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sawasdee01 Newbie Joined: 23/12/2016 Location: United KingdomPosts: 33
Posted: 09:46am 16 Feb 2019
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Hello Everyone,
Please find a couple of photos of an early prototype wearable, which runs STM32L4 MMBasic, below:
Key features:
- STM32L433 running MMBasic - BL652 Bluetooth 5 / BLE - programmable in SmartBasic - Virtual Serial Port connection to the MMBasic comm port via Bluetooth BLE - Harwin Micro Connector for 1.54" 240x240 ST7789 based display - Connector supports I2C Capacitive Touch screen included with the display - On board FT230X UART to USB with full driver support in Win 10 and Android - On board USB LiPo charger for 300 mAh battery - On board 3.3v reg - Battery charge sense input to CPU - Basic battery level measurement via simple voltage divider into A TO D - SWD port for STM32L433 - Basic SWD port for Bluetooth module (main pins but w/o power) - BOOT0 Hi/Lo solder patch, allowing serial loading of MMBasic - As this is a prototype, there is a jumper patch allowing the USB to be configured as either; - connection to STM32L4 MMBasic console OR - connection to Bluetooth Module UART (eg for Smart Basic Development) OR - connection between Bluetooth Module UART and STM32L4 MMBasic for the purposes of communicating via the Bluetooth Virtual Serial Port.
Please note that serial connectivity is not well supported in Bluetooth BLE. At the moment, I have a very basic third party serial terminal emulator, running on Android, which is capable of talking to the STM32L4 MMBasic via Bluetooth BLE.
Unlike Bluetooth Classic, Bluetooth BLE seems to be designed for exchanging a few bytes at a time over much longer distances (ie mostly for IOT style projects). Although this doesn't rule out the possibility of serial comms, it does make things harder. If anyone has any thoughts on how to resolve this issue, I would be grateful to hear them. I know that Basic 4 Android has BLE libraries and this may help.
Next Steps:
The pictures show an initial prototype with everything working, with the exception of the display. I am awaiting the arrival of second prototype PCBs from China to resolve a PCB connection error. The second prototype will also replace the enormous jumper patch with mini jumpers and re-locate the Harwin 24 way connector to allow the display to better fit into the watch enclosure (shown in the photograph).
The main outstanding item would then be the creation of a touch screen driver for the capacitive touch screen. As this is outside my area of expertise, any help from Peter or another would be very gratefully received.
I am not entirely sure where this project will go, as I am very busy with several different ideas, at the moment. Any feedback is gratefully received and will help with the direction of travel.
Best wishes.
Sawasdee
matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10572
Posted: 10:01am 16 Feb 2019
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Very nice
You don't need a driver for basic touch screen operation. I assume there is an interrupt output from the touch controller. Just set this up to trigger a normal basic interrupt and then read the I2C from basic to get the data.
sawasdee01 Newbie Joined: 23/12/2016 Location: United KingdomPosts: 33
Posted: 02:53am 06 Mar 2019
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Hi,
Update on the STM32L4 MMBASIC wearable:- The 1.54" displays arrived from China, along with the revised PCB. Please see photos below:
It is worth noting;
- see first message in this topic to view the spec of the wearable.
- the display LED backlight is switchable from the CPU, so can be activated via the touchscreen, dimmed using PWM, etc.
- I have not fitted the Bluetooth 5 module in the watch shown in the photos. I will fit and test, shortly.
- the huge jumper pins fitted in the previous prototype (see photos in first message in this topic) have been replaced with micro jumper pins, allowing the unit to be fitted into the watch enclosure.
- there are still a number of (mainly, mechanical) issues to be resolved, so there will be another version of the PCB, when I find some time.
Best wishes to all.
Steve
Frank N. Furter Guru Joined: 28/05/2012 Location: GermanyPosts: 983
Posted: 09:24am 06 Mar 2019
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Hi Steve,
very impressive! I have been planning something similar for a long time! Are you planning to sell a kit?
Frank
sawasdee01 Newbie Joined: 23/12/2016 Location: United KingdomPosts: 33
Posted: 12:50am 07 Mar 2019
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Hi Frank,
If I manage to resolve the various mechanical issues and can make the procurement angle work (eg volumes for watch cases, displays, etc), then the kit might become available via a UK based outfit.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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