Welcome back to another Popcorn Computer update!
We know a lot of you have been patiently waiting for an update. We have been extremely busy working on the final development and production of the units and in navigating our way through the constantly-changing Shenzhen electronics environment.
First, we would like to clarify any confusion that may have arisen from our previous email. The units we started shipping at the beginning of October are going to software developers who are working on porting new operating systems to Pocket P.C. and working on the firmware.
Here’s what we learned from our last production run.
The footprint for the chokes used on the high-speed DSI signals lines had a fault in the pinout. DSI stands for Display Serial Interface which is where all the LCD data is transferred over from the SoC to the Display Controller IC.
This meant, we could not receive an FCC ID and certification using the PCBAs from this production run. The PCB used for certification has to be “electrically equivalent” and since we are making some changes to the routing, this could affect emissions in unexpected ways.
This has been corrected in the design.
FCC EMI Testing
In the meantime, we have been contacting multiple testing houses to inquire about quick turnaround times. Thanks again to our antenna vendor, Unictron, who suggested a few testing houses which could accommodate our needs. Once again, it comes down to who you know and being on the ground in Shenzhen and making face to face contact (with masks on!).
We are in the process of doing a preliminary EMI test to make sure that there are no major issues with the PCB that would force us to have to correct and to do another production run. This update is being sent later than anticipated because we had to create the necessary software and written materials to allow for this testing.
We will have the results within the next two weeks.
In the last production run, we moved the GPS module from the top of the PCB to the bottom. This was done to provide greater clearance for the LoRa antenna. Because of this, we need to modify the mold. Luckily, the mold change is straightforward and should be completed within 2-3 weeks. Once completed and verified, we can start mass production of the plastic enclosures.
Since we conceived of an improved derivative of C.H.I.P, which we called Original Popcorn in 2018, we have gone through four revisions. The last two were planned to be the production units since we believed that we had corrected all the issues found in the earlier versions.
USB Type-C Power delivery is really complicated. This is doubly so when you don’t select the right Power Delivery IC. We initially chose a Cypress component which turned out to be a PSoC4 internally instead of a custom ASIC. This meant it required a number of external support components. Further, Cypress would not provide any SDK or firmware source for us to modify and instead insisted on providing a firmware blob. We then chose an IC from a Chinese vendor which used a tool written in Visual Basic 6 to program the flash in the IC. Again, we were not allowed to view the source code and any development would take months to implement. Finally, we looked at and chose a Texas Instruments TPS65988 Power Delivery IC which has good support software that allows us to customize the settings of the device. A customized version of this IC is used in the latest Apple Macbooks.
All of this work on the Original Popcorn was not in vain. The power circuit we used on Original Popcorn is the same circuit we used on Pocket P.C. Along the way we learned which are the best manufacturers to use, where to purchase quality parts at low prices and we developed a process for verifying a design before ordering the PCBs.
For those who have preordered an Original Popcorn, some of whom have waited a very long time, we are offering a free pre-production unit. We have already begun shipping them out this month to those who said they would like one and will continue shipping them out within the next few weeks.
There are three errata with the pre-production units.
- We originally intended to use the GPIO on the TPS65988 Power Delivery IC for the 8 “XIO” GPIO pins on the pin header. We wanted to get rid of the IO Port Extender used on C.H.I.P. as it could not source power as well as it could sink. Unfortunately, when it came time to write the Linux driver for the GPIO we learned of significant limitations to the ability of the GPIOs in how it handles inputs. To resolve this issue, we added a more advanced port extender which is controlled over I2C which also doubles as an 8-bit ADC meaning all 8 “XIO” pins can read analog voltages. This is a feature that C.H.I.P. lacked.
- The other issue with the pre-production units is that we missed routing a trace for the enable pin on the power switch for the USB ports. (A hyphen instead of an underscore mixup caused the net to be left unconnected.) This power switch allows Original Popcorn to supply power to the USB ports when powered off the battery or through the CHG-IN pin on the pin header. We corrected this.
- The third issue is that we connected an active-low reset signal for the TPS65988 PD IC to a pin on the R8 CPU that is pulled-up on boot. This meant that if Original Popcorn is powered over the USB then it will infinitely reset. We solved this problem by putting a 0R pull-down resistor on this signal in the pre-production units. We have since moved this reset signal to another pin on the R8 CPU without the pull-up.
We are gearing up for production of the final version of Original Popcorn this month. We are planning to share video on our Youtube channel of the manufacturing and testing process. We will send another update when that video is ready.
With working units shipped to developers and all remaining issues identified, all that remains to be done is the corrections to those issues and obtaining certifications which are already in motion.
As more developers receive their units this month, we will share their developments with you. We plan on showing you different graphical environments running on Pocket P.C. in a separate video on our Youtube channel soon.
We are keeping a close eye on shipping logistics and the supply chain. We have had a shipment of developer units delayed because DHL postponed all package pickups due to the high-volume of packages in their warehouses. We are in discussions with multiple third-party logistics companies and will be making the decision soon on whether to ship packages individually from Shenzhen or Hong Kong or send bulk shipments to warehouses in Europe and the United States and ship from there.
Finally, while we try to send an update out each month the timing can vary depending on various information we are waiting to receive from manufacturers or suppliers. To ensure regular updates, we will adhere to sending an update on the first of every month. As we receive more information throughout the month, we will send a follow-up update. We hope this will allow you to have the latest information on a regular basis.
We can’t wait to get Pocket P.C. in your hands. Please be assured that we are working everyday to make that happen as soon as possible. If you have any questions or concerns, please feel free to reply to this email and we will try our best to get back to you as quickly as possible.