uPesy ESP32 Wrover DevKit
La carte uPesy ESP32 WROVER DevKit est basée sur un ESP32. Cette carte peut être mise sur une breadboard facilement car les 2 côtés de la carte sont accessibles pour mettre des fils sur la breadboard.
Note
The board has 4 MB of additional RAM . Indeed, most ESP32 boards are based on a ESP-WROOM-32 module while this board is based on a ESP-WROVER-B module. The 2 modules are very similar and are programmed in the same way: the only difference between the 2 is the addition of an external RAM for the ESP-WROVER-B module.
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ESP-WROOM-32 |
ESP-WROVER-B |
|---|---|
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512 KB of RAM |
512 KB of RAM + 4 MB of PSRAM |
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See also
To understand what PSRAM is and how to use it, see Use PSRAM
Pinout
Full version
Note
VP, VN, 34, 35
pins, i.e. GPIO36, GPIO39, GPIO34, GPIO35 pins can be used
only as input
.
They also do not have internal pullup resistors
(impossible to use
pinMode(36,
INPUT_PULLUP)
).
Important
Unlike Arduino boards, the pin number of the SPI, I2C, I2S, SD shown in the pinout is the default and can be changed. For example, instead of choosing VSPI on pins 23, 19, 18, 5 we can put it on pins 32, 33, 25, 26.
Features
- The technical characteristics of the boards are as follows:
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Processor: Xtensa Dual-Core 32-bit LX6 clocked up to 240 MHz
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Wi-Fi (802.11b /g/n) and Bluetooth 4.2 / BLE
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RAM: 520 KB of internal SRAM and 4 MB of external PSRAM
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4 MB of Flash (external)
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Different states to limit energy consumption (Modem Sleep, Light Sleep, Deep Sleep, Hibernation)
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Hardware cryptographic acceleration for AES, RSA, SHA2
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Usage recommendation
Pin voltage tolerance
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The ESP32 is a microcontroller that operates in 3.3V. The logic levels are therefore 0 and 3.3V and not 0 and 5V. This means that the output voltage of the GPIO pins is 3.3V and the input voltage must not exceed 3.3V. GPIO pins are not designed to have logic levels of 5V .
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The voltage measured by the Analog to Digital Converter must not exceed 3.3V(and not negative of course).
Note
Most modules / sensors can operate with 3.3V logic levels, but if this is not the case, level shifters (or possibly a voltage divider bridges) will be needed to switch from 3.3V to 5V and vice versa.
Warning
Since the ESP32 was not designed to receive 5V on these GPIO pins, the ESP32 can be damaged if they are longly exposed to this voltage.
Power the uPesy board
- There are several ways to power the board:
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The easiest way is by USB in 5V, by connecting the board to a computer or an external powerbank. You can then use the 5V and 3.3V pin to power a circuit.
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Alternatively, the board can be powered directly, by setting a voltage of 5V on the pin VIN by an external power supply and connecting the ground of the power supply to the ESP32 GND pin. The voltage on the 5V pin is that of the external power supply , the voltage on the 3.3V pin is 3.3V.
Warning
The input voltage on the VIN pin must be between 4.5 and 9V to avoid overheating (and potentially destroying) the 3.3V regulator on the board.
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The first 2 methods can be used at the same time : Have an external power supply connected to the VIN pin while having the board connected to the computer (the 2 grounds must be connected) . This is very convenieent for communicating with the Arduino IDE serial monitor while having the ESP32 powered by another external electronic circuit.
- It works as follows:
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If VIN < V_USB, with V_USB = 5V then the USB will be primarily used to power the ESP32.
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If VIN > V_USB, then the external power supply will be mainly used to power the ESP32.
Hint
This operation is normally safe on the uPesy board due to the 2 protection diodes that prevent back current to the power supplies. The vast majority of other ESP32 cards do not have these protections! Care must also be taken in this power supply mode to avoid irreversible damage to the ESP32 board and / or the computer’s USB port and / or the external power supply in the event of an error.
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The ESP32 can also be powered from the 3.3V pin with an external power supply even if it’s not recommanded . However, the 5V pin cannot be used.
Warning
The voltage must be around 3.3 V (3V-3.6V) otherwise the ESP32 may be damaged or destroyed.
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