Library Parts Selection
Worked for 8 mins 4 sec
Initial compact placement was too tight around the Pro Micro, encoder, and level shifter, so I’m adjusting the board/placement to remove collisions while keeping the controls accessible.
Thought
I resized the PCB to a compact 60 mm × 105 mm 2-layer board and ran an automatic placement pass with the LCD header targeted to the top edge, the rotary encoder to the right edge, and the Pro Micro oriented for USB access near the bottom.
Work is paused because there are no available ACUs, so I can’t continue executing layout changes right now.
Open items:
- The current placement still needs cleanup: the compact 60 × 105 mm outline is very tight for the Pro Micro footprint, encoder, and LCD interface parts.
- Some components likely need manual spacing adjustments or a slightly larger board, such as ~65–70 mm wide, to avoid collisions and improve routability.
- Placement checks still need to be rerun after adjustment.
Suggested next steps once ACUs are available:
- Increase the board width slightly or manually move the encoder/level shifter away from the Pro Micro.
- Re-run placement checks until there are no overlap/out-of-board issues.
- Route the board and run final layout checks.
Widen and check
Try 65 mm
Show collisions
Keep compact
Run DRC
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Firmware Notes
Target
Arduino Pro Micro (ATmega32U4, 5 V/16 MHz) with 3.3 V I2C F-RAM and detachable Nokia 5110 LCD.
Pin Map
Table
| Function | Pro Micro pin | Net |
|---|---|---|
| I2C SDA | D2 | I2C_SDA |
| I2C SCL | D3 | I2C_SCL |
| LCD SCLK | D15/SCK | LCD_SCK_5V -> level shifter -> LCD_CLK_3V3 |
| LCD MOSI | D16/MOSI | LCD_MOSI_5V -> level shifter -> LCD_DIN_3V3 |
| LCD DC | D4 | LCD_DC_5V -> level shifter |
| LCD CE/CS | D5 | LCD_CE_5V -> level shifter |
| LCD RST | D6 | LCD_RST_5V -> level shifter |
| Encoder A | D7 | ENC_A |
| Encoder B | D8 | ENC_B |
| Encoder switch | D9 | ENC_SW |
Notes
- MB85RC256V address pins A0/A1/A2 are tied low, so the default I2C base address is 0x50.
- WP is tied low for write-enabled operation.
- Use internal pull-ups for encoder A/B/SW or add external pull-ups later if noise requires it.
- Treat password storage as encrypted at rest; do not store plaintext credentials in F-RAM.
Target
Pin Map
Notes
