Introduction: Smart Messenger Bag With Wireless Charging

We will be making a smart leather messenger bag that features wireless charging and a Bluetooth strap that pairs with your phone and vibrates when receiving texts or phone calls


Arduino nano

coin cell vibrator

hc-05 Bluetooth module

3.7v lipo baattery

tpc4056 charging module

spst switch


messenger bag or leather to make one

Step 1: Cut Leather for Strap Pad

cut two pieces of 3.25" x 9" leather for the strap. I am using 7oz natural veg tanned leather.

Step 2: Solder Components

cut 4 pieces of ribbon cable in half. attach the cable connectors to the hc-05 module and solder the other ends to the Arduino. The pin configuration can vary, this is just how I did and it matches the provided Arduino code

vcc to 3.3v

ground to ground

txd to d10

rxd to d12

solder ground (blue wire) of vibrator to ground of arduino and positive(red) to A5

solder positive and ground battery wires to positive and ground battery out pins on tp4056

solder ground output of tp4056 to ground in arduino. then solder positive output of tp4056 to switch and switch to 5v on arduino

You will also likely need to replace the rprog resistor on the tp4056 to make sure the appropriate current is applied when charging the lipo battery. google tp4056 charging current to learn more

Step 3: Glue Components to Strap

glue the soldered components in between the holes in the strap. I used hot glue and small dabs of super glue. be careful with the super glue as it hardens leather easily.

Step 4: Upload Code to Arduino

The code can be found here:

Step 5: Test Circuit With Bluetooth Terminal (optional)

you can download Bluetooth terminals from the app store. we will test using the terminal to make sure the arduino is working without having to worry about the app we will be making causing any potential problems. send 0 to test the text vibration and 1 to test the phone call.

Step 6: Download App to Phone

the app was made using MIT app inventor. it can be found here:

you can drag and drop the file into your phone. You then will likely need to change app instillation permissions to install it from wherever you have placed it in your phone. Once the app is installed you can test it by opening the app, switching on the strap and emailing yourself a text and or use an additional phone to call the paired phone.

Step 7: Leather Electronics Cover

glue a thin piece of leather over the electronics. glue three of the edges to the strap and leave the edge covering the charger and switch open. Adding the cover will allow the strap to slide much easier through the strap pad without catching the electronics.

Step 8: Glue and Sew Strap Pad Together

glue the two strap pad pieces together and sew the edges. I have used a saddle stitch.

Step 9: Wireless Charging Bag

Next we will cover how to mount a wireless charging unit to the messenger bag

Step 10: Strip Wireless Charging Unit

purchase a wireless charger and remove it from its plastic casing. Alternatively you could opt to try and connect the charger directly to the bag as is. I used an Anker circular wireless charger.

Step 11: 3d Print Charger Case.

3d print the charger case pieces and glue them together with the wireless charging unit.

The 3d print files can be found here:

The case fits my galaxy s7 and should fit similar sized phones.

I chose to use clear filament for the charger cover so the blue led can be seen when charging

Step 12: Run Cables

cut slits in the back of the two front pockets of your messenger bag and feed the charger cable between them.

Step 13: Sew Charger to Bag

use the holes in the 3d printed case to sew it to the bag inside the pocket. Plug the charger into a power bank and test it out.

Step 14: Assemble the Rest of Bag

Either sew the rest of your bag together or sew any fixes in the messenger bag you purchased and you are all done!

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