Bare metal blinker

[avelino]

Hi all. I am trying to run a very simple blinker from scratch (using a custom bootloader on SDCard instead of uboot). I readed in the datasheet about “GPIO_SWPORTA_DR” that “Values written to this register are
output on the I/O signals for Port A if the corresponding data direction bits for Port A are set to Output mode and the corresponding control bit for Port A is set to Software mode. The value read back is equal to the last value written to this register.”

What means that “software mode”? I cannot found any other reference to that “software mode” related to GPIO in the datasheet? Any idea.

Thanks!

[ewp]

@avelino

Any idea.

Hi @avelino here’s a link to the complete code you need using C.

Duo firmware V1.0.5 has been released! (with FreeRTOS source code)

Not elegant, but blink the on-board LED 5 times at start-up using the little core on FreeRTOS: // GPIOC24 is the blue LED. // The datasheet page 536 says: // Configure register GPIO_SWPORTA_DDR and set GPIO as input or output. // When the output pin is configured, write the output value to the // GPIO_SWPORTA_DR register to control the GPIO output level. #define GPIO2 0x03022000 #define GPIO_SWPORTA_DR 0x000 #define GPIO_SWPORTA_DDR 0x004 *(uint32_t*)(GPIO2|GPIO_SWPORTA_DDR)…

[hannahKobain]

You mean, «software mode» is like software-defined (GPIO) function, opposed to being a member of some hardware peripheral function?

[ewp]

Software mode is not defined in the datasheet. However, when used it refers to registers typically changed directly by software, so I think your description is good.