pcb-s16 (pdk-digital-clock)
(for 16-pin PFS154, PFS173, PMS152, or PMS154C)
This PCB design was created with KiCad, and has been shared on OSHPARK. There are also gerber files available in the output/gerber/ directory.
This uses the SLR0394DRC5BD 4-digit 7-segment common cathode 'time' display, which sits over the top of the 74HC595 and the (2) 4x resistor packs. The 74HC595 is used to drive the (4) 7-segment digits, (2) outputs per digit for extra current sink capabilities. The segments themselves are driven directly by the Port B outputs of the Padauk microcontroller.
A single push button is used to set the time, with the following 'user interface':
- A short press will temporarily show the current 'seconds'.
- A medium-press will switch to time config mode. While in config mode:
- A short press will increment the currently selected time value, with rollover.
- A medium-press will switch to the next time value, or exit config mode if on the last time value.
- A long-press will exit config mode.
This digital clock is powered via micro USB cable, although it should work at much lower voltages as well. It isn't really suitable for long-term battery operation, as the LED based 7-segment display consumes enough energy that it wouldn't last very long.
| Ref | Part # | Description | Footprint | Purchase Link | Price | Minimum Purchase |
|---|---|---|---|---|---|---|
| PCB | - | - | - | OSHPARK | $1.033 each | $3.10 for 3 |
| U3 | SLR0394DRA5BD | 4-digit time-mode 7-segment display | - | LCSC C225902 | $0.501 each | $0.501 for 1 |
| U1 | PMS152-S16 | 8-bit Padauk microcontroller | SOP-16 | LCSC C317590 | $0.077 each | $0.39 for 5 |
| U2 | 74HC595D | Serial shift register | SOP-16 | LCSC C93838 | $0.046 each | $0.46 for 10 |
| Y1 | - | 32.767KHz radial cylinder crystal | 2x6mm | LCSC C2236 | $0.045 each | $0.45 for 10 |
| J1 | - | Micro USB connector | - | LCSC C393940 | $0.026 each | $0.52 for 20 |
| SW1 | TS24CA | SPST side-actuated button tactile switch | - | LCSC C393942 | $0.025 each | $0.50 for 20 |
| C2 | - | 10uF capacitor | 0805 | LCSC C92786 | $0.015 each | $0.73 for 50 |
| C3,C4 | - | 20pF capacitor | 0805 | LCSC C309037 | $0.007 each | $0.36 for 50 |
| RN1,RN2 | - | 4x 680 ohm resistor network | 0603_x4 | LCSC C102679 | $0.007 each | $0.35 for 50 |
| C1 | - | 100nF capacitor | 0805 | LCSC C235732 | $0.006 each | $0.30 for 50 |
Total: ~$1.80 each (+/- depending on quantity)
