Permanent Way Module Hardware
Architecture
The P-Way module is designed to utilise a single microcontroller for most of its digital functionality. The rest of the circuit is principally power conversion, protection and interfacing.
The power domain starts with an external 24 - 36VDC supply. This is polarity protected and fused at 4A with a polyswitch. This is dropped to 14VDC with a switcher for driving rails, point frogs and accessories. This in turn is dropped to 5V for driving servos, and to 3.3V for most of the circuitry.
Major Components
Microcontroller - ST STM32F427
- ARM Cortex-M4 @ 168MHz
- 2MB Flash, 256MB RAM
- SDIO memory card interface
- SPI for display
- Timers for rotary decoding
- PWM for servo positioning
- Ethernet MAC
- UART for WiFi & console
- ADCs for current measurement
- GPIOs and hardware timers for bit banging DCC
- GPIOs for everything else
OLED - ER-OLEDM015-1C-SPI
- 29x29mm OLED
- 128 x 128 resolution
- 18-bit colour
- SSD1351 controller on SPI