| MTCK (GPIO 13) | Test Clock |
| MTMS (GPIO 14) | Test Mode Select |
| MTDO (GPIO 15) | Test Data Output |
See ESP-PROG.
The LED matrix consists of 8 x 32 WS2812B LEDs. Each LED has a max. current of 60 mA, which would result in a max. power consumption of 5 V / 15.36 A. The flexible LED panel matrix would be damaged with this high nominal power consumption, therefore it shall be limited to 5 V / 4 A.
Input voltage level:
- High - Min. 0.7 * VDD
- => 0.7 * 5 V = 3.5 V
- Low - Max. 0.3 * VDD
- => 0.3 * 5 V = 1.5 V
The i/o pins of the ESP32 are running with a 3.3 V level, which could cause a problem in detection a high! Therefore the level must be shifted from 3.3 V to 5V.
The following table shows the output voltage, generated by a LDR like the GL5528 and a 1 k resistor. Both assembled as voltage divider.
| Ambient light | Ambient light | Photocell resistance | LDR + R | Voltage across R |
|---|---|---|---|---|
| Moonlit night | 1 lux | 70 kΩ | 71 kΩ | 0.046 V |
| Dark room | 10 lux | 10 kΩ | 11 kΩ | 0.3 V |
| Dark overcast day / Bright room | 100 lux | 1.5 kΩ | 2.5 kΩ | 1.32 V |
| Overcast day | 1000 lux | 300 Ω | 1.3 kΩ | 2.538 V |
| Full daylight | 10,000 lux | 100 Ω | 1.1 kΩ | 3.0 V |
If you have further ideas or you found some bugs, great! Create a issue or if you are able and willing to fix it by yourself, clone the repository and create a pull request.
The whole source code is published under the MIT license. Consider the different licenses of the used third party libraries too!
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, shall be licensed as above, without any additional terms or conditions.