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UNA CSIS |
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The University of North Alabama student chapter of ACM co-sponsored the Hackable Clock V2 Project with the Department of Computer Science and Information Systems. Participants in the extracurricular project received a kit containing all of the electronic components, printed circuit board (pcb), and software tools to assemble and program their own digital alarm clock.
Completed clock (version 2, release 1.0)
The clock is based on the Parallax Propeller chip and the software is written in C. The clock was designed by Dr. Jerkins and was conceived to be “hackable”. The clock's functionality may be extended using the exposed CPU pins (P8-P23) along with 3.3V and 5V power connectors designed into the pcb for enhancing the clock's capabilities (for example: obtain time from GPS, control the clock with a phone app, connect the clock to wireless).
The clock kit is also designed to be easy to assemble. All of the components are through-hole (PTH) soldered. The spacing between components is large enough so that beginners can quickly learn how to be successful soldering. The tools needed to assemble the clock are an inexpensive soldering iron, solder, safety glasses, brass sponge, and a vise or “helping hands” type tool. A solder vacuum or solder wick is also handy to fix any bridged connections.
The basic clock allows the user to set the time (hour and minutes), set an alarm (hour and minutes), set the date (day, month, year, and day of week), and turn on and off the alarm. Other features include a manual snooze, automatic snooze, and display brightness. All of the settings are manipulated using the four buttons and switch on the clock. The clock is powered by a 7.5VDC wall wart and the design includes a super capacitor to maintain the clock configuration during power outages. No enclosure was provided in the kit allowing each participant to create their own.
Participants met regularly throughout the 2021-22 academic year to assemble their clocks (solder components together) and develop the software. Design guidance for the software was provided by Computer Science faculty Dr. Jerkins, Dr. Terwilliger, and Dr. Ray. This web page documents the kit components, data sheets, and software tools for the project.
Printed Circuit Board (pcb)
Front of pcb (V2/R1.1)
Back of pcb (V2/R1.1)
Component datasheets & Clock Schematic
- Microcontroller (CPU)
- EEPROM
- Timekeeping IC (RTC)
- LED display driver
- Level shifter
- LED display
- Super capacitor (RTC backup)
- PCB schematic
Software Design
- Software design flowchart (high level design)
- Bit banging (Wikipedia)
- Bitwise manipulation (Wikipedia)
Software Tools
Important: Carefully read the instructions for installing and configuring the software on the linked pages.- SimpleIDE software, Propeller C compiler and IDE
- Windows 10 serial driver, Install this first for Windows 10 SimpleIDE
- Learn Library Folder, Update to the latest libraries after installing SimpleIDE
- Propeller C tutorials (Parallax)
Soldering Tutorials
Bill of Materials
| Schematic | Item | Description |
|---|---|---|
| IC1 | P8X32A | Parallax Propeller 1 (CPU) |
| IC2 | 24LC256 | 256K I2C serial EEPROM |
| IC3 | DS1302+ | Timekeeping chip w/ scratchpad RAM (real time clock) |
| IC4 | MAX7221CNG | Serial interface 8-digit LED display driver |
| IC5 | SN74AHCT125N | Quad bus buffer w/ tri-state outputs (level shifter) |
| DS1 | LTC-5723HR | 4-digit LED display, red |
| U1 | LM2940-N | 5V LDO regulator, 1A |
| U2 | LM3940 | 3.3V LDO regulator, 1A |
| J1 | PJ-202A | DC power jack |
| J2 | ---- | Programming header, offset, x4 |
| J3 | ---- | 5V header, x2 |
| J4 | ---- | 3.3V header, x2 |
| J5 | ---- | CPU pin header, x8 (P8-P15) |
| J6 | ---- | CPU pin header, x8 (P16-P23) |
| S1 | EG-1218 | SPDT slide switch |
| S2 | 1825910-6 | 6MM tactile switch, thru-hole |
| S3 | 1825910-6 | 6MM tactile switch, thru-hole |
| S4 | 1825910-6 | 6MM tactile switch, thru-hole |
| S5 | 1825910-6 | 6MM tactile switch, thru-hole |
| LS1 | CMI-9605IC-0380T | Audio indicator (spkr) |
| Y1 | HC-49US | 5 MHz quartz crystal |
| Y2 | C-002RX32 | 32.768 KHz crystal |
| C1 | SVLT5R522 | 0.22 F capacitor (RTC backup) |
| C2 | FG MLCC | 0.47 uF capacitor |
| C3 | RDE MLCC | 22 uF capacitor |
| C4 | FG MLCC | 0.47 uF capacitor |
| C5 | FG MLCC | 33 uF capacitor |
| C6 | K MLCC | 0.1 uF capacitor |
| R1 | OL10535E-R52 | 10K, 1/2w, 5%, IC1 pull-up |
| R2 | OL1535E-R52 | 15K, 1/2w, 5%, ISET |
| R3 | CFR50J100R | 100, 1/2w, 5%, S1 |
| R4 | OL10535E-R52 | 10K, 1/2w, 5%, S1 pull-down |
| R5 | CFR50J100R | 100, 1/2w, 5%, S2 |
| R6 | OL10535E-R52 | 10K, 1/2w, 5%, S2 pull-down |
| R7 | CFR50J100R | 100, 1/2w, 5%, S3 |
| R8 | OL10535E-R52 | 10K, 1/2w, 5%, S3 pull-down |
| R9 | CFR50J100R | 100, 1/2w, 5%, S4 |
| R10 | OL10535E-R52 | 10K, 1/2w, 5%, S4 pull-down |
| R11 | CFR50J100R | 100, 1/2w, 5%, S5 |
| R12 | OL10535E-R52 | 10K, 1/2w, 5%, S5 pull-down |