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Turn on/off flash on Sunmi L2s PRO

I need a way to turn off the flash of the Sunmi L2s PRO.

By "flash", I mean the light at the top of the device, next to the laser barcode scanner (I do not mean the torch at the back of the device):

Sunmi L2s Pro Top View

According to the Sunmi support, that is not possible. But the demo app which is shipped with the device has a setting which can enable or disable the flash, so there must be a way. But it seems like it is a private API.

Does anyone know how to toggle the flash or how I could reverse-engineer the demo app or "intercept" system calls etc. to find out how it is done?

Solution

  • The only two official methods to achieve what you want is by either pushing the setting from partner.sunmi.com web panel or through the scanner configuration (which you have called a demo) application.

    As you correctly assume, there is a third - a bit more unofficial and not documented way - which I, as a person who already disassembled and reverse engineered the scanner service on Sunmi devices - discovered.

    Just keep in mind that this is an unofficial API, that may stop working in the future. At this moment it works at every device I have tested (V2 Pro, V2s, V2s Plus, L2K, L2Ks, L2s and L2H), but it is not a guarantee.

    To use it follow the steps:

    1. Add the Sunmi scan head AIDL to your project according to Sunmi documentation.
    2. To IScanInterface.aidl add the following line before closing curly bracket: void sendCommand(String str) = 5;
    3. In your code (after you have bound the scanner service according to documentation) call the sendCommand with the parameter of either scan00000107=1; to enable or scan00000107=0; to disable flash control.

    With this API you can change all options of scanner configuration. There is also a second private method to query for current scanner configuration. In the future I will publish everything what I have learned during reverse engineering scanner service in the form of a generic Android library, but until that will happen, you can refer to my capacitor.js plugin, where you could find the control codes for rest of the settings if you want.