Understanding the AMBA Protocol: APB, AHB, and ASB Explained
What is a Microcontroller?
A microcontroller is a compact computer on a single VLSI IC chip, containing one or more CPUs, memory, and I/O peripherals. To enable communication between these components, a bus architecture, including address, data, and control buses, is essential.
Introduction to AMBA
The Advanced Microcontroller Bus Architecture (AMBA) is an open standard developed by ARM for connecting and managing functional blocks in a System-on-Chip (SoC). It facilitates efficient communication between components within an SoC, making it a key standard in ASICs and SoCs found in devices like smartphones and IoT products.
AMBA Standards
1. AHB (Advanced High-Performance Bus)
2. ASB (Advanced System Bus)
3. APB (Advanced Peripheral Bus)
4. ATB (Advanced Trace Bus)
5. AXI (AMBA Extensible Interface)
APB (Advanced Peripheral Bus)
APB is used for low-bandwidth peripherals. It operates in three states: IDLE, SETUP, and ACCESS, using signals like PSEL, PCLK, PRESETn, PADDR, PWRITE, PENABLE, PWDATA, and PRDATA. It does not support burst transfers and is ideal for peripherals like UART, Timer, and IO ports.
