The AMBA APB

• The Advanced Peripheral Bus (APB) is part of the AMBA
• APB is optimized for minimal power consumption and reduced interface complexity
• AMBA APB should be used to interface to any peripherals which are low bandwidth and do not require the high performance of a pipelined bus interface
• The AMBA APB appears as a local secondary bus that is encapsulated as a single AHB or ASB slave device

Advantages of AMBA APB

• Improved performance at high frequency operation
• Performance is independent of the mark space ratio of the clock static timing analysis is simplified by the use of a single clock edge
• No special considerations are require for automatic test insertion
• Many ASIC libraries have a better selection of rising edge registers
• Easy integration with cycle based simulators

APB Bridge

• The AMBA APB Bridge is the only master in the entire APB system
• The APB Bridge functions as a slave in higher level system buses

Bridge Description

• AMBA APB Bridge performs the following functions:
  • Latches the address and holds it valid throughout the transfer
  • Decodes the address and generates a peripheral select, PSELx. Only one select signal can be active during a transfer
  • Drives the data onto APB for a write transfer
  • Drives the APB data onto the system bus for a read transfer
  • Generates a timing strobe, PENABLE for the transfer

Slave Description

• Simple and flexible interface