掌機 - Pyra - Assembly - Keyboard Backlight

參考資訊：
https://pyra-handheld.com/wiki/index.php?title=Main_Page

鍵盤背光電路如下，PERIPHERAL-RESET是連接到MCSPI1_CS1(GPIO5_144)，KEYPAD-BL是連接到PWM(GPIO8_230)


MCSPI1_CS1_MUXMODE = 6 (GPIO5_144)


TIMER8_PWM_EVT_MUXMODE = 6 (GPIO8_230)


GPIO5 Clock


GPIO8 Clock


GPIO_OE


GPIO_DATAOUT


main.s

    .global _start

    .equ CM_L4PER_GPIO5_CLKCTRL, 0x4a009078
    .equ CM_L4PER_GPIO8_CLKCTRL, 0x4a009118

    .equ CONTROL_CORE_PAD0_MCSPI1_CS1_PAD1_I2C5_SCL,     0x4a0029c4
    .equ CONTROL_CORE_PAD0_TIMER8_PWM_EVT_PAD1_I2C3_SCL, 0x4a002978

    .equ GPIO5_OE, 0x4805b134
    .equ GPIO8_OE, 0x48053134

    .equ GPIO5_DATAOUT, 0x4805b13c
    .equ GPIO8_DATAOUT, 0x4805313c
 
    .arm
    .text
_start:
    b reset
    b .
    b .
    b .
    b .
    b .
    b .
    b .
     
reset:
    ldr r0, =CM_L4PER_GPIO5_CLKCTRL
    ldr r1, =(1 << 0)
    str r1, [r0]

    ldr r0, =CONTROL_CORE_PAD0_MCSPI1_CS1_PAD1_I2C5_SCL
    ldr r1, =6
    str r1, [r0]

    ldr r0, =CM_L4PER_GPIO8_CLKCTRL
    ldr r1, =(1 << 0)
    str r1, [r0]
    
    ldr r0, =CONTROL_CORE_PAD0_TIMER8_PWM_EVT_PAD1_I2C3_SCL
    ldr r1, =6
    str r1, [r0]
 
    ldr r0, =GPIO5_OE
    ldr r1, =0
    str r1, [r0]

    ldr r0, =GPIO5_DATAOUT
    ldr r1, =0xffffffff
    str r1, [r0]

    ldr r0, =GPIO8_OE
    ldr r1, =0
    str r1, [r0]

    ldr r0, =GPIO8_DATAOUT
    ldr r1, =0xffffffff
    ldr r2, =0x00000000
0:
    eor r2, r1
    str r2, [r0]
    ldr r3, =50000000
1:
    subs r3, #1
    bne 1b
    b 0b
    .end

main.ld

MEMORY
{
  RAM : ORIGIN = 0, LENGTH = 32M
}

SECTIONS
{
  .text : { *(.text*) } > RAM
  .data : { *(.data*) } > RAM
}

Makefile

SD=/dev/sdX

all:
	arm-linux-gnueabihf-as -mcpu=cortex-a7 -o main.o main.s
	arm-linux-gnueabihf-ld -T main.ld -o main.elf main.o
	arm-linux-gnueabihf-objcopy -O binary main.elf main.bin

sd:
	sudo dd if=/dev/zero of=${SD} bs=1M count=10
	sudo dd if=MLO of=${SD} count=2 seek=1 bs=128k
	sudo dd if=main.bin of=${SD} count=4 seek=1 bs=384k

clean:
	rm -rf main.bin main.o main.elf

P.S. /dev/sdX是SD位置

編譯並且燒錄到SD

$ wget https://github.com/steward-fu/archives/releases/download/pyra/MLO

$ make
    arm-linux-gnueabihf-as -mcpu=cortex-a7 -o main.o main.s
    arm-linux-gnueabihf-ld -T main.ld -o main.elf main.o
    arm-linux-gnueabihf-objcopy -O binary main.elf main.bin

$ make sd
    sudo dd if=/dev/zero of=/dev/sdb bs=1M count=10
    10+0 records in
    10+0 records out
    10485760 bytes (10 MB, 10 MiB) copied, 2.61366 s, 4.0 MB/s
    sudo dd if=MLO of=/dev/sdb count=2 seek=1 bs=128k
    0+1 records in
    0+1 records out
    66172 bytes (66 kB, 65 KiB) copied, 0.00214024 s, 30.9 MB/s
    sudo dd if=main.bin of=/dev/sdb count=4 seek=1 bs=384k
    0+1 records in
    0+1 records out
    188 bytes copied, 0.00200567 s, 93.7 kB/s

P.S. MLO是OMAP的X-Loader，司徒是直接從U-Boot編譯後，拿來使用的

將SD插入到Pyra左邊的卡槽，開機後，鍵盤背光就會開始閃爍