diff options
| -rw-r--r-- | README.org | 6 | ||||
| -rw-r--r-- | src/boot.S | 11 | ||||
| -rwxr-xr-x | src/main.rs | 28 |
3 files changed, 19 insertions, 26 deletions
@@ -1,4 +1,4 @@ -looks like the start board is a gd32vf103cbt from the tiny print silk-screened on the chip. +looks like the start board is a gd32vf103cbt from the tiny print silk-screened on the chip. [[https://www.tme.com/us/en-us/details/gd32vf103c-start/development-kits-others/gigadevice/][TME]] says it's a gd32vf103d6t6 which means it has 128k flash and 32k sram and 37(!) gpio pins @@ -13,3 +13,7 @@ interrupt vector table is 4096 words starting from the start of flash (~mtvt~ re according to the user manual (pg 51), at least when waking up, the system boots from ~0x0000_0000~ (which is an alias to the start of the main flash, iirc) usb is 2.0 full-speed (12Mbps) + +* USART +On [[https://github.com/tyustli/rt-thread/tree/master/bsp/gd32vf103v-eval][github]] it says that ~uart0~ tx/rx is gpio 9/10 — but that's for the eval board. +See the [[https://github.com/riscv-mcu/GD32VF103_Firmware_Library/tree/master/Examples/USART/Printf][risc-v repository]] for a printf example. diff --git a/src/boot.S b/src/boot.S new file mode 100644 index 0000000..d31e5fe --- /dev/null +++ b/src/boot.S @@ -0,0 +1,11 @@ + .global _start + .section .text.init +_start: + .option push + .option norelax + la gp, __global_pointer$ + .option pop + la sp, _stack_top + + csrr a0, mhartid + tail main diff --git a/src/main.rs b/src/main.rs index c0d41d3..8d95d00 100755 --- a/src/main.rs +++ b/src/main.rs @@ -1,11 +1,11 @@ -#![feature(naked_functions)] - #![no_std] #![no_main] -use core::arch::asm; +use core::arch::global_asm; use gd32vf103_pac::Peripherals; +global_asm!(include_str!("boot.S")); + #[no_mangle] fn main(_hartid: usize) -> ! { // let peripherals = Peripherals::take().unwrap(); @@ -49,28 +49,6 @@ fn main(_hartid: usize) -> ! { } } -#[naked] -#[link_section = ".text.init"] -#[export_name = "_start"] -unsafe extern "C" fn _start() -> ! { - // At boot, the hart is in privilege mode M, mstatus fields MIE - // and MPRV are 0, the pc is set to a reset vector, the mcause - // register specifies why the reset occurred. - // c.f.: [^super::rism2] § 3.4 (Reset) - asm!( - ".option push", - ".option norelax", - "la gp, __global_pointer$", - ".option pop", - - "csrr a0, mhartid", - "la sp, _stack_top", - - "tail main", - options(noreturn) - ) -} - #[panic_handler] fn panic(info: &core::panic::PanicInfo) -> ! { if let Some(loc) = info.location() { |