Remote “ON STAGE” LED sign

How to remotely switch a LED sign via Bluetooth Low Energy @ 0.4mA standby current.


I had the issue at home with a wife at parental leave and a child to actively show when I’m not available. In theory I have my separation and the respect to have my room for doing my daily work in my home office. But sometimes there is the need I’m available for short questions or a short hug by my wife or child.The remote LED sign helps me to stay at my desk and to shortly change my status by iPhone or my business Mac.

The idea was to use BLE while it has the advantage of very low power consumption during standby but also offers a standard every smartphone and newer computer can talk to.

I’m in the lucky position to have an iPhone and a Mac, so the library for using BLE can be done once.



Simple Setup

The base is an “ON STAGE” LED sign powered by 2x AA 1.5V batteries. The connection of the LED sign has to be changed, so it matches to the following schematic by adding a HM-10 BLE module:

Connect to the HM-10 module via serial converter with 9600,8,N,1. (some configurations are 115200 baud)

Sending AT+VERS? or AT+VERR? should generate the answer HMSoft V540. If not, the firmware has to be updated.

As next the module has to be changed to be accessed by BLE:

AT+MODE1 // makes it possible to receive AT commands via BLE
AT+PWRM0 // Activates 0.4 mA unconnected, 8 mA connected
The software will send following commands:

AT+PIO20 // turn off the PIO2 GPIO, so LED will turned off
AT+PIO21 // turn on the PIO2 GPIO, so LED will turned on

You can use the iOS App provided in the Apple AppStore:

Find the BLE library for iOS and macOS and more at GitHub:

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