The Lolin32 Lite development board uses a ESP32 microcontroller, has 4MB flash memory, and supports connecting an external LiIon/LiPo rechargeable battery. The battery can be charged through the USB-C connector. In combination with its small footprint, it is a good choice for use in portable devices.
High deep sleep power consumption makes this board not a good choice for battery-operated sensors designed to run continuously: a deep sleep consumption of >4.500uA is much higher than average boards (300-500uA), let alone power-optimized boards (12uA), and will drain batteries quickly. This board is a good choice for portable devices that you want to completely switch off when not in use, i.e. via a physical switch or a bistable electronic switch.
This board is officially retired by its manufacturer WEMOS since 2018, and is no longer referenced on their website. It is still a great board, and it is currently (2024) sold for extremely low prices (<€1.50). The currently sold version now has a USB C connector whereas the original version came with Micro USB.
You can view an archieved version of the Lolin Lite product page. The successor of this board is the WEMOS Lolin D32.
Overview
Lolin32 Lite is an excellent classic *ESP32S board with a small form factor while still exposing all important pins. It is retired, and meanwhile there are more modern and sophisticated microcontrollers and boards available. But not for a price of €1.50 per piece.
Pros and Cons
The things I like most about this board:
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Just Works: dependably switches in bootloader mode. It is very simple to use and to flash.
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Small and Complete: compared to the bulky ESP32 DevKit boards, this one is small, exposes all important pins, and fits in portable housings. It comes with an onboard LED: the schematics clarify that GPIO22 is sinking current; the other leg of the LED is connected to 3.3V. Thus, the LED is low active (on when GPIO22 is low):
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Built-in LiIon Battery Support: it’s easy to hook up a LiIon or LiPo battery and run this board on the go.
What I did not like:
- Unconventional I2C Pins: board uses non-standard I2C pins which requires you to change the default pins in sample code.
- High Deep Sleep Power Consumption: unlike Lolin32, this Lite board requires hefty 4.5mA quiescent current while in deep sleep. 100-300uA would be normal. So no good choice for always-on sensor projects.
- No Vin/5V Pin: this board is designed to be powered either by 5V USB, via 3V pin, or via LiIon battery. There is no Vin pin to supply external power from a power supply. Likewise, there is no built-in way to power 5V peripherals. You can of course solder your own 5V connection to the USB connector but that’s no fun.
I2C
This board does not expose the usual pins for I2C (21 and 22): pin 21 is not exposed, and pin 22 is used for the internal LED.
I2C is connected to pins 2 (SCL) and 15 (SDA). That is a bit unfortunate since pin 2 is a strapping pin.
Since ESP32 can map I2C pins to any other GPIO, if the default pins cause trouble, pin 23 (SDA) and 19 (SCL) might work better for you.
SPI
The board exposes the default SPI pins:
| Pin | Description |
|---|---|
| 23 | MOSI: master-out-slave-in |
| 19 | MISO: master-in-slave-out |
| 18 | SCK: clock |
| 5 | CS: chip select |
| 22 | WP: wrrite-protect (also internal LED) |
Specs
| Item | Description |
|---|---|
| Memory | external 4MB Flash |
| Clock Speed | 240MHz |
| Charging | 500mA charging current, TP4054 |
| Voltage Regulator | ME6211 |
| Power Consumption | 45.4mA (no WiFi), 130mA (WiFi), 4.5mA (deep sleep/hibernation) |
| Internal LED | GPIO22 |
| Battery | LiIon/LiPo 3.7V |
| Battery Connector | Micro-JST 2.0 PH 2-Pin |
| USB Connector | Micro-USB (older versions), USB-C (latest versions) |
| USB-to-TTL | CH340 |
| Size | 49.2x25.5mm |
| Weight | 6.6g |
Charging
Power can be supplied from a LiIon/LiPo via its JST 2.0 PH connector. The battery is charged when the board is connected to USB via a standard TP4054 charger IC:
Comparison Lolin32 Lite vs. Lolin32
The Lolin32 Lite development board is the smaller version of the Lolin32 development board. The latter has its JST 2.0 battery socket placed on the side rather than next to the USB connector.
The differences between Lolin32 Lite and Lolin32 are the smaller footprint of the Lite board, and as a consequence of its smaller size the lack of some pins: RX0, TX0, and 5V are not exposed. There is also just one GND pin (instead of five), and just one 3.3V pin (instead of three).
To further reduce the board size, it has a reset but no boot button. This turns out not to be a disadvantage though as the board reliably turns to firmware upload mode automatically when flashing it in Arduino IDE, platform.io, and ESPHome.
For unknown reasons, while the Lolin32 has excellent low deep sleep power consumption (around 130uA), the Lolin32 Lite (discussed here) required astonishing >4mA. Despite all efforts - using ext1 mode and hibernation, manually disabling I2C pullups, supplying power directly to the 3V pin - the quiescent current remained above 4.5mA. This indicates a serious hardware design flaw in which i.e. the battery charger or voltage regulator is consuming power while in deep sleep mode.
Lolin32 Lite specifically targets portable devices and focuses on a small footprint, rechargeable battery support (including charging), and use of power-efficient 3.3V components only. There is no 5V pin, and its GPIOs are not 5V tolerant.
The board receives power solely via a connected battery or its USB connector. While you can supply power via its 3.3V pin directly, this disables the built-in battery charger.
Lolin32 Lite should have more accurately be named Lolin32 Portable as it is just as powerful as Lolin32 and not at all a lite version, rather optimized for portable use.
When To Use
This is a relatively cheap yet solid board with many exposed pins at a small form factor. Thanks to its built-in LiIon battery support and relatively small size, it serves well in portable or solar-powered devices.
One important draw-back is its missing support for 5V peripherals. Another point worth consodering in battery-operated projects is its relatively high deep sleep power consumption. If you need to maximize battery life, you either look into the Lolin32 (without Lite) which uses just 70uA in deep sleep. Or you simply turn this board into a highly power-efficient solution (with only 130nA sleep current) by adding a bistable switch.
Materials
Lolin32 Lite Schematics
ME6211 Voltage Regulator
Lolin32 Lite eBook
HM4054H Charger
LTH7R Charger (Chinese)
LTH7S Charger (Chinese)
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(content created May 15, 2024 - last updated Oct 15, 2024)