Making a Custom Pocket P.C. LoRa Antenna

Welcome to another update regarding Pocket P.C.’s development and production plan. We want to thank everyone for your patience and understanding. As you will read below, we have recently overcome a major hurdle regarding selecting and designing the right LoRa antenna.

There has been much testing of each and every component of the Pocket P.C. PCB and there have been many communications and in-person meetings with vendors to get support and clarification on product features.

This past month, we have also made some minor corrections to the PCB design and schematic. Once we have placed the order for the new sample PCBs, we will open source the latest design on GitHub.

The LoRa module communicates

We were able to successfully test the LoRa capabilities of Pocket P.C. w/ LoRa. Our tests showed that we were able to send data through multiple concrete walls in our office and from a 16-story window to the ground floor.

We have selected the RAK4200 LoRa module from RAKWireless. This module has the same specifications as the Murata module we originally selected however RAKWireless provides us with much better technical support and customer service that is invaluable during development and afterwards when you, the user, has questions about the module that we can’t answer.

The RAK4200 has a robust AT command set that allows you to easily join a LoRaWAN network or communicate peer-to-peer. You can read more about this module on their documentation page here:

By using the built-in Black Magic Probe, we were able to download the latest firmware available on their website and update the RAK4200 module immediately without any special tools besides the GDB software which will come pre-installed.

LoRa Antenna Efficiency Issues

Despite our initial successes with the LoRa module we found that during initial RF lab testing of the performance of the antenna the efficiency of the FR4 chip antenna that we selected was very low. This was determined to be due to the close proximity of the antenna to the LCD, which has a metal backing, and the structure of the enclosure itself. To resolve this issue a different type of antenna had to be selected and tested. We consulted with a few expert antenna engineers and performed software simulations with special software and found similar results to what we found in RF lab testing.

Fortunately, our antenna vendor proceeded to create a custom antenna for our device from scratch.

Here you can see that the antenna vendor’s engineers used copper foil to prototype various antenna designs. The antenna prototype pictured above provided the best efficiency.

After prototyping the antenna with copper foil, we had some samples made. On the left of the above photo is the sticker side of the sample antenna where you can see the antenna pattern and on the right is the connection side where there is an exposed copper area that connects to pogo-pins soldered on the PCB.

In order to test the new antenna our antenna vendor made some modifications to our existing PCB. Pictured above are the two pogo-pins that connect the main PCB to the antenna. One is the RF feed signal and the other one is ground. To design and develop a new antenna we removed the original antenna and scraped away the antenna pads and ground copper. We then drilled holes in the PCB so that the pogo-pins can be mounted. The RF feed pogo pin was then connected to the LoRa module via a coaxial cable with an ipex connector. In the final PCB, we will use the RF pad on the module and will not use a coaxial cable which should improve performance.

External LoRa connectors?

We’ve received some requests for the ability to connect an external LoRa antenna to Pocket P.C. w/ LoRa. We are evaluating how we can offer that capability. This would require a PCB mounted antenna and a hole in the case. We won’t be able to test the feasibility of an external antenna connector until after we enter mass production of the Wi-Fi/Bluetooth only version and the LoRa version with an internal antenna for those that opt for it.


  • We recently were able to get Ubuntu 18.04 booting on Pocket P.C.
  • The display backlight driver has recently been tested to work properly. (See below)
  • The touch driver has been tested but will require some more work to properly calibrate and improve responsiveness.
  • The display video driver development is put on hold until the next version of the PCB is assembled. It is estimated that it will require an additional 5-10 days to complete and work will resume once the new units are in our software developers hands.

PCB Updates

We added another communication bus (I2C) to the system controller from the main SoC so that it can have more insight into the operation of the entire system while performing its role as the keyboard controller over USB.

Shipping Update

As both versions of Pocket P.C., one with LoRa and one without both use the same PCB, the above issue with the antenna led to delays for both versions. As we have a clear path forward now, we will be ordering the next round of PCBs for another quick verification production run to prove the changes we made in the latest revision. This should take two additional weeks. With the most recent changes verified then we can start P.V.T. with mass production to follow soon after. Our current target for when we will be shipping is in June. We will be shipping the version without LoRa first to allow for any extra time that may be required for certifying the radios in the LoRa version.

Final Thoughts

With major development work being done, we will be focusing our efforts on the software offerings that will be available at launch. We will have a limited number of Pocket P.C. available in the next production batch that can be used for bring-up of new distributions. If anyone is interested in porting a Linux distribution that they are familiar with to Pocket P.C. please contact us. Also, please contact us if you are interested in using Pocket P.C. in a business or industrial setting, we can offer pre-production units for a limited-time product evaluation.

If anyone has contacted us and has not received a response, we apologize for the delay. We have been heavily involved in solving the remaining design issues so we can get Pocket P.C. into production. Please feel free to follow-up on your previous email to receive a quicker response.

