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Microprocessors and -controllers

An MCU is a group of microcontroller units that share a common architecture, design, and often the same core features

  • ARM Cortex-M is a popular MCU family, where multiple manufacturers like STMicroelectronics, NXP, and Microchip produce MCUs that are based on the ARM Cortex-M core.
  • AVR is another MCU family, famously used in the Arduino platform.
  • PIC is a family of MCUs from Microchip Technology, with a range of devices from small 8-bit controllers to more powerful 16-bit and 32-bit versions.

Available Controllers

At least 5 of each:

  • SEEEDSTUDIO XIAO SAMD21 NO HDRS
  • SEEEDSTUDIO XIAO ESP32C3 NO HDRS
  • SEEEDSTUDIO XIAO ESP32S3 NO HDRS
  • SEEED STUDIO XIAO RP2040 ARDUINO
  • ATSAMD11C14A-SSUT
  • ATSAMD21E18A-AUT
  • ATTINY412-SSFR
  • ATTINY1624-SSFR
  • ATTINY3226-SU
  • AVR128DB32-I/PT

QFP mit Beinchen seitlich
TQFP ohne Beinchen
Soic-8 8 Beinchen
Punkt oder Kerbe kennzeichnen Pin 1

Putting code onto it

In-System Programming (ISP)

  • the act of programming a microcontroller while it is already mounted on the board
  • Contrary to Pre-Programming. You program the contro

CMSIS-DAP Devices are all devices that can write programs into a microcontroller's memory using JTAG or SWD. ler before soldering it somewhere.

Serial Peripheral Interface (SPI)

  • A standard synchronous serial communication interface used for short-distance communication between a main device and one or more peripheral devices.
  • synchronous (needs clock signal), serial communication
  • multiple secondary devices are possible
  • full-duplex
  • pins:
    • MOSI (main out secondary in)
    • MISO (main in secondary out)
    • SCK (clock)
    • SS (secondary select): select which secondary device to communicate with

Serial Peripheral Data Interface (SPDI)

  • do not find any source for it

Joint Test Action Group (JTAG)

  • eletronics manufacturers committee
  • they developed a protocol with the same name
  • mostly used for programming ARM cores
  • pins
    • TMS: mode select
    • TCLK: clock
    • TDO: data out
    • TDI: data in
    • nRESET: reset (optional)

Serial Wire Debug (SWD)

  • two-pin variant of the JTAG protocol
  • most common on newer ARM chips
  • pins:
    • swdio: in/out
    • swclk: clock

Unified Program and Debug Interface (UPDI)

  • proprietary
  • single-wire,
  • bi-directional, half-duplex
  • asynchronous
  • can use off-the shelf UART adapters
  • used to program AVR microcontrollers released since 2016, ATTINY412, ATTINY164.
  • more detailed blog article
  • debugging is hidden behind a proprietary interface, but even though you can snoop on the protocol with just a serial adapter and even though the large scale structure of the protocol is known too
  • even more detailed article
  • i did not find out what part of the protocol actually is proprietary and what not.

Difference between microcontroller and -processor

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