My friend Katja loves inspirational quotes. Loves them. All the time, on the facebook with the inspirational quotes.
This project is to make a 'magic mirror' - essentially, a small picture frame with one-way mirror glass, a microcontroller board, TFT display and SD memory card that will deliver an inspirational quote at the touch of a button.
| Components | Src | Cost | Notes |
|---|---|---|---|
| Maple Leaf Mini | 1 | £2.81 | STM32 32-bit ARM cortex-M3, 120KB/4KB |
| 240x320 SPI TFT LCD | 1 | £2.99 | ILI9341 display, SD card reader |
| Prototype board | ? | ? | 7cm x 9cm |
| Two buttons | 1 | ? | From a pack of components |
| 3 x AA battery holder | 2 | £3.51 | Has an on/off switch - 2 x AA would work |
| Picture/Photo Frame | 2 | £6.79 | MDF Picture/Photo Frame, 12.5cm Diameter |
| One-way mirror film | 2 | £5.99 | 50 x 100cm - still got loads left |
| SD Card (8Mb) | ? | ? | An old one I had lying around |
- Ebay.co.uk
- amazon.co.uk
Initial protoboard lash-up showing the startup screen.
The test button on the back will then display a quote.
Here you can see the mirror when in-active (screen off, deep sleep). Yes, that
handsome beast behind the camera is me. The reflection is quite dark but
servicable.
When the button on top is pressed, a quote is displayed for ~7-seconds.
Here you can see the gubbins on the back. The button on the board can also be
used to trigger a quote to be displayed and the button cunningly stuck/wedged
into the top of the picture frame is connected by header pins. The battery back
is held to the frame stand by an elastic band (no expense spared).
In deep sleep, the system consumes ~10 mA, which means it should last about a
week - not that great.
When active, it consumes ~30 to 50 mA. After the first deep sleep it appears
the clock runs very slow - which is okay with me for this project.
I used a bit of python to ensure the formatting of the quotes. I wrote one great big cut-and-paste quote file and then used the script to split this into correctly formatted individual quote files.
Each quote file has the name 'FILE####.txt'. The SD card Ardino library only supportw 8.3 filenames. The sketch only selects filenames that start 'FILE', everything else is ignored.
The quotes are served up in a psuedo random kind of way. When reading the next quote file in, the code will randomly skip 1 to 5 files so that after switching on the quotes seem a little randomised.
Pressing the Maple Mini User button within 3-seconds of the welcome message "Katja's Marvellous Magical Motivational Mirror" will put the system into test mode, in which it displays each message one after the other, and indicates the quote file name for each as well. Doesn't use deep sleep in test mode so this is useful for debugging and for re-programming.
After the Welcome message is displayed, the first button press displays an initial quote from the Tao of Programming, which is hard coded. After that, each button press reads a quote file and displays it.
The font library is very limited and trying to display a character not in the font will crash the sketch :( Had to be careful with the German quotes not to use any umlats!
I glued the button into the frame with Gorilla glue - which got into the button (despite it being wrapped in tape) and caused a short - that was annoying and difficult to diagnose.
Had to make the input button a pulldown input to work reliably - that is probably costing some current.
Also, the tft panel logic is on (although not the display led) - maybe that could be powered up each time.
Putting the Maple Mini in to deep sleep and then waking it up again makes it run really slow - which is not a problem - some kind of clock setting issue but it works for my application so I didn't try and fix it.