diff options
| -rw-r--r-- | .gitignore | 3 | ||||
| -rw-r--r-- | Makefile | 20 | ||||
| -rw-r--r-- | blink.s | 58 | ||||
| -rw-r--r-- | pico_ram_only.ld | 13 |
4 files changed, 94 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..4924391 --- /dev/null +++ b/.gitignore @@ -0,0 +1,3 @@ +*.elf +*.o +*.uf2 diff --git a/Makefile b/Makefile new file mode 100644 index 0000000..3a94707 --- /dev/null +++ b/Makefile @@ -0,0 +1,20 @@ +all: build + +build: blink.uf2 + +# convert ELF file to UF2 file +blink.uf2: blink.elf + elf2uf2 blink.elf blink.uf2 + +# compile +blink.elf: blink.o + arm-none-eabi-ld -T pico_ram_only.ld -o blink.elf blink.o + +blink.o: blink.s + arm-none-eabi-as -o blink.o blink.s + +# flash: build/blink.uf2 +# cp build/blink.uf2 /Volumes/RPI-RP2 + +clean: + rm blink.elf blink.uf2 blink.o @@ -0,0 +1,58 @@ +.syntax unified +.cpu cortex-m0plus +.thumb + +.equ RESETS_BASE, 0x4000c000 +.equ RESET_OFST, 0x0 +.equ RESET_DONE_OFST, 0x8 + +.equ IO_BANK0_BASE, 0x40014000 +.equ GPIO25_STATUS, (IO_BANK0_BASE + 0x0c8) +.equ GPIO25_CTRL, (IO_BANK0_BASE + 0x0cc) + +.equ SIO_BASE, 0xd0000000 +.equ GPIO_OE_SET_OFST, 0x024 +.equ GPIO_OUT_XOR_OFST, 0x01c + +.equ ATOMIC_CLEAR, 0x3000 + +.type main, %function +.global main +main: + + // Deassert GPIO reset + ldr r1, =(RESETS_BASE + ATOMIC_CLEAR) + movs r0, 0x20 // IO_BANK0 is bit 5 + str r0, [r1, RESET_OFST] + + // Wait for GPIO reset to finish + ldr r1, =RESETS_BASE +1: + ldr r2, [r1, RESET_DONE_OFST] + tst r0, r2 + beq 1b + + // Set GPIO25 function to SIO + ldr r1, =GPIO25_CTRL + movs r0, #5 + str r0, [r1, #0] + + ldr r1, =SIO_BASE + + // Set output enable for GPIO 25 + movs r0, #1 + lsls r0, r0, #25 + str r0, [r1, GPIO_OE_SET_OFST] + +loop: + + // Toggle output level for GPIO 25 + str r0, [r1, GPIO_OUT_XOR_OFST] + + // Delay + ldr r2, =400000 +1: + subs r2, r2, #1 + bne 1b + + b loop diff --git a/pico_ram_only.ld b/pico_ram_only.ld new file mode 100644 index 0000000..eb2450e --- /dev/null +++ b/pico_ram_only.ld @@ -0,0 +1,13 @@ +ENTRY(main) + +MEMORY { + FLASH(rx) : ORIGIN = 0x10000000, LENGTH = 2M + SRAM(rwx) : ORIGIN = 0x20000000, LENGTH = 264K +} + +SECTIONS { + .text : { + *(.text) + . = ALIGN(4); + } > SRAM +} |