The Wio Extension - RTC is an extension board for Wio LTE. With Wio Extension - RTC, you can extend runtime of battery operated ( Internet of ) Things so easily.
Wio Extension - RTC has NXP PCF8523 Real-Time Clock (RTC), and PCF8523 control the power supply for the USB connector. When the power supply to Wio boards ( 1. USB in the picture above ), the standby current of whole system is less than 1 uA.
The sample code for Wio Extension - RTC works on Wio LTE and its Seeed Japan office software library for Arduino.
Open your Arudino IDE, click on File > Preferences, and copy below url to Additional Boards Manager URLs.
http://www.seeed.co.jp/package_SeeedJP_index.json
Click on Toos > Board > Board Manager, and enter Wio to the text box.
Click Seeed STM32F4 Board(JP mirror) by Seeed K.K. then an Install button appear, click on it to finish the step, this process takes about 5 minutes to half an hour, which depend on the speed of your network.
Click on Tools > Manage Libraries, and enter Wio to the text box.
Click Wio LTE for Arduino by Seeed K.K. then an Install button appear, click on it to finish the step.
Connect Grove - Buzzer or Grove - Red LED to D38 of Wio LTE.
Unzip the sample sketch, and open wiortc-sample.ino with Arduino IDE.
As you can read from the sample sketch, Wio Extension - RTC set to shut down the system for 30 sec on
RTC.SetWakeupPeriod(BOOT_INTERVAL);
and then set to shut down the whole system on
RTC.Shutdown();
When you use mobile battery as the power source of the system, you need to choose non smart power bank. Typical mobile battery have automatic power off function. And the battery shut off the power supply itself when Wio Entension - RTC enters stand-by, since its stand-by current less than 1 uA and it's too weak for the threshold of the battery.
Since Wio Extension - RTC just controlling USB power supply set from I2C, you can use this board to manage the power supply almost for every MCU boards powering from USB.