pierce 2.0

pierce 2.0 is a split modular wireless / semi-wireless 36 key column staggered keyboard. The design is inspired by Corne with more pinky stagger as well as only using 1u keycaps. It is possible to build a wireless version or a semi wireless version. If building the wireless version an additional reciever dongle is required. In the semi wireless version the wired half is also acting as a reciever for the wireless half. Both versions have full QMK support.
Supported switches: MX, Choc V1, Alps

The semi wireless version has a built in reset circuit for connecting a PS/2 pointing device.

There are 3 different PCBs: wireless (reversible), wired (right) and reciever.

A programmer is necessary to flash the wireless modules. A cheap option is getting an ST-Link V2 clone from ebay.

Bill of materials

Wireless

Qty	Item	Comments
2	Pierce 2.0 wireless PCB
1	Pierce 2.0 reciever PCB
1	Pro micro or equivalent
2	Keystone 3034 Coin cell battery retainer	SMD
2	2032 3.3V Coin cell battery
3	YJ-14015 / Core51822 (B)
3	1x4 pin Right-angle 2.54 mm header	For programming RF modulules. Optional, temporary soldered wires works fine
2	4.7 kΩ resistor	SMD 1206
1	1117 3.3 V regulator	SMD SOT-223
1	THT momentary switch	2 pin THT 6 mm

Semi wireless

Qty	Item	Comments
1	Pierce 2.0 wireless PCB
1	Pierce 2.0 wired PCB
1	Pro micro or equivalent	Elite C recommended if using trackpoint. (Pin D5 broken out)
1	Keystone 3034 Coin cell battery retainer	SMD
1	2032 3.3V Coin cell battery
2	YJ-14015 / Core51822 (B)
2	1x4 pin Right-angle 2.54 mm header	For programming RF modulules. Optional, temporary soldered wires works fine
2/4	4.7 kΩ resistor	SMD 1206, 4 if using trackpoint, otherwise 2
1	1117 3.3 V regulator	SMD SOT-223
1	THT momentary switch	2 pin THT 6 mm
1	100 kΩ resistor	SMD 1206 Only for trackpoint
1	2.2 uF capacitor	SMD 1206 Only for trackpoint
1	Trackpoint module	R61 recommended, Only for.. well..

Build instructions

Soldering

The soldering is pretty straight forward and it should be obvious what component goes where. If you haven't soldered SMD components before I recommend watching a youtube tutorial or two beforehand. I suggest adding a bit of solder to the middle pad for the battery holder.

Flashing wireless modules

The following instructions is for using an ST-Link V2 clone and Windows.

1. Download and install OpenOCD from https://openocd.org/ and drivers for the programmer from https://www.st.com/en/development-tools/stsw-link009.html

2. Create a file called 'openocd.cfg' in the bin folder where you installed OpenOCD with the following content:

    #nRF51822 Target
    source [find interface/stlink-v2.cfg]
   
    transport select hla_swd
   
    set WORKAREASIZE 0x4000
    source [find target/nrf51.cfg]
   

3. Copy the relevant firmware .bin file to the bin folder where you installed OpenOCD

4. Connect the 4 pins SWCLK, SWDIO, GND and 3.3 V on the ST-Link V2 to the matching pad on the PCB and the ST-Link to the computer

5. Open a command prompt, navigate to the bin folder mentioned above and enter:

    openocd.exe -f openocd.cfg
   

6. Open another command prompt and enter:

    telnet localhost 4444
   

You should now be connected to the programmer. Enter the following commands to flash the firmware:

halt
nrf51 mass_erase
program <firmware_file_name>.bin
reset

That's it! You should now have a working pierce keyboard.

Plates

These need some work

I have included files to 3D print bottom plates and switch plates (only for alps for now). The idea of the screwless bottom plates is to use a friction fit, but I'm not sure how well the current version fits.