HackerBox 0125: Vitality

Welcome to HackerBox 0125. Explore wireless power transfer and the Qi open standard for inductive charging. Experiment with colorful, wireless LEDs. Assemble the Mochi Digital Companion as a fun virtual pet. Configure the ESP32-C3 Supermini development board for operation with the Arduino IDE. Provide the Mochi Digital Companion with a touch sensor for input, an OLED display and audio speaker for output. Provide Mochi with a rechargeable lithium polymer battery pack that can be charged over USB or using a wireless fast charge puck.

There is a wealth of information for current and prospective members in the HackerBoxes FAQ. Almost all of the non-technical support emails that we receive are already answered there, so we'd really appreciate it if you can take a few minutes to read the FAQ.

This Instructable contains information for getting started with HackerBox 0125. The full box contents are listed on the product page for HackerBox 0125 where the box is also available for purchase while supplies last. If you would like to automatically receive a HackerBox like this right in your mailbox each month, you can subscribe at HackerBoxes.com and join the party. Subscription members save at least $15 every month and automatically receive each new HackerBox shipped immediately off the production line.

A soldering iron, solder, and basic assembly tools are generally needed to work on the monthly HackerBox. A computer for running software tools is also required. Have a look at the HackerBox Workshops for tools and supplies along with a wide array of introductory activities and experiments.

The most import thing you will need is a sense of adventure, hacker spirit, patience, and curiosity. Building and experimenting with electronics, while very rewarding, can be tricky, challenging, and even frustrating at times. The goal is progress, not perfection. When you persist and enjoy the adventure, a great deal of satisfaction can be derived from this hobby. Take each step slowly, mind the details, and don't be afraid to ask for help.

WEAR SAFETY GLASSES WHEN SOLDERING, WHEN TRIMMING WIRE LEADS, OR WHEN CUTTING, DRILLING, ETC.

As if by magic, these coil-mounted LEDs are powered without any direct wire connection. Power delivery is supported through inductive coupling. The large outer coil is driven by an AC waveform. The smaller coil of each LED receives power coupled through the field generated by the larger coil. Together, the two coils operate is if they are each halves of a traditional power transformer. More than meets the eye.

The video above illustrates interesting early developments in wireless power delivery. Members may recall leveraging one of the most common use cases for powering a circuit wirelessly in The RFID Lab: HackerBox #0117. A small number of those boxes are still available if you missed it.

Qi (pronouced CHEE) is an open standard for inductive charging developed by the Wireless Power Consortium. It allows compatible devices, such as smartphones, to receive power when placed on a Qi charger. The Chinese name Qi means "vital energy".

Wireless Power Transfer is a generic term for transmitting energy by means of electromagnetic fields. In general, a wireless power system consists of a "transmitter" device connected to a source of power such as a mains power line, which converts the power to a time-varying electromagnetic field, and one or more "receiver" devices which receive the power and convert it back to DC or AC electric current which is used by an electrical load.

The Mochi Digital Companion is a DIY virtual pet gizmo. A number of open source projects have popped up inspired by the commercial product named Dasai Mochi. The kit implementation presented here is closely inspired by the ESP32-based huykhong mochi project.

Mochi, in addition to referencing a rice-based dessert, is a slang term for a cute, lovable, little friend.

Mochi Digital Companion Kit Components:

1. Four Exclusive Mochi Companion PCBs
2. ESP32-C3 Super Mini Development Board
3. 1.3 Inch OLED I2C Display Module
4. TTP223 Capacitive Touch Module
5. TP4056 1A Lithium-Ion Battery Manager Module
6. Wireless Power Receiver Module with Coil
7. 8 Ohm Audio Speaker
8. SMD Slide Switch
9. Five 1x6 Pin SMD Female Header Sockets
10. 1x40 Pin Male Header Strip

Optionally, you can add a Rechargeable Lithium Polymer battery pack. We suggest a 500mAh 503035 which fits neatly inside the unit, but any LiPo around that size should work fine. The 503035 LiPo is available from DigiKey, Amazon, and various other sources.

For the Mochi Digital Companion project, we'll be leveraging the ESP32-C3 Supermini Development Board.

Before doing any soldering...

Power up the ESP32-C3 development board and verify the tool chain.

