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Diffstat (limited to '_log/arduino-due.md')
| -rw-r--r-- | _log/arduino-due.md | 26 |
1 files changed, 8 insertions, 18 deletions
diff --git a/_log/arduino-due.md b/_log/arduino-due.md index 0d4f495..f604e89 100644 --- a/_log/arduino-due.md +++ b/_log/arduino-due.md @@ -4,25 +4,15 @@ date: 2024-09-16 layout: post --- -Notes on programming ATSAM3X8E chips (Arduino Due) without bootloader. Tested -on OpenBSD. +Notes on programming bare-metal ATSAM3X8E chips (Arduino Due) using Serial Wire +Debug (SwD) protocol. ## Toolchain -Need to bypass embedded bootloader—requires hardware programmer that speaks -Serial Wire Debug (SWD). ST-LINK/V2 works as SWD-USB adapter. - -OpenOCD translates commands to binary sequences the chip understands. Runs -telnet server on startup for issuing commands. - -ARM GNU Compiler Toolchain for compiling C programs. Both OpenOCD and ARM -toolchain available on OpenBSD. +ST-LINK/V2 programmer, OpenOCD, ARM GNU Compiler Toolchain. ## Electrical connections -Arduino Due exposes ATSAM3X8E's SWD interface via DEBUG port. ST-LINK/V2 -connects there. - <table style="border: none; width: 100%;"> <tr style="border: none;"> <td style="border: none; width: 50%; vertical-align: top; background-color: transparent;"> @@ -41,8 +31,7 @@ ST-LINK/v2 programmer connects to that to communicate with the chip. ## Upload procedure -Sample LED blink program with OpenOCD config and linker scripts in tarball -below. +Build. Magic is in the script.ld linker script. ``` $ arm-none-eabi-gcc -mcpu=cortex-m3 -mthumb -T script.ld \ @@ -51,7 +40,8 @@ $ arm-none-eabi-gcc -mcpu=cortex-m3 -mthumb -T script.ld \ -o a.elf main.c ``` -Upload: + +Upload using OpenOCD: ``` $ openocd -f openocd-due.cfg @@ -81,8 +71,8 @@ Program goes in flash0, so set GPNVM1=1 to boot our code instead of bootloader. ## Linker script notes -Vector table must be at first flash address--mandatory for ARM chips unless -using VTOR register for relocation. +Vector table must be at first flash address--required for ARM chips unless +relocated using VTOR register. First vector table entry: stack pointer. Initialize to highest memory location (ATSAM3X8E has descending stack). |