thermostat/src/dfu.rs

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use core::arch::asm;
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use cortex_m_rt::pre_init;
use stm32f4xx_hal::stm32::{RCC, SYSCFG};
const DFU_TRIG_MSG: u32 = 0xDECAFBAD;
extern "C" {
// This symbol comes from memory.x
static mut _dfu_msg: u32;
}
pub unsafe fn set_dfu_trigger() {
_dfu_msg = DFU_TRIG_MSG;
}
/// Called by reset handler in lib.rs immediately after reset.
/// This function should not be called outside of reset handler as
/// bootloader expects MCU to be in reset state when called.
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#[cfg(target_arch = "arm")]
#[pre_init]
unsafe fn __pre_init() {
if _dfu_msg == DFU_TRIG_MSG {
_dfu_msg = 0x00000000;
// Enable system config controller clock
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let rcc = &*RCC::ptr();
rcc.apb2enr.modify(|_, w| w.syscfgen().set_bit());
// Bypass BOOT pins and remap bootloader to 0x00000000
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let syscfg = &*SYSCFG::ptr() ;
syscfg.memrm.write(|w| w.mem_mode().bits(0b01));
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// Impose instruction and memory