Yet another good news from us. We have now manufactured new boards and they all work as expected. We are tuning our procedure together with Hanza to avoid problems in the manufacturing process in the future.
These boards are now used to verify the software we have developed. We started by integrating the different software blocks that we had developed. So far we have been able to pair ReVault with a mobile phone and tablet and transfer files from a mobile phone to ReVault and vice versa, look at pictures and listen to music over the web server, receive notifications and set up timer and edit settings. We will continue integrating more software blocks and working on software stability.
We are getting there.
Wish you all Happy Easter holidays
This is another update on the development of ReVault from our hardware Engineer Martin Layley.
Touch wood, the verification of the hardware is now done by 99%. Arun has nearly completed the hardware verification and the low level software drivers. We now have verified the following as working:
- Power supply system
- LCD and backlight
- MPU internal flash
- MPU internal SRAM
- Pulse oximeter
- The WiFi part of the radio
This just leaves the Bluetooth section of the radio, which is being worked on as I write. The Bluetooth is in operation on the evaluation boards, so it should not require much more than re-mapping a UART and some interrupts.
We have video of a debug session with the WiFi doing a scan of the local environment.
In the process of getting the WiFi working, we discovered that I had drawn the PCB footprint for the radio chip inverted. Hanza desoldered it and I have put it back on dead-bug fashion. Dead bug? lying on its back, waving its legs in the air.
The radio is quite small, he pads are 0.4mm diameter, and the wire is nominally 0.2mm diameter, so soldering is a challenge and must be done whilst looking through a microscope.
As the wires are fragile, the prototype has been boxed and is now being used for the software integration.
With the basic design proven, we are constructing two more units for the software team to use.
So we are getting closer with fast steps, expect more good news from us in the near future.
The screen is now working with the software. It’s a 262K RGB color display with a 320×320 resolution.
Magnus, our software architect, describes his work with the screen and graphical interface.
Magnus also goes on to discuss the printed circuit board.
I hope that you are all doing well.
I am happy to tell you that we have made several important steps in our development. As we previously shared we have manufactured the first electronics and we are now verifying several parts of our software on it. We have recently finalized the development of:
+ The security we promised you.
+ The display, we can now show display graphics on it
+ The wireless charging
Other parts of ReVault are under development and they are coming along nicely. We will continue to work hard and keep you updated.
Finally I would like to thank you for your support and patience.
I hope you have a great weekend!
Last week Hanza, our assemblers, sent two boards down their production line. The first went with just solder paste, no components, to check the quality of the solder mask. They were sufficiently happy with it, to program the pick and place machine to assemble a second.
There are components on both sides of the PCB. Here, the back side has been assembled.
As the PCB is thin and contains flexible sections, it must go down the line on a carrier. There is one for each side and they have been made by milling FR4 laminate. Here is the second carrier.
And here is the PCB on it, ready to go down the line for the second side assembly.
The first stage is screen printing solder paste.
Then comes the component placement.
The final stage is to go through an oven, where the board reaches a temperature of 240C and the solder melts.
We x-ray inspected the board.
The display is monochrome. Here, I have highlighted some potential issues.
In my last post, I mentioned that the holes in the PCB had not been filled. Circled in cyan are solder joints which have voids in them. These voids are caused by trapped air expanding when the boards are heated. The good news is that none of these appear to be bad. There are no solder bridges, so no short circuits, and the voids are probably not big enough for open circuits.
In red, I have circled 3 joints where there is a through hole in close proximity. Here, a substantial amount of solder has flowed down the hole and is not available for joining the component ball to the PCB. This was expected. The good news is that there is some solder and that there might still be enough for the joints to work. If this is so, then we are still on schedule.
We can also report that we’ve tried the charging with these PCB and it worked flawlessly.
This post will focus on our development on the hardware front. Josef, our CEO, will be sharing about other aspects of the project next week.
The first batch of PCBs have arrived.
On inspection through a microscope, they look like the surface of the moon, whereas they should be almost perfectly flat. We are trying to solder devices with incredibly small sizes: in the photograph with the gold craters, each of the circles is a pad that we are going to try to solder to. These circles are 0.285mm across and the gaps between them are only 0.115mm. The craters are roughly 0.1mm across and about the same deep and they make a connection to some other metal tracks inside the PCB.
In the picture below, which is from a board that I designed a year ago, it is just possible to see a dot in the middle of some of the gold pads. This board is the same thickness and has the same number of layers, but the holes have been filled in before the final coating of gold has been added. This is what should have been done with our boards.
All is not lost though. We have been able to use one board to prove the mechanical design. We have wrapped one of the PCBs around the plastic frame that we printed last month and attached an LCD. From this, we have confirmation that the LCD connector is in the correct place.
The solder paste screens are currently being manufactured. They are due in this week. Once we have them, we can use some of the boards to tune the production line. From this, we shall get one board with the antenna and a test connector. This will then go to a local facility so that the correct antenna matching components can be found. As with CB radios, correctly matching or tuning an antenna improves its performance. We need two different tunings, as some boards will be placed in watch cases and others will be used by the software developers without a case.
When the boards arrived, I measured the coil for the wireless charging. This is the octagonal spiral you can see on one of the photos. The QI charging works at 100kHz. The coil acts as an antenna and also needs to be tuned. Because there will be a battery inside the box, we have to add shielding to the PCB so that the battery is not heated by the RF. Hot lithium batteries are generally considered to be best avoided and even though our battery contains only a minuscule amount of Lithium, the shielding is required. Adding the shielding detunes the coil, so this has to be measured and then compensated for. The benefit is that properly tuned, it improves the performance of the wireless charging. The shielding is the silvery pad with the hole in the middle.
The second batch of PCBs are due the first week of February. We should have everything ready for them.
As parts of the world shut down for Christmas, our prototype manufacture progresses. PCBs should reach us in the first half of January. They will be assembled here in Sweden by our colleagues at Hanza.
Now that the electronics package is fixed, we are modifying the 3D model of the watch body, to make it fit. As the body is made from stainless steel, it affects the performance of the WiFi and Bluetooth antenna. We are aiming to have physical prototypes of the body back in time for the PCB assembly, so that we can do the antenna tuning.
We would like to wish all our backers and community a fantastic holiday! We look forward to bringing ReVault to you in 2016.
This is a note from Martin Layley one of our hardware engineers:
Earlier this year, we produced a development board containing the MPU, storage and the WIFI + Bluetooth circuitry. This highlighted a few problems with the support from the manufacturers and prompted a redesign of the electronics. After evaluating many alternatives, we decided to keep the same WIFI + Bluetooth circuit, but change the MPU from Atmel to STM.
We have a single flex-rigid board which will fold around the battery and then drop into the watch casing. This new board is the most difficult one I have ever laid out. My original aim was to use 6 layers with 125um features, as we did with our development board. To keep the board thickness down, this had to be shrunk to 4 layers and the feature size dropped to 100um. Whilst I have drawn boards with 75/85um features before, fine lines are not currently compatible with flexible boards. Board thickness is important, as we fold it around 3 times. Consequently, every 100um decrease in the PCB thickness slims the watch by 0.3mm. To enable the board to fold, it is milled to make it thinner. This does not show on the 3D plots.
The first batch of boards will have the connector panel. This will snap off to enable the rest of the board to fold up into the watch case. Production boards will have a test coupon instead, which will work with a production test jig.
Why a new MPU?
Changing processor family was though but it will offer additional useful benefits such as: Access up to 8MB RM, instead of 1MB. A much faster eMMC interface (1600Mb/s instead of 192Mb/s). The CPU can run faster if we need it and there is a hardware block to assist with some of the encryption/decryption functions. The DMA engine is also more flexible. We get more pins which allows more sensors.
The downsides are that the active current goes up, as the MIPS/MHz figure is higher and that DMA transfers are limited to one active at a time, whereas under some conditions, the Atmel MPU could manage two DMA transfers simultaneously with CPU activity. How this affects the battery life remains to be seen, as predictions require a fairly accurate idea of CPU activity, I/O block activity and sleep durations but we don´t think it will affect that much.
What you get from this, is that we have upgraded the accelerometer to include a 3-axis gyro and a 3-axis magnetometer. We have also included a pulse oxiometer, which is capable of reading both pulse rate and blood oxygen levels. This article in EDN is a good introduction to the subject: http://www.edn.com/design/medical/4425641/Pulse-oximetry-basics-and-MCUs
We have been working around the clock to finalize ReVault and deliver it on time. We have some bad and good news.
The bad news is that we have delays in our production and will not be able to deliver your order until the end of June. The reason being that we have been forced to redesign our electronics from scratch, due to a lack of support from the manufacturers of the Wi-Fi and Bluetooth chip. This has been a major headache for us, but we did not allow it to break us. Contrary, we have solved these problems and also paved the way for the following positive news.
The good news is that we have leveraged this redesign to include a heart rate monitor, gyro and compass. With these new components we will be able to add new functions in the future, such as activity tracking and heart rate monitoring. As a Revault backer, you will not pay any additional fees for these new components and functions. Developers will also have access to this new sensor data through our API.
Please read our latest blog post, from our hardware engineer Martin, if you want to learn more about the redesign:
We are currently preparing the production of the first batch of electronics. We look forward to keeping you updated, and delivering Revault to you.
ReVault has during the summer evolved from a mix of ideas and requirements to reality. We have specified the user needs, and the user stories. We have discussed user personas, business impact maps and the input from the community surveys and put together and prioritized the information pieces.
One interesting question has been: what info and functionality should be in the mobile and/or ReVault app? Following the information structure we have created two interaction designs in the shape of wireframes for ReVault and for the mobile apps. The next step is to evolve the visual design (as seen in the ReVault video). This is done in parallell with the coding.
Micke, a proud member of the ReVault team
My passion and profession for the last twenty years is usability and interaction design. From CD-rom edutainment in 1995 to B2B Webs in IBM, interactive television in Motorola/Google, responsive Web design and best selling iOS apps, etc. And now – finally – technology has come to wearables, the step before including IT in our bodies!
Do you have any questions or suggestions? Make a comment, or request access to the Google document..