When power is first applied to the board using a USB-C cable, the Red Power LED (PWR in the image) will illuminate and the Blue Onboard LED (IO8 in the image) may blink.

Install the Arduino IDE, if necessary.

Within the IDE, use the Boards Manager to search for ESP32 (by Espressif Systems).

Select that board package and hit install.

Select: Tools > Board > ESP32 > Nologo ESP32C3 Super Mini

Open the example sketch:

File > Examples > Basics > Blink

Program the sketch to the board.

If the programming process has a connection error, force the development board into bootloader mode:

1. Hold down the BOOT button
2. Press the reset (RST) button
3. Release the RST button
4. Release the BOOT button
5. Try to program the sketch again

If everything is in order, the blue onboard LED (GPIO 8) will blink. If it was already blinking prior to this, experiment with changing the values in the delay() calls to alter the timing of the blink pattern.

After programming, you may need to reset the development board (press the RST button) to force a restart.

Some interesting thoughts on the CA-C03 ceramic chip antenna used on this development board.

Locate the Exclusive Mochi Companion PCB with the large letter L (for LEFT).

Using the image above as a guide...

Solder TWO 1x6 Pin SMD Female Header Sockets into place. Be sure to keep the plastic portion of each socket aligned within the white silkscreen rectangles on the PCB.

Position the ESP32-C3 Super Mini Development Board as shown. Be sure to have the USB-C socket extend just beyond the edge of the PCB.

After Soldering the ESP32, connect USB power and be sure that the MCU boots up and returns to running the blink.ino firmware that was previously programmed onto the ESP32.

(Optional) Place the sticker with the little space man onto the reverse surface of the PCB as shown.

Locate the Exclusive Mochi Companion PCB with the large letter R (for RIGHT).

Using the image above as a guide...

Solder TWO 1x6 Pin SMD Female Header Sockets into place. Be sure to keep the plastic portion of each socket aligned within the white silkscreen rectangles on the PCB.

Position the speaker in the white circle between the 1x6 headers as shown, facing out through the holes, and rotated such that the terminals of the speaker are adjacent to the SPKR pads on the PCB.

Affix the speaker into this position with hot glue, CA glue, or some other craft adhesive.

Using two small pieces of wire and solder, jumper between the terminals of the speaker and the SPKR pads on the PCB. If you don't have any bits of hookup wire lying around, use some wire trimmed from the battery or from the wireless power receiver coil, both of which will be addressed while assembling the (B)OTTOM PCB.

(Optional) Place the sticker with the circular void onto the reverse surface of the PCB as shown.

Locate the Exclusive Mochi Companion PCB with the large letter T (for TOP).

Using the image above as a guide...

Solder the one remaining 1x6 Pin SMD Female Header Socket into place. Be sure to keep the plastic portion of the socket aligned within the white silkscreen rectangle on the PCB. The opening edge of the socket should line exactly against the edge of the PCB.

Cut two strips of six male header pins.

For each of the two male headers, insert the short side of the header through the PCB from the side with the SMD female header. On the other side (with the HackerBox logo), solder the pins to the PCB while holding the header pins as straight and perpendicular to the PCB as possible.

Position the TTP223 Capacitive Touch Module onto the same side of the PCB as the female header. Place the touch module flat against the PCB with the components face out.

Cut a strip of three male header pins and insert the pins through the touch module with the plastic insulator on the sensor side.

Trim the three pins flush against the other side of the PCB (the side with HackerBox logo).

Solder each of the three flush-cut pins into the PCB hole surrounding each respective respective pin.

Turning back to the touch sensor side, remove the plastic insulator from the three pins.

(Optionally) cut most of the three pins off nearly flush against the touch sensor module.

Solder the three pins to the touch sensor module.

Locate the Exclusive Mochi Companion PCB with the large letter B (for BOTTOM).

Using the image above as a guide...

Position the TP4056 battery manager module flat against the PCB on the side with the large B.

Cut two pins from the male header strip and place them each through the front corners of the battery manager module on either side of the USB-C port and through the "B" PCB as well.

Similar to the process used with the touch sensor, solder the side of the header pin without the plastic insulator, and then remove the insulator from the other side and solder there as well.