Thank you everyone again for your patience and for being early supporters of Pocket P.C. We are excited to get your Pocket P.C. in your hands and see what you do with it.


Pocket P.C. Urgent Update Follow-up

You may have missed our previous email regarding the significant increase in the prices of components, plastics and packaging. If you did, you may miss the deadline for pre-ordering a Pocket P.C. before the prices increase. Not to worry! Because we did not have the opportunity to send a reminder update earlier, we are extending the deadline to order at the lower price until Sunday night 11:59 PM EST (UTC-5), March 21st, 2021.

If you want to read the original update, check out our previous blog post here:

Thank you for your continued support.


Pocket P.C. Urgent Update

Living in Shenzhen, China, has given me direct access to one of the largest electronic manufacturing hubs in the world.  Because of this, I have been able to find, negotiate and obtain the best components for our devices at the lowest prices.  Now, however, a major change is occurring which directly and greatly impacts the financial cost and time for development of all products, not just ours.

Since the 4th quarter of last year, we have seen indications that lead time and prices will be increasing dramatically.  At that time, and as we noted in a previous update, we started to source the major components which we believed would be in short supply and high demand.  We sourced enough components to fulfill all the existing preorders and a limited number of future orders.

For example, one component we use two of in Pocket P.C., an STM32F103 by STMicro, has increased from $2.30 to $8.30, a 400% increase in price. 

This striking increase in the cost of components, circuit boards and plastics leaves us no choice but to raise our prices on Pocket P.C. for future orders commencing on March 19, 2021.  As of that date, the new price for the purchase of a Pocket P.C. will be $299 and Pocket P.C. w/ LoRa will be $399. In addition, because of the new longer lead times, the newly-ordered units will not be available until the 4th quarter of this year.

For those of you who have already ordered, rest assured that you will be getting the product you ordered at the lower price.  

If anyone wishes to order any additional units at the lower price, you must do so before March 19th to take advantage of our special offer for our existing customers and supporters.

Jose Torres
CEO, Source Parts Inc.


Pocket P.C. is Alive!

Hello again and thanks for being a part of the Pocket P.C. community. We are excited to give you another update as we head into the final phase — the manufacture of the product you have been waiting for.

We had a production run in early February and a successful board bring-up for DVT2. We only had five PCBs assembled for this production run because had not worked with this factory before. We normally produce 25 units for a DVT.

Below are some photos from the assembly process:

Automatic Optical Inspection (AOI) of the PCBA after assembly.

Here you can see the LoRa antenna lettering being inspected. This is to ensure that the correct component has been placed. This is one of hundreds of points of analysis that the AOI machine does for each PCBA.

X-ray Inspection of the PCBA after AOI.

Here you can see again the LoRa antenna. The antenna is actually made of a special PCB and here you can see the traces on the various layers.

The factory owner personally helped us to test each device after all PCBAs went through AOI and X-ray analysis. After all boards were tested and powered on successfully, we carefully wrapped each board and headed home. When we finally left at around 10PM all the workers left for the holiday. We made it just in time!

The next day we shipped two units to Bootlin. They quickly got to work once they received the package. And the results are in!

First boot demonstrated in short-run of DVT2 PCBAs.

Taking Pocket P.C. out of the lab and into the wild.


We have started to post progress videos on YouTube which are being posted regularly. Make sure to subscribe to our channel to view our latest Pocket P.C. videos as they are released.

A video of flashing the keyboard / system controller with the built-in Black Magic Probe and a demonstration of a working keyboard will be uploaded next week.

Software Development

We will be working in the public and pushing changes to the following repositories for our U-boot, Linux and Buildroot changes respectively. Once the changes are thoroughly tested, we will be submitting patches upstream so that you don’t have to use our repositories.

Circuit Design

There is a lot of protection circuitry in Pocket P.C. — much more than most standard consumer electronics including most cellphones. We want Pocket P.C. to be a high quality and durable tool in your toolbox (or your pocket!)

As a result of studying this latest production run, we added five protection diodes in various parts of the PCB to prevent damage that can occur when using faulty chargers or cables. We also added a voltage regulator to the USB Serial port that can accept up to 30V. We always keep in mind that some defective USB-C chargers can output 20V by default without power negotiation which could cause some parts including the USB Serial converter to fail short, permanently ruining it. By adding the voltage regulator, the USB Serial port can handle these types of situations. We are doing everything possible to prevent cases of unintentional damage to Pocket P.C. to ensure that you will be able to continue using it for a long time.

