Terminology and Glossary

You can look up some terms in this terminology chapter if you have never heard them before or if they confused you.

• Peripheral: Dedicated hardware unit. On microcontrollers, this can be something like a UART, SPI or timer hardware block.
• Flash: Non-volatile memory which you can use to store your code and constants.
• Stack: Local memory that your program uses as it executes functions
• Heap: Free memory that can be allocated in blocks. Oftentimes not available on microcontrollers.
• Static: Usually refers to the lifetime of a variable. A static variable is valid for the whole program duration.
• RAM: Volatile memory used to store your stack, heap and static variables.
• Processor: Executes your code.
• MCU or Microcontroller: Integrates the processor, peripherals, flash, RAM and is usually placed on a printed circuit board as part of an embedded system.
• Firmware: Software which interacts a lot with hardware. Usually refers to the finished software product on your MCU which runs the embedded system.
• PCB - Printed Circuit Board: This is usually an electronic circuit integrated on a sandwhich structure. Oftentimes, chips, sensors and other components will be soldered on top of the PCB.
• UART - Universal Asynchronous Receiver-Transmitter: Asynchronous serial communication interface which only requires two physical pins, one for transmission and one for reception.
• DMA - Direct Memory Access: Hardware subsystems can access the memory of a system directly without CPU intervention.
• HAL - Hardware Abstraction Layer: High level library providing drivers for the hardware blocks on a microcontroller.