major bus and device used today in embbed hardware

1. bus

    HPI: host port interface, 16bit high speed "in board" bus, mainly used by TI DSP which will expose DSP memory to another CPU, resulting in controlling by another CPU.

    memory bus: usually it is a standalone bus connecting to DDR slot. But sometimes other device may be connected on it too. Usually A embbed CPU may have 2 ports available to connect external high speed bus.

    PCI/E, ISA: "in board" bus connecting peripherals, high speed.

    SPI, I2C:"in board" serial bus, not very fast.

    UART, McASP, McBSP: "in board" serial bus, fast.

    USB, serial: "out board" bus used to connect device. 

2. devices

    RTC: real time clock.

    GP Timer: used to generated time interrupt.

    Watch Dog: a special timer to watch system state.

    E2ROM: electric writable rom.

    DMA/EDMA controller: help transfer data between memory and device without CPU.

    F-RAM: a fast RAM would not lose its state when power is off, expensive but useful to protect important data.

    super capacitance: used to keep system power on for a few seconds, when main power is off.

    NOR flash: high speed flash but expensive, sometimes code on it could be executed in place, that is in flash not in memory.

    NAND flash: large but cheap flash device, but have block corrupt problem if power is lost when a block is being writing.

3 evaluate the system capability:

    CPU: look at the pins it have for every special purpose, or special ports. For eg, if it have 40 pins dedicating to video decoder, it have a high bandwidth for video. If it keeps some high speed port, maybe another CPU could be connected to it resulting
in a double CPU system.

    Memory: Bus width.

    Hardware Timer: more timers should be used if a real time OS is running on it.

    GPIO pins: decides if it suits high speed data gathering at field.

    Standard Bus: Such as PCI-E, decides if it is easy to extend the hardware unit.