lightmeter

A Lightmeter/Flashmeter for photographers, based on Arduino. TODO update this!

Task list

• Rewrite the code to use u8g2 instead of the Adafruit lib
• Investigate: why does it take 2 measures in ambient mode to get the actual result? (can the high res mode be used all the time?)
• Refactor the code - so it is easier to do the next step
• Modify the code, to work with 128x32 displays
• [ ] Find a solution to get rid of the arduino nano, and be more power efficient, and use rechargeable batteries (1.2V) ( + boost regulator) (see note 1.)
• Make the whole thing take up less space and RAM (currently ~26600bytes and ~1760bytes)
• Use the single/double buffer mode (with double buffer mode ~1000bytes - see note 2.)
• Use bitmaps insted of text where applicable (this helps to use smaller font set)
• Use custom fonts, and restrict them to the minimum number of characters needed (possibly numbers only)
• update the readme with the updated description, components and feature list. Also add credits to the original author!
• modify getBandgap() for the new board and schematic
• modify the schematic to have the buttons take up less pins
• New feature: kitchen timer functionality: add a buzzer, and add code to count down the measured time for bulb mode photography
• Indicate when the device is measuring - display a "measuring..." or similar text
• Draw new schematic diagram

Notes

1. I was aiming to use an attiny45/85 (or something along these lines), but even the u8x8 lib uses ~430bytes of RAM, and that is a bit too much for a device that has 512bytes. I could have used my own SH1106Lib (that is the display I am using) as it uses much less mem, but then we would have lost the ability to use any display you wanted. So I'm now using an Arduino Pro Mini clone.
2. Currently using double buffer mode. Speed is pretty good, RAM used is less than 1k. There is no need to use full buffer mode.

Components:

TODO update this list:

1. Arduino NANO v.3 https://www.banggood.com/custlink/K3Kvbdnnea
2. BH1750 light sensor https://www.banggood.com/custlink/mKDv2Ip1dr or https://www.banggood.com/custlink/GvGvnRNN0e
3. SSD1306 128*64 OLED SPI Display https://www.banggood.com/custlink/DDKmsdAQ6z
4. Buttons https://www.banggood.com/custlink/m3DGAYsnnY
5. 50x70 PCB https://www.banggood.com/custlink/KvvvnybQAP
6. AAA battery Holder https://www.banggood.com/custlink/vK3KsynANN

Thanks @morozgrafix https://github.com/morozgrafix for creating schematic diagram for this device.

The lightmeter based on Arduino as a main controller and BH1750 as a metering cell. Information is displayed on SSD1306 OLED display. The device is powered by 2 AAA batteries.

Functions list:

TODO update this list:

• Ambient light metering
• Flash light metering
• ND filter correction
• Aperture priority
• Shutter speed priority
• ISO range 8 - 4 000 000
• Aperture range 1.0 - 3251
• Shutter speed range 1/10000 - 133 sec
• ND Filter range ND2 - ND8192
• Displaying amount of light in Lux.
• Displaying exposure value, EV
• Recalculating exposure pair while one of the parameter changing
• Battery information
• Power 2xAAA LR03 batteries

Detailed information on my site: https://www.pominchuk.com/lightmeter/