During software development for the LoRa module and keyboard / system controller, we realized it would make things easier if we could use a UART to debug the firmware. The great thing about the built-in dedicated Black Magic Probe (BMP) device is that it offers us an additional UART. We have added an analog switch to share the UART on the BMP between the keyboard / system controller and the debug UART on the LoRa module. The LoRa module will now have both its UART1 and UART2 connected to a functional UART. It must be noted that the UART on the keyboard / system controller is shared with a ROW and COLUMN of the keyboard. If you are using the UART it will interfere with the operation of the keyboard. Just something to keep in mind.

We contracted a few engineers to do a full review of the design and outside of a few minor suggestions we gained their approval of the overall design. This gives us additional confidence that Pocket P.C. will be a reliable tool.

Next Steps

We will be doing another quick (10-15 day) production run to verify some of the changes we introduced into the latest version as a result of the lessons learned in the last production run.

After that, we will move straight into Production Validation Test (PVT) with Mass Production (M.P.) right after. The PVT should be less than 2 weeks to verify that our process to produce Pocket P.C. is sufficient to do so with high precision and without introducing defects.

Final Thoughts

Overall, at this point we are pleased with the design. This gives us confidence that Pocket P.C. will be a reliable tool you can depend on. We have about a month of development and additional testing before we can start PVT. This puts us into Q2 of 2021 as an anticipated ship date.

We will have a limited number of units available for evaluation for business use. If you have an urgent need to evaluate Pocket P.C. for your business, please reply to this email and we will try to accommodate you.

We appreciate your continued support and encouragement.

We promise to give you another detailed update as our exciting project continues toward completion.


Beating the Clock before Chinese New Year

We have been working nonstop this month and the last to get DVT2 into production and assembled before Chinese New Year. All factories take a holiday from February 5th to February 18th. Chinese New Year is on February 11th this year.

The process of verifying everything again was really worth it. We discovered an issue with the LCD pinout. Luckily, we had not yet ordered the PCBs and could change the pinout on the connector in less than half a day.

There were over a hundred changes and refinements made to the schematic, layout and BOM. Many were minor cosmetic changes to the schematic and some were major including moving and re-routing some components to accommodate the new antenna. We also swapped some data lines in the LPDDR3 Memory in DVT2 to make it function properly.

The latest schematic and layout has been open sourced and released on GitHub. You can click here to check out the latest files. We will release the design files after we start shipping Pocket P.C.

Getting a PCB Fabrication House to produce 10-Layer impedance controlled PCBs before Chinese New Year was a difficult challenge. We tried numerous PCB services and companies we know or have worked with in the past and none could start production until after the holiday. Many companies are trying to get existing orders out of the door and are not taking new orders.

Fortunately, one of our team members checked with one of his long term partner factory and they agreed to accommodate us.

As part of the normal process of auditing a new factory, we took a number of pictures. Here are a few.

PCB Copper Clad Laminate Storage Warehouse
Brown Oxide Machine
Manual Inspection Stations

There were a number of Engineering Questions (EQ) that were raised that required us to carefully check the potential issues before providing a response on how the fabrication house should proceed. This is part of the process of getting PCBs manufactured. Since our board uses some complex technologies such as a few Wafer Level Chip Scale Packages (WLCSP) that have very fine ball spacing, we had to get the manufacturing tolerance correct to avoid issues during assembly. One issue we had is that their processes can’t accommodate white soldermask for the WLCSP component footprints. Their solution is to use a green soldermask around these components while the rest of the PCB will be white. This will not be the case for Mass Production as the fabrication house we use for M.P. has more advanced machinery capability of higher tolerance.The color white was chosen for the PCB so that it can reflect the keyboard backlight LEDs thereby making them appear brighter. If we had chosen a different soldermask color, the true color of the LEDs would not come through.

Our perseverance is paying off. We are getting a quick-turn around on the PCBs and will be doing assembly of five pieces this week.We will be sending another update shortly after we have had some time to test the PCBs and let you know the results.


Perfecting Pocket P.C.

After a period of intense effort, we are back with an update with the latest developments with Pocket P.C. From onboarding a new factory to sourcing components, manufacturing a D.V.T. followed by board bring-up and formal verification all took much longer than originally anticipated. Now that those are all completed, we have a lot to share with you.

Our first production run with our new factory went extremely well. We manufactured 25pcs for a D.V.T. or Design Verification Test. We are extremely impressed with their production facility, processes, competence and skill that they demonstrated in getting the PCBs assembled. We were pleasantly surprised how thoroughly the factory performed during every step of the process.

After assembly, we did a formal verification which took a few weeks. We carefully examined every aspect of the project down to every single component.

As a result of exhaustive testing, we determined that we will have to do a second D.V.T. This will add a few weeks to our shipping timeline but we feel it is worth it to resolve a few critical issues that we encountered. We want to resolve these issues and test that the solutions are sufficient before starting a P.V.T.