Solder the OUT+ and OUT- through-holes of the battery manager module onto the PCB pads below. This is most easily accomplished by inserting the tip of the soldering iron into, or against, each hole and applying a just enough solder to fill the hole up as it melts to the PCB pad beneath.

Unsolder the coil leads from the Wireless Power Receiver Module. Note which leads go to which module contact point.

Position the wireless power receiver module flat against the PCB next to the TP4056 battery manager module.

Solder the positive and negative through-holes of the wireless power receiver module onto the PCB pads below.

Affix the coil from the wireless power receiver module onto the reverse side of the "B" PCB. The circular backing plate of the coil may have a peel-off adhesive, or a bit of tape or hot glue may help. (Pro tip: Attaching the coil with a couple millimeters of "elevation" from the PCB can allow for easier wireless charging by ultimately positioning the coil closer to the external wireless charger. This additional elevation can be achieved by attaching the coil to the PCB with double-sided foam tape, a couple layers of looped tape, or an extra lumpy application of hot glue.)

Route the coil leads through the hole in the PCB, trim the leads to length, and use solder to reconnect the leads to the wireless power receiver module. Connect each lead to the same terminal that it was initially removed from.

Next, solder the SMD Slide Switch to the PCB. It may be oriented in either direction. It is not polarized.

Just as with the "T" PCB, provide two strips of six male header pins. Insert the short side of each header through the PCB from the side with the two modules such that the long pins extend from around the modules as shown.

If connecting a LiPo battery pack, trim its leads down to 4 cm and solder the leads to the B+ and B- terminals of the battery manager module. The red battery wire is generally positive (B+).

Arrange the four PCBs as implied by their names and plug the four 6 pin mating headers together.

Before turning on the power, double check the orientation using these pointers:

1. The female header just under the HackerBox logo is for the OLED display (the face) so that is the front.
2. The four big letters on the PCBs are on mochi's inside surfaces.
3. The four big letters are oriented towards the front (mochi's OLED face).
4. There are two USB-C ports at the rear of the mochi (opposite the OLED face).
5. Following anatomical convention, mochi's side panels are R (right) and L (left) from mochi's perspective, which will be opposite from observer's right and left while facing mochi's face to face.

Once the four PCBs are plugged together, plug the OLED display into the center four female sockets just under the HackerBox logo. To allow the OLED to rest flush against the mochi PCBs, remove the black plastic insulator from the OLED's header pins.

It's alive...

The USB-C port on the L panel (ESP32) is used for programming and communicating with mochi.

The USB-C port on the B panel (battery manager) is used for charging the optional LiPo battery.

To program mochi's ESP32, go to the huykhong mochi project, select English translation, and follow the Install button.

Explore mochi's various configuration options.

Fix mochi's face by changing "Screen type" to SH1106.

Wireless Vitality...

Power up the 15W Wireless Fast Charger Puck using the supplied USB-C cable. Place mochi on the puck. Slowly slide mochi until its bottom coil is closely aligned the center of the charger puck. At that point, an LED on the battery manager module (inside mochi) will illuminate indicating that wireless power is being coupled from the puck to mochi! If the red LED illuminates, the battery is charging. Alternatively, the blue LED indicates that the battery is "full" and charging is complete.

If the wireless charging process does not appear to be working, it might be that the coil leads got reversed during the disconnection/reconnection process.

Even more Vitality...

The 15W Wireless Fast Charger Puck can also be used to charge smartphones, earbuds, or other mobile devices equipped with the appropriate wireless charge receiver functionality.

Transistor–Transistor Logic meets RUN DMC. Whose house?

We hope you are enjoying this month's HackerBox adventures into electronics, computer technology, and hacker culture. We aim to curate a challenging and rewarding experience of learning through experimentation and exploration. Thank you for joining us on this journey.

Reach out and share your success in the comments below. Email support@hackerboxes.com anytime with questions or whenever you need some help.

Hungry for more? Surf over to HackerBoxes.com and join us as a monthly HackerBox subscription member. You'll get a cool box of hackable gear delivered right to your mailbox every month and you'll enjoy a generous member discount.

Please consider sharing this free Instructable with others who may be interested in learning about these subjects. Word of mouth advertising is the greatest compliment that we can receive. We sincerely appreciate your support.