HardLabs

Lightmeter

empdo·lightmeter

Lightmeter PCB layout, top view — open source AVR/Arduino board by empdo

About the Lightmeter PCB

Lightmeter is an open source AVR/Arduino PCB design by empdo, published on GitHub. It is a 2-layer board measuring 34.5 × 34.5 mm, with 32 components from 15 distinct parts.

Its main chip is the ATtiny1616-S, from the AVR/Arduino family. Other key parts include the VEML7700-TT. By type, the board carries 13 diodes, 7 resistors, 3 connectors, 3 switches, 3 capacitors and 2 ICs.

From the project

An open-hardware handheld photographic light meter. Set shutter speed and ISO on two dials, press the button, and one of nine LEDs lights up to show the aperture you should use. Runs from a single CR2032.

An open-hardware handheld photographic light meter. Set shutter speed and ISO on two dials, press the button, and one of nine LEDs lights up to show the aperture you should use. Runs from a single CR2032.

Three PCBs, fabricated together from one KiCad 9 project:

An ATtiny1616 reads a Vishay VEML7700 over I²C and drives nine charlieplexed green LEDs behind Bivar press-fit light pipes. Two Same Sky RDS-74365-45A rotary DIP switches set shutter speed (1–2000) and ISO (25–6400), read through a diode matrix.

Main components on the Lightmeter

ATtiny1616-SVEML7700-TT

Lightmeter bill of materials (BOM)

32 components, 15 distinct parts.

QtyPartRefs
1
ATtiny1616-S
U1
1
VEML7700-TT
U2
2
0022232041
Molex
J1, J3
1
640456-3
TE Connectivity AMP Connectors
J4
1
BLP2032SM-GTR
BT1
1
RDS-10S-74365-45A-D
S1
1
TS32-7-35-BK-B-160-RA-SMT-TR
S3
1
RDS-16S-74365-45A-D
S4
4
BAT54A
D1, D2, D3, D4
9
Green
D12, D13, D14, D15, D16, D17, D18, D19 +1
1
10uF
C1
2
100nF
C2, C3
4
100R
R1, R2, R3, R4
2
4.7k
R5, R6
1
10R
R7

Lightmeter design files

The KiCad project lives in the empdo/lightmeter repository on GitHub; these links point at the commit this page was built from.

Lightmeter: common questions

What microcontroller does the Lightmeter use?

The Lightmeter is built around the ATtiny1616-S, from the AVR/Arduino family.

How big is the Lightmeter PCB?

The Lightmeter measures 34.5 × 34.5 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Lightmeter?

32 components, from 15 distinct parts. The full bill of materials is listed on this page.

Where can I download the Lightmeter design files?

From the empdo/lightmeter repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the Lightmeter design in my own project?

The repository has no license, so all rights stay with empdo. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the Lightmeter without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug AVR/Arduino firmware against it before you order a PCB.

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