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MSP430FR5994 based wrist watch

Multi-function full color wrist watch using the MSP430FR5994 microcontroller.

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This watch is a barebones implementation of the MSP430FR5994 with a full color display, six input buttons, breakouts for I2C, SPI and UART. It uses a LiPo battery that lasts about 12+ days. It also has a port for an ESP82666 breakout.

This project was designed for me to personally learn more about electronics design and embedded software design. As such, there are guaranteed to be bugs, issues and things that can be improved. I recommend not taking any of my instructions or designs at face value. However, I do have a working device so I must of done something right(ish).

The watch itself is meant to be a fun project for a more advanced tinkerer/hacker/maker. The goal is to have something that is rugged and visually pretty enough for daily wear while offering several benefits to the electronics enthusiast. Specific design goals are:

Mechanical

  • Rugged and water-resistant for daily wear -- Failed
  • Visually not ugly for daily wear -- Failed
  • Reprogrammable without disassembling case -- Success

Electrical

  • Relatively inexpensive -- Failed (BOM is $50+)
  • Low Power, several days between charges -- Success (Lasts approximately 12 days in always on watch mode) 
  • Adjustable backlight -- Success
  • Utilize a novel binary entry method utilizing 6 buttons vice a touch screen interface -- Not yet started
  • Provide audible alarm -- Failed (Didn't even think about putting a speaker into it until already built)
  • Interface with ESP8266 for wireless capability -- Failed (Some unknown hardware bug causes device to reset when attached)
  • Able to accept daughter boards for device capability expansion:
    • Keyboard for text entry -- Not yet started (probably not worth doing)
    • Bluetooth -- umm, don't even know where to start
    • Temperature sensing -- Not yet started
    • Micro SD card for storage and data transfer -- Not yet started

Firmware

  • Tells time -- Success
  • Is able to decode and send I2C, SPI and UART data -- In progress
  • Able to display and edit text -- Display only (editing in progress)
  • Stopwatch, Timer, Alarm Functionality -- In progress
  • Able to capture and display analog signals -- Not yet started (practical limit of 3.3V)
  • Calculator Functionality

Known Issues:

  • Shorting ESP8266 VCC to ground causes really bad things
  • On device reset unused random pixels at top of screen
  • Setting device time does not function correctly due to BCD/decimal error
  • Device display does not clear properly following setting time
  • When turning off display, backlight may become fully turned on, requiring turning on then off display to clear
  • Year is not read properly (Century is hardcoded, note to self: Fix this some time in the next ~80 years) 
  • Day of week is not displayed properly

Lessons Learned:

  1. Finish your design specs before you build hardware. It is a lot harder to add a hardware function (like a speaker) after you have ordered the PCBs.
  2. Stop inventing the wheel. For every common thing that a processor can do, it's been done. While trying to write a function to draw lines on the screen, I floundered for about an hour to even comprehend how such a think is possible before discovering the Bresenham's Line Algorithm. Rosetta Code is amazingly awesome for this.
  3. Understand everything in the vendor code, but don't rely on it. I originally used vendor code to test and get the LCD working, but found that it left me without actually understanding what my hardware was doing. This being said, if you are not planning on writing a driver from scratch this isn't strictly necessary.
  4. Explode the prototype. I used an off the shelf SMD breakout board to prototype my specific processor on my specific LCD prior to assembling the whole mess. I really wish I spent more time exploring the firmware before I fully constructed the hardware. Then I would have known if my LCD was going to explode by changing the aforementioned code before combining it in a small combustible enclosure with other electronics.
  5. Document during design. Cool story, I actually designed and built the entire watch in February. Over the course of the year, I got busy and stopped at the point of getting numbers on the screen that may have been the correct time. It was late November before I got back to the project. I looked over...
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  • It Lives!

    Samuel Comeau01/01/2019 at 18:36 0 comments

    Back up and running. ESD was the issue. It seems that the programmer suffered an ESD event when I was handling it. The watch itself it thankfully no worse for wear. That was annoying. Still I have things to improve on the ESD safety of my work area. Also, Digikey is awesome. They got me a board in just a few days over a holiday weekend. Just outstanding service. On to hacking at the firmware until the crumbled pieces of code vaguely resemble their intent.

  • ESD is REAL!

    Samuel Comeau12/28/2018 at 22:41 0 comments

    So last night I was working on my watch. I had spent most of the day connecting pins on the external of the device to other pins to test for some sort of catastrophic failure. Then I tried to connect it to the MSP430FR5994 launchpad board to program it. It failed. I spent a while trying different combinations of computer restarts, different software and checking the wiring. I noticed whenever the watch was connected that it reset and stayed in a reset mode. This inferred two things. First, the reset pin on the watch is fully functioning. Second, the launchpad ezFET programmer was broken. Signs appear to be consistent with an ESD causing the reset pin to be shorted to ground. There are no other components between the ezFET IC and the watch IC besides a pull-up resistor. I then tried programming the target board on the Launchpad and nothing. I ordered a new one, but it will be about 2 weeks before it gets here. That gives me plenty of time to clean up my work area and get an actual ESD setup. 

  • First!

    Samuel Comeau12/28/2018 at 02:45 0 comments

    Today, I finally started to do the write-up for a project I have been working on sporadically for a bit. It is a wrist watch based on the Texas Instruments Low-power microcontroller the MSP430FR5994. These things are pretty great. They have a ton of power in a little package. They also take less current than a single LED while running at full-tilt. 

    I will continue adding things to this page, so subscribe or whatever. I mean the project is fully built, but I'm still working on the firmware.

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