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  2. Embedded Systems/

Inputs, Outputs, and Timers

Notes Lowlevel Embedded
Table of Contents

Intro
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  • Inputs, Outputs, and Timers form the basis for almost everything embedded systems do.
  • Registers:
    • Registers are the API to the hardware.
    • Are memory mapped, so you can write to a specific address to modify a register.

Binary and Hexadecimal Math
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  • Controlling hardware is just flipping binary bits in memory.
  • Hex comes in handy when we modify the whole variable. Because, each digit in hex corresponds to a nibble(four bits) in binary.
  • Left shifting is similar to multiplying by 2ShiftValue Example:
    • 1 << 3 = 0000 0001 « 3 = 0000 1000 = 8 = 23
  • Right shifting is similar to dividing by 2ShiftValue Example:
    • 8 >> 3 = 0000 1000 » 3 = 0000 0001 = 1 = 8 / 23
  • Last bit can tell us if a number is odd or even Example:
    • 5 = 0000 0101 (odd)
    • 4 = 0000 0100 (even)

References
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