  1. We accidentally swapped a few data lines in the PCB. This meant the RAM, SD, and one of the USBs did not operate as expected.
  2. A newly added power protection component interferes with the enclosure preventing it from closing properly.
  3. The LoRa antenna selected was not optimal for the location on the PCB. We had a meeting with the antenna manufacturer and they recommended a bigger antenna with a different layout requirement. The advantage of this antenna is that it is the same part for both low and high frequency bands. This antenna should also allow for better range than the previously selected component.

Following our formal verification, this week we had a productive meeting with representatives from all the factories involved in the manufacturing Pocket P.C.’s components. We wanted to ensure that everyone is on the same page. Each factory made their recommendations on how to improve the product and manufacturing process.


As you can see above, the keyboard is almost there.

Here are a few things we noticed and will be correcting in the next version:

  • The status LED is a little too bright which causes the blue to bleed into the main keyboard when it’s on. This is solved easily by increasing the resistance of the LED resistor to make the LED not as bright.
  • A backlight cover film is missing over the LED where the newly added “+ and -” buttons are which is why the keyboard is slightly brighter there. We will correct this in the M.P. keyboard cover film.
  • The keyboard was silkscreen by hand which means it is not as sharp as the M.P. version and the black is too thin. We will ask them to do two passes of black in the M.P.
  • There was a software file glitch at the factory which caused the rightmost button on the bottom to show question marks instead of the actual characters. We will ask them to correct and carefully review the silkscreen stencil against the proof before doing the silkscreen in the future.
  • Some characters are hard to read so we will be making them bigger in the final version.

Something which we believe we haven’t mentioned and would like to make you aware of is that the back cover screws into the front cover with 10 screws. This means that Pocket P.C. can be easily taken apart without great risk of damaging it during disassembly.

The assembly factory made a suggestion that we use hexagonal or triangle screws but we informed them we did not want to make it difficult for users to open by requiring a special screwdriver. We will most likely end up using phillips screws if there are no assembly issues during mass production that would require otherwise.


Besides the main issue of swapping data lines, we carefully reviewed the schematic and layout in its entirety and made a list of changes for D.V.T. 2.

If you are interested in what changes we will be making in the next revision, you can follow along with our changelog here:

Pocket P.C. Rev 2.1 Changelog

Further, we are commissioning an outside engineering firm to double-check everything. They will review the schematic and layout to make sure we don’t miss anything and they will give us an outside opinion on the overall design.


We decided to scrap our initial Arduino-based firmware for the Keyboard/System controller in favor of QMK (Quantum Mechanical Keyboard) Firmware. You learn more about this firmware here:

According to their website, “[t]he goal of the QMK software project is to develop a completely customizable, powerful, and enjoyable firmware experience for any project – keyboard or otherwise – and to provide helpful, encouraging, and kind support and feedback for people with any software development experience.”

Most of QMK itself is under GPL v2, but it includes software that are under various other licenses. We intend on upstreaming our changes to the original repository when they are ready.

As for the main software running on Pocket P.C., we will be working with Bootlin, an embedded development firm, to upstream everything from U-boot specific changes including Device Tree, Linux Kernel changes including Device Tree, Buildroot configuration and an Armbian build configuration.

This means that not only will we be supporting Armbian in addition to Debian but this should make it much easier for other distributions to be supported once the changes are accepted upstream.

Final Thoughts

If anyone has emailed us in the past few weeks, we will respond to all your questions soon. We apologize for falling behind in responding to customer inquiries but please know that we have been extremely focused on doing what needs to be done to get an excellent product shipped to you soon as possible.

We’ve taken a lot of pictures and videos which we have to edit together and are planning on sharing those soon.

Thanks for being a part of this great project.


Strengthening Pocket P.C. & An Unexpected Delay

We know you are eagerly awaiting your Pocket P.C. and we are working furiously with all of our suppliers and manufacturers here in China to complete production as soon as possible.

As you can imagine, the pandemic has had worldwide effects.  For example, it recently took two weeks for a wire transfer to be completed from the U.S. to one of our manufacturers in China.

Still, we keep overcoming hurdles and are moving along well with the process of completing the product with the highest degree of quality.  

Great interest has been expressed for Pocket P.C. from many individuals and companies, such as those in the maritime and scientific communities.

In keeping with our policy of letting you know our progress every step of the way, the following is a summary of recent developments in our drive toward completion.

Also, our limited-time lower price is expiring soon.  See details below if you wish to lock-in any additional units at the lower price.


Starting production soon!

Thank you everyone for being so patient while waiting for us to ship Pocket P.C. We want to ship a well-tested well-built product to you. This means that we have iterated through multiple prototypes and revisions before deciding to enter mass production.


Pocket P.C. Open Sourced!

If you would like to follow along with the latest design or would like to dive deep into the internals of Pocket P.C. we have created a repository on GitHub for the latest hardware files. The work is licensed under a Creative Commons Attribution-ShareAlike 3.0 United States License.