the clock that rocks
The rockclock project realizes a clock display based on a 60 element RGB colored LED ring. Therefore its not only a clock, but also some nice eyecandy.
Simply power up the system with a powersupply with at least 2A current. The rockclock powers up and searchs for a valid DCF77 signal while the clock starts with time 0:00. The 12'o'clock point is shown as white dot on the LED ring, hour is yellow, minutes is green and the second is displayed in cyan color.
- STM32F051 controller (STM32 Discovery reference board)
- 60 element WS2812 LED ring
- HC-05 bluetooth USART bridge
- DCF77 receiver module
- GCC Arm 4.9.3 toolchain
- libopencm3
The central hardware is the STM32F051 discovery board, where all other components are connected. The board is powered over the USB debug connector.
The WS2812 LED ring is a 5V device, therefore a level shifter is needed for the data connection to STM32. The 74HCT245 level shifter is connected to Port GPIOB, Pin 0 of STM32 and 5V output is connected to LED data in chain. If further LED chains are needed the STM32 ports GPIOB,1 to GPIOB,7 are usable.
For communication with other systems a bluetooth module is used. The bluetooth module is a HC05 type. The HC05 is connected directly to the STM32 over following port pins:
| Function | Port |
|---|---|
| RX | GPIOA,Pin 2 |
| TX | GPIOA, Pin 3 |
| Config Mode | GPIOA, Pin 1 |
The DCF77 reciever module should provide a TTL digital output. It is connected to Port GPIOC, Pin0.
The software uses the LED on discovery board for debugging purposes, it is connected to GPIOC, Pin 8.
The software is designed around STM32 platform and has following dependencies:
- libopencm3 for low level STM32 register access
- GNU ARM gcc cross compiler chain ver. 4.9.3
- Eclipse internal build
The architecture of the rockclock is a component based model. These components are layered, so that the hardware platform could be replaced without changing the application itself.
- First level components are ordered in subdirectories:
| Component | Description |
|---|---|
| app | The main application |
| com | communication subsystem |
| hal | Hardware abstraction |
| os | Operating system |
| services | Different Services |
- Subcomponents have the following file layout:
| File pattern | Purpose |
|---|---|
| component.c | Implementation of the component |
| component.h | Internal declarations of the component |
| component_config.h | Component configuration definitions |
| component_if.h | Component outer interface |
The HAL abstracts the hardware dependent parts. It contains everything which is platform specific.
The OS realizes simple operating system services like a scheduler.
The Service component provides servcies for other componets like bit operations, PRNG.
The COM component contains the communication stack for different protocols
The APP component realizes the functional application itself.