10.4  SAMD21 : téléchargement en flash

• Utilise un protocole de déverminage SWD (Serial Wire Debug).
• Le protocole SWD est un protocole série synchrone (SWDIO, SWDCLK).
• Utilisation d’un programmateur indispensable (e.g. ST-LINK v2.1) :

  $ lsusb
  Bus 003 Device 039: ID 0483:374b STMicroelectronics ST-LINK/V2.1
  

• Logiciel libre pour SWD : openocd :

  $ cat st_nucleo_samd21.cfg
  source [find interface/stlink.cfg]
  transport select hla_swd
  set CHIPNAME at91samd21
  set CPUTAPID 0x0bc11477
  source [find target/at91samdXX.cfg]
  $ openocd -f st_nucleo_samd21.cfg \
            -c "init" \
            -c "at91samd bootloader 0" \
            -c "program blink verify" \
            -c "reset" -c "exit"
  Open On-Chip Debugger 0.12.0
  Info : clock speed 400 kHz
  Info : STLINK V2J33M25 (API v2) VID:PID 0483:374B
  Info : [at91samd21.cpu] Cortex-M0+ r0p1 processor detected
  Info : [at91samd21.cpu] target has 4 breakpoints, 2 watchpoints
  [at91samd21.cpu] halted due to debug-request, current mode: Thread 
  xPSR: 0x21000000 pc: 0x0000010c msp: 0x20008000
  ** Programming Started **
  Info : SAMD MCU: SAMD21G18A (256KB Flash, 32KB RAM)
  ** Programming Finished **
  ** Verify Started **
  ** Verified OK **