2 layers50.8 × 50.8 mm
DC2026 LASIR
CmdrZin/chips_avr_examples
AVR assembly and C code for robotics and other projects.
38 parts6MIT
2 layers81.2 × 46.1 mm
Lightmeter
empdo/lightmeterAn 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.
- Size
- 81.2 × 46.1 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 47
- Nets
- 38
- Pads
- 121
- Tracks, vias
- 175, 41
- Pours
- 4
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 5 Sep 2026
- Updated
- 9 Sep 2026
Overview
Lightmeter is an open-source printed circuit board by empdo, from the empdo/lightmeter repository on GitHub. It is a 2-layer board of 81.2 × 46.1 mm with 47 parts on 38 nets, routed with 175 tracks and 41 vias.
It is built around the ATTINY1616-SN, VEML7700-TT and BAT54A, with the BLP2032SM-GTR, RDS-10S-74365-45A-D and RDS-16S-74365-45A-D among its other parts. Its parts include 13 diodes, 7 resistors, 3 capacitors, 3 connectors and 3 switches. It belongs with the AVR (ATmega, ATtiny) boards of this library.
Main components
6
ATTINY1616-SN
SOIC-20-300mil-40℃~+105℃ 1.8V~5.5V 16KB 18 20MHz 256Byte 2KB 8 Bit AVR Built-in FLASH SOIC-20-300mil Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
VEML7700-TT
SMD-4P-25℃~+85℃ 120klx 16bit 2.35mm 2.5V~3.6V 3mm 6.8mm I2C Light Intensity Low power/sleep mode、Spectral correction/filtering、High dynamic range measurement、Adjustable gain control、Interrupt/event trigger、Built-in temperature compensation SMD-4P Ambient Light Sensors ROHSVishay IntertechnologyAmbient Light Sensors
BAT54A
SOT-231 Pair Common Anode 200mA 2uA@25V 30V 600mA 800mV@100mA SOT-23 Schottky Diodes ROHSNexperiaSchottky DiodesBLP2032SM-GTR
SMD-40℃~+260℃ SMD Button And Strip Battery Connector ROHSMPDButton And Strip Battery Connector
RDS-10S-74365-45A-D
插件插件 Rotary Encoders ROHSCUIRotary EncodersRDS-16S-74365-45A-D
插件插件 Rotary Encoders ROHSCUIRotary Encoders
README
README.mdLightmeter
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.
Status: Designed, not yet built
[PHOTO]
Hardware
Three PCBs, fabricated together from one KiCad 9 project:
| Board | Size | Purpose |
|---|---|---|
| Main | 34.5 × 34.5 mm | MCU, LED readout, dials, battery |
| Sensor | 34.5 × 5.4 mm | VEML7700, on a 4-wire cable |
| Faceplate | 34.5 × 34.5 mm | Dial scales and light pipe holes. No copper. |
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.
Parts. See production/bom.csv.
- LEDs need Vf ≤ 2.2 V — pure-green 520 nm parts won't light from a coin cell
Repository
hardware/ KiCad project and custom libraries
docs/ Schematic PDF, board renders
production/ Gerbers, drill files, BOM
mechanical/ Fusion archive, STEP, printable STLs
firmware/Parts
47| Qty | Value | Footprint | References |
|---|---|---|---|
| 9 | Green | PCM_SparkFun-LED:LED_0603_1608Metric_Green | D12, D13, D14, D15, D16, D17, D18, D19, D20 |
| 9 | ledhole | digikey-footprints:NPTH pad | H1, H5, H6, H8, H9, H11, H12, H13, H14 |
| 5 | MountingHole | MountingHole:MountingHole_2.2mm_M2 | H2, H3, H4, H7, H10 |
| 4 | 100R | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R1, R2, R3, R4 |
| 4 | BAT54A | Package_TO_SOT_SMD:SOT-23 | D1, D2, D3, D4 |
| 2 | 0022232041 | digikey-footprints:PinHeader_1x4_P2.54mm_SolderPad | J1, J3 |
| 2 | 100nF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C2, C3 |
| 2 | 4.7k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R5, R6 |
| 1 | 10R | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R7 |
| 1 | 10uF | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C1 |
| 1 | 640456-3 | digikey-footprints:PinHeader_1x3_P2.54_Drill1.1mm | J4 |
| 1 | ATtiny1616-S | Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm | U1 |
| 1 | BLP2032SM-GTR | BLP2032SM_GTR:BAT_BLP2032SM-GTR | BT1 |
| 1 | RDS-10S-74365-45A-D | RDS_10S_74365_45A_D:SW_RDS-10S-74365-45A-D | S1 |
| 1 | RDS-16S-74365-45A-D | RDS_16S_74365_45A_D:SW_RDS-16S-74365-45A-D | S4 |
| 1 | SolderJumper_2_Open | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP1 |
| 1 | TS32-7-35-BK-B-160-RA-SMT-TR | TS32_7_35_BK_B_160_RA_SMT_TR:SW_TS32-7-35-BK-B-160-RA-SMT-TR | S3 |
| 1 | VEML7700-TT | PCM_SparkFun-Sensor:VEML7700-TT | U2 |
Questions
How big is the Lightmeter PCB?
It measures 81.2 × 46.1 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Lightmeter use?
47 parts, built around the ATTINY1616-SN, VEML7700-TT, BAT54A and BLP2032SM-GTR. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Lightmeter KiCad files?
From the empdo/lightmeter repository on GitHub, at the commit this page was made from: the board is lightmeter.kicad_pcb and its schematic lightmeter.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Lightmeter design in my own project?
Its repository states no licence, so its author keeps all rights: ask empdo before reusing the design.
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