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Assembly

Once you received all parts, you can start assembling the block.

Important

The steps and component names are based on the rev4.1 board. If you have a different one, make sure to check the schematic.

PCB

Besides the components, you will also need a soldering iron, solder, and additional tools like tweezers.
Many of the components are surface mounted (SMD), feel free to use heat reflow or other methods, but I found that using a fine soldering iron tip works fine as well.

You can use the Schematic (PDF) as a reference for components.

Tip

You can follow the assembly order listed below, to validate the components as you go along

Main Controller

We’ll start by soldering on the ESP32S3 WROOM (U3).

Green PCB clibbed onto soldering stand with an ESP32S3 module soldered to it. The other solder pads are still exposed.

Afterwards, we’ll add the USB408 USB-C port (J3) and both the boot and reset button assembly (SW3, SW4, C4, C5, R7, R8).

The same PCB from the same side at a slightly different angle, showing a USB-C port, two buttons and some other components being populated.

Tip

If you want to ensure the ESP is functioning properly, you can hook up the 3V3 and GND lane, which is exposed through the display interface to an external powersupply and connect a USB cable between your computer and the device. You should see that the device is showing up in lsusb as an Espressif device Which you can control using the Boot and Reset buttons.

Power Management

With the ESP, being the most complicated part, out of the way, we can move on to the on-board power-management.
This includes the voltage converter MIC5504 (U1), battery charge controller STC4054GR (U2), battery controller port JST PH-K (J1) and R2, C2, R3, R6, C1, C2, C3,.

Other side of the PCB, with a battery connector and small chips installed

Tip

To confirm if everything is working as expected you can connect the battery to the battery connector and plug the device back into your computer. It should show up the same way it did before, but without requiring an external power source.

Required Peripherals

With the base system done, we can move on to the required peripherals.

Before hooking up the display, I would recommend unsoldering the display pin header, to make more space in the upper part of the case, where the battery will be stored.
After unsoldering it, solder on four wires (roughly 4cm long) and hook them up to the top of the PCB (J2).

Closeup of the Display board back. The header pins have been cut off close to the PCB. Four wires have been connected to the pins

Tip

If you are impatient, you can already test the display by flashing the firmware onto the device and powering it up / resetting the device (See below)

You will also want to solder on both limit switches (SW1, SW2), as they are required to turn on the block.
Make sure to bend the metal plate on the switches about 90 degree at the midpoint, to give the arms something to interface with. Feel free to experiment with different angles for different button push-back force.

Closeup of the Precious Blocks PCB with two limit switches installed. The switch arms have been bent at the mid-point into roughly 90 degrees angle pieces.

Tip

If you’ve already flashed the firmware, you should now be able to wake the block from sleep

Additionally, you should hook up the vibration motor to the pins on the bottom.

Precious Block PCB with the required components installed. Some copper plates are still unpopulated, but the battery has been connected and the motor and display wires soldered to the pins on the PCB.

Tip

When you wake the block, by pressing both arms the motor should vibrate indicating that it is working properly

Flashing the firmware

You should now be able to flash the firmware onto the PCB in download mode.
Note that you have to hold the Boot button, while pressing the Reset button to enter the download mode, when a battery is connected.

If you flash the block for the first time, espflash might complain that the block is stuck in download mode and it is waiting for a response.
In this situation, check if the firmware flash process was successful, and manually reset the block.
This should not be required from now on.

Once you restart the block, you should see the sleeping eyes shown on the display and be able to interact with it using the arms.

Finally, you can solder on the external clock module, by soldering on the PCF8523T (U4), the oscillator (Y1), and the coin cell battery holder (BT1).
You also have to add a coin cell battery (CR1220) as the device won’t turn on otherwise.

You should also solder up the resistors required for battery charge monitoring (R1, R4, R5).

Closeup of the top-side of the PCB. A coin cell battery holder and a couple of resistors have been installed in the previously unpopulated slots

Important

Furthermore, you should hook up an external wifi antenna to the ESP antenna port if you want to use WiFi.
And make sure the Li-Ion battery is connected.

This should leave you with a fully working PCB, ready to be mounted inside the case

Case

Both the front and back have recesses to fit four magnets.
The magnets are used to align the two shell pieces and ensure they stay together.

You can use instant glue to glue the cubes into the front of the case.
Afterwards match the magnet orientation for the back, so the front attracts the back. And glue them in place by pushing them into the recess on the back using a wooden rod (or a different non-magnetic rod).

Tip

You should do a test fit after the glue dried to make sure you got the orientations correct (trust me).
If one of the magnets is wrong, use a pair of parallel pliers (or comparable) to remove it from the front part by wiggling it.

With the magnets in place, you can glue the vibration motor into the recess in the bottom of the back case.
You can also reconnect the battery (if you removed it) and use some sticky-foam-tape to glue it into the box on the top.
Afterwards, slide in the pcb into the back of the case, making sure to align the USB port on the back.

Top down view of the back of the Precious Block case. The PCB has been slotted into the bottom of it and the battery glued into the top section. The antenna is running from the ESP to right below the battery. The display is placed next to the case on the desk, connected to the PCB with four cables

Tip

You can stick the WiFi antenna to the LiPo using electrical tape, it should perfectly fit into the top, although you might have to bend the cable a little to allow the front to go on properly

To install the display, push one side into the recess and slowly press down on the opposite side to snap it in place.

Display board slotted into the front case. Its top is facing towards the top of the case and only the right part is fully pressed into the recess. The left part of the display board is lightly placed onto the guide rail, leaving a small space between the front and the display board. Same camera shot as before, but the left hand side of the display board has been pressed down to slot into the front recess.

Tip

You can remove the display by applying even pressure (i.e. using your thumb) to it from the front of the case. Make sure not to overdo it though, as you might crack the fragile display components.

Before sliding on the front, push the arms onto the pins on the back, making sure the arms interface with the limit switches on the PCB.
Now, push on the front case and make sure the PCB fits into the PCB mount in the front half.

Lastly, you can push the lanyard wire through the hole on the top and fix it in place by looping it through itself.

Fully assembled apricot Precious Block sitting on the ledge of a wooden flower pot, in front of a cute sign. The plant in the pot has a bunch of tiny flower buds in a lighter apricot shade.

Note

That is it - you have fully assembled your own Precious Block

Enjoy 🌸