2 layers136.7 × 95.4 mm
Steering Wheel
Nomalah/Budget-Racing-Electronics
All electronics for the budget racing vehicle
32 parts
4 layers82.5 × 35 mm
Co2 7seg
morzack/CO2-PCB-MonitorDesign and manufacturing files for a desktop atmospheric CO2 monitor
- Size
- 82.5 × 35 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 45
- Nets
- 54
- Pads
- 207
- Tracks, vias
- 533, 61
- Pours
- 4
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 13 May 2025
- Updated
- 16 Dec 2025
Overview
Co2 7seg is an open-source printed circuit board by morzack, from the morzack/CO2-PCB-Monitor repository on GitHub. It is a 4-layer board of 82.5 × 35 mm with 45 parts on 54 nets, routed with 533 tracks and 61 vias.
It is built around the ATMEGA328P-AU, MIC5205-5.0YM5 and MIC5366-3.3YC5-TR, with the LDS-C814RI among its other parts. Its parts include 15 capacitors, 12 resistors, 5 ICs, 4 diodes and 3 transistors. It belongs with the sensors and measurement boards and the AVR (ATmega, ATtiny) boards of this library.
Main components
4
ATMEGA328P-AU
TQFP-32(7x7)-40℃~+85℃ 1.8V~5.5V 10bit 1KB 20MHz 23 2KB 32KB 8 Bit AVR Built-in FLASH TQFP-32(7x7) Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
MIC5205-5.0YM5
SOT-23-5-40℃~+125℃@(Tj) 1 150mA 180mV@(50mA) 20V 2uA 5V 70dB@(1kHz) Fixed Over Current Protection、Over Temperature Protection Positive SOT-23-5 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSTECH PUBLICVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
MIC5366-3.3YC5-TR
SC-70-5-40℃~+125℃@(Tj) 1 150mA 155mV@(150mA) 200uVrms 29uA 3.3V 5.5V Fixed Over Current Protection、Over Temperature Protection Positive SC-70-5 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSMicrochip TechnologyVoltage Regulators - Linear, Low Drop Out (LDO) RegulatorsLDS-C814RI
DIP-130.8 1 105mW 27.7mmx2mmx8.4mm 7 Segment Common Cathode Red DIP-13 LED Segment Displays ROHSLumexLED Segment Displays
README
README.mdCO2-PCB-Monitor
This repo contains the hardware and software required to manufacture and assemble a small seven segment CO2 monitor.
The monitor is built around a 4 digit seven segment display (with automatic dimming based on ambient light) that displays the current atmospheric CO2 concentration as measured by an Adafruit SCD-40 module over i2c.
In practice, this project can serve as a generic platform for any i2c module that might benefit from a 4 digit display. Potentially, other projects could be built around this architecture.
There is a BOM included: the total cost per unit, as of when it was made in early 2025, was ~90 USD. Most of the cost comes from the SCD-40 module used -- directly integrating one of the modules onto the board should lower that price.
A rough block diagram is below:
The system has two power domains: a 5V domain is used for all digital logic, while the 3V domain is reserved for the seven-segement characters and associated dimming circuit. This separation of power supplies was chosen to both allow for a soft startup sequence (putting less strain on the overall power supply), and to remove some voltage headroom for the LEDs.
The final design was manufactured using JLCPCB's services. A BOM is included with this repo, as well as manufacturing files.
The board can be programmed using the Arduino IDE and a separate ISP over the SPI lines.
Parts
45| Qty | Value | Footprint | References |
|---|---|---|---|
| 5 | 100k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R4, R8, R10, R11, R12 |
| 5 | 100n | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C4, C5, C6, C7, C8 |
| 5 | 1u | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C11, C12, C13, C14, C15 |
| 4 | LDS-C814RI | inv_footprints:LDS-C814RI_LUM | LED1, LED2, LED3, LED4 |
| 2 | 0.1u | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C3, C10 |
| 2 | 10k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R1, R6 |
| 2 | 18p | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C1, C2 |
| 2 | 2N3906 | Package_TO_SOT_THT:TO-92_Inline | Q1, Q2 |
| 2 | 5.1k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R2, R3 |
| 1 | 10u | Capacitor_SMD:C_0805_2012Metric_Pad1.18x1.45mm_HandSolder | C9 |
| 1 | 16MHz | inv_footprints:XTAL_ECS-160-18-23A-EN-TR | Y1 |
| 1 | 1k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R5 |
| 1 | 22k | Resistor_SMD:R_0805_2012Metric_Pad1.20x1.40mm_HandSolder | R9 |
| 1 | 2N3904 | Package_TO_SOT_THT:TO-92_Inline | Q3 |
| 1 | 3v3_or | Jumper:SolderJumper-2_P1.3mm_Open_Pad1.0x1.5mm | JP1 |
| 1 | ATmega328P-A | Package_QFP:TQFP-32_7x7mm_P0.8mm | U1 |
| 1 | Conn_01x02 | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J1 |
| 1 | Conn_01x02 | inv_footprints:MPD_EJ508A | J3 |
| 1 | Conn_02x03_Odd_Even | Connector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical | J2 |
| 1 | MAX7221xNG | Package_DIP:DIP-24_W7.62mm_Socket | U3 |
| 1 | MIC5205-5.0YM5 | Package_TO_SOT_SMD:SOT-23-5 | U4 |
| 1 | MIC5366-3.3YC5 | Package_TO_SOT_SMD:SOT-353_SC-70-5 | U5 |
| 1 | R_Photo | OptoDevice:R_LDR_5.1x4.3mm_P3.4mm_Vertical | R7 |
| 1 | SW_Push | inv_footprints:SKQGADE010 | SW1 |
| 1 | ~ | inv_footprints:scd_40 | U2 |
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Questions
How big is the Co2 7seg PCB?
It measures 82.5 × 35 mm and has 4 copper layers, 1.6 mm thick.
What parts does the Co2 7seg use?
45 parts, built around the ATMEGA328P-AU, MIC5205-5.0YM5, MIC5366-3.3YC5-TR and LDS-C814RI. 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 Co2 7seg KiCad files?
From the morzack/CO2-PCB-Monitor repository on GitHub, at the commit this page was made from: the board is v1/co2_7seg.kicad_pcb and its schematic v1/co2_7seg.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Co2 7seg design in my own project?
Its repository states no licence, so its author keeps all rights: ask morzack before reusing the design.