@xsklero There's an example of a BLE server here: https://docs.pycom.io/firmwareapi/pycom/network/bluetooth/gattscharacteristic.html Whatever you try, if you have an issue, you need to be more specific. Tell us what code you are using and the exact issue you are facing.

@codemaniac64 Umm I'm not sure, do you have any debug visibility on your PSoC code? Seems like it's rejecting something. Can you see if the BLE connection is still up when you try the .write(b'x0f')? It really helps to have a BLE sniffer like this https://www.nordicsemi.com/eng/Products/Bluetooth-low-energy/nRF-Sniffer