In the last 3 Years I have built a few different smartwatches for myself.
Im not a typical smartwatch user but really interestet into the technology involved to build them.
Most of the watches that I've build had a small 8-bit Atmel, a HC06 for the Bluetooth communication and a oled dotmatrix display. As smartwatches became more popular google released a watch version of their android called android wear and I thought about building a new watch. But this time a really powerfull one with a ARM processor running android wear or a custom os.
Most of the watches that I've build had a small 8-bit Atmel, a HC06 for the Bluetooth communication and a oled dotmatrix display. As smartwatches became more popular google released a watch version of their android called android wear and I thought about building a new watch. But this time a really powerfull one with a ARM processor running android wear or a custom os.
And because this wasn't crazy enough I decided to use a round display with capacitive touch. After some research I found a round 1.5" lcd with free viewing angle. The interface on this lcd is called MIPI-DSI. This interface type is used in almost all newer smartphones and wearable devices, because it uses only a differential serial signal to transmit the LVDS signals to the display. Also this display features a serial capacitive touch interface. I ordered the display and a few days later it arrived in my mailbox. Now it was time to search for a matching processor. I found some ready-made platforms by a Chinese manufacturer and considered using them. At the time I found their website (about 1 1/2 Years ago) they haven't offered a complete solution as there doing at the moment I'm writing this blog. But the M200 SOC had almost everything I need. A Mipi interface, serial touch, small form factor, low power consumption and it is capable running android.
Unfortunately the project suspended until now, because I was too busy and a project like that really needs a lot of time... The only thing that is stopping me at the moment from buying one of their development platforms is the bad documentation. I really don't want to spend a lot of money for a board that I'm not capable using. Another point is that I would need to build a adapter pcb for at least the display and touch interface. Also software wise I don't really know if I'm capable enough writing my own lcd driver for this SOC... Because of these arguments I searched further for some alternatives . Fortunately ST Microelectronics released a few new Cortex M4 processors (STM32F469 for example) including a MIPI interface. They also feature a graphics accelerator Chrom ART to enable smartphone like graphics. I love the way ST does their documentation so using their processor should be doable. Unfortunately using this processor would cause me to write my own watch os, because android would not run on this processor (as far as I know). At the moment I don't know which way to go. Let me know your opinion to this in the comment section!
