Witty Pi 4 L3V7: RTC Relógio de Tempo Real e Gestor de Energia para Raspberry Pi

Witty Pi is an add-on board that adds realtime clock and power management to your Raspberry Pi. It can define your Raspberry Pi’s ON/OFF sequence, and significantly reduce the energy usage. Witty Pi 4 L3V7 is the new member of the fourth generation of Witty Pi, and it is designed to work with 3.7V Lithium (ion or polymer) battery (that’s what L3V7 stands for), and can be used as an UPS.

Witty Pi 4 L3V7 has these hardware resources onboard:

• Factory calibrated and temperature compensated realtime clock with ±2ppm accuracy.
• Dedicated temperature sensor with 0.125 °C resolution.
• AVR 8-bit microcontroller (MCU) with 8 KB programmable flash.
• DC/DC step-up (boost) converter that outputs up to 5V/3A.
• Charging manager that can charge battery with up to 1A current.

Witty Pi 4 L3V7 has very similar design with Witty Pi 4, however its DC/DC converter is a step-up (boost) converter, while Witty Pi 4 comes with a step-down (bulk) converter. Witty Pi 4 L3V7 also has charging circuit that can charge the battery.

Remarks: Witty Pi’s software is developed and tested under Raspberry Pi OS (the former Raspbian). If you want to use Witty Pi on other Linux distributions, you may not be able to install the software without error. This is due to the fact that different Linux distributions have different packages installed by default, and their default users may have different privilege settings too. You may need to modify the software installation script or even the software itself, however this will need you to have some knowledge of BASH programming.

Built-in Uninterruptible Power Supply (UPS) Functionality

Witty Pi 4 L3V7 has integrated the battery charging circuit and DC/DC boost converter on board, and it can be used as an uninterruptible power supply (UPS). Witty Pi 4 L3V7 can work with all chargeable Lithium Ion or Lithium Polymer battery that has nominal voltage of 3.7V (and full-charged voltage of 4.2V).

When 5V power supply is connected to the USB-C connector on Witty Pi 4 L3V7, it will take the priority to power the board with Raspberry Pi together. In the meantime, the battery is disconnected from the power rails and gets charged.

After 5V power supply is disconnected, the voltage of the battery will be monitored by Witty Pi 4 L3V7. Once the battery voltage drops under a preset threshold, Witty Pi’s software will perform a graceful shutdown and then cut the power of Raspberry Pi. By adjusting the low voltage threshold, you can decide when should the device shutdown before the battery is fully discharged.

Accurate Realtime Clock and ON/OFF Scheduling

The realtime clock (RTC) on Witty Pi 4 L3V7 has been calibrated in the factory and Witty Pi 4 L3V7’s firmware also makes temperature compensation for the crystal. This makes the RTC very accurate and the actual annual error is limited within ±2ppm. When your Raspberry Pi boots up, the time stored in the RTC will overwrite the system time. As a result, your Raspberry Pi knows the correct time even without accessing the Internet. You can schedule the startup and/or shutdown of your Raspberry Pi, and make it a time-controlled device. You can even define a schedule script to schedule complicated ON/OFF sequence for your Raspberry Pi.

Note: For more detailed information, please check this page