Spac3y/seg7-85A 4-digit 7-segment display driven by an ATtiny85, scrolling a text message across the display.
Attiny85 7seg is an open-source printed circuit board by Spac3y, from the Spac3y/seg7-85 repository on GitHub. It is a 2-layer board of 66 × 66 mm with 31 parts on 31 nets, routed with 171 tracks and 38 vias.
It is built around the ATTINY85-15M, 74HC595 and CC56-12SURKWA. Its parts include 6 capacitors, 6 resistors, 4 ICs, 2 connectors and 2 switches. It belongs with the AVR (ATmega, ATtiny) boards of this library.
A 4-digit 7-segment display driven by an ATtiny85, scrolling a text message across the display.
The ATtiny85 bit-bangs two daisy-chained 74HC595 shift registers to drive a common-anode 4-digit 7-segment display (segments + digit select). A Timer1 CTC interrupt (~3 Hz) shifts the next character of the message into a 4-character rolling buffer, which is refreshed continuously via multiplexing.
| Ref | Part | Qty |
|---|---|---|
| U1 | ATtiny85 (DIP-8) | 1 |
| U3, U4 | 74HC595 shift register (DIP-16) | 2 |
| U2 | 4-digit 7-segment display (CC56-12SURKWA) | 1 |
| R1–R4 | 220Ω (segment current limiting) | 4 |
| R5 | 10kΩ (reset pull-up) | 1 |
| C1–C3 | 10µF decoupling | 3 |
| SW1 | Push button (reset/mode) | 1 |
| J1 | 1x06 pin header | 1 |
| J2 | Molex KK-254 1x02 power connector | 1 |
Full BOM: kicad/attiny85_7seg.csv
attiny-85_code/attiny-85_code.ino — firmware (Arduino/AVR)kicad/ — KiCad schematic, PCB layout, and design fileskicad/changes.md — schematic/PCB change log| Pin | Function |
|---|---|
| PB0 | Shift register data (SER/DS) |
| PB2 | Shift register clock (SRCLK/SHCP) |
| PB3 | Shift register latch (RCLK/STCP) |
| PB4 | Shift register reset (SRCLR/MR) |
Flash attiny-85_code.ino to the ATtiny85 using the Arduino IDE with an ATtiny core installed, via ISP.
| Qty | Value | Footprint | References |
|---|---|---|---|
| 5 | 100nF | Capacitor_THT:C_Disc_D10.0mm_W2.5mm_P5.00mm | C1, C2, C3, C5, C6 |
| 4 | 220 | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R1, R2, R3, R4 |
| 4 | MountingHole_Pad | MountingHole:MountingHole_2.7mm_M2.5_DIN965_Pad_TopBottom | H1, H2, H3, H4 |
| 2 | 10k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | R5, R6 |
| 2 | 74HC595 | Package_DIP:DIP-16_W7.62mm | U3, U4 |
| 2 | SW_Push | Button_Switch_THT:SW_PUSH_6mm | SW1, SW2 |
| 1 | 10uF | Capacitor_THT:CP_Radial_D5.0mm_P2.50mm | C4 |
| 1 | ATtiny85 | Package_DIP:DIP-8_W7.62mm | U1 |
| 1 | CC56-12SURKWA | Display_7Segment:CA56-12SURKWA | U2 |
| 1 | Conn_01x02_Pin | Connector_Molex:Molex_KK-254_AE-6410-02A_1x02_P2.54mm_Vertical | J2 |
| 1 | Conn_01x06_Pin | Connector_PinHeader_2.54mm:PinHeader_2x03_P2.54mm_Vertical | J1 |
| 1 | Gauge_10mm_Type3_SilkScreenTop | Calibration_Scale:Gauge_10mm_Type3_SilkScreenTop | design1 |
| 1 | LOGO | Peter_Image | IMG1 |
| 1 | LOGO | SilkScreen:thehorseishere | LOGO1 |
| 1 | TestPoint_2Pole | TestPoint:TestPoint_2Pads_Pitch2.54mm_Drill0.8mm | TP1 |
| 1 | WEEE-Logo_8.4x12mm_SilkScreen | Symbol:WEEE-Logo_8.4x12mm_SilkScreen | IMG3 |
The 29 most common of 31 parts.
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31 parts, built around the ATTINY85-15M, 74HC595 and CC56-12SURKWA. 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.
From the Spac3y/seg7-85 repository on GitHub, at the commit this page was made from: the board is kicad/attiny85_7seg.kicad_pcb and its schematic kicad/attiny85_7seg.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Its repository states no licence, so its author keeps all rights: ask Spac3y before reusing the design.