1.1. PrimeCell types

Peripherals can be split into four groups related to the method they use to transfer data. These are:

  1. Sequential Data Peripherals (SDP).

    These devices transfer the data sequentially, for example, a single word, byte, nibble at a time. The format of the sequential data is not defined for the transfer larger than the entity size. Peripherals of this type include UARTs and GPIO.

  2. Sequential Block Peripherals (SBP).

    These devices transfer the data sequentially a block of data at a time, for example, multiple words, bytes, nibbles. The format of the data in the block is defined for the transfer and the order in which the blocks are transferred is fixed. Peripherals of this type include video controllers and network interfaces, for example Ethernet, and Universal Serial Bus (USB).

  3. Random Data Peripherals (RDP).

    This group is used to describe memory-like peripherals, where data elements can be accessed in any order. For these devices, a memory model is normally used to give the required validation.

  4. Random Block Peripherals (RBP).

    These devices transfer the data a block at a time. Unlike SBP the blocks can be accessed randomly, but the data within the block is sequentially read out, the format of the data in the block is defined. Peripherals of this type include Serial Peripheral Interface (SPI), Memory Stick, Secure Digital (SD)-Card and MultiMedia Card (MMC).

The PTB is aimed at the sequential data peripherals, sequential block peripherals and random block peripherals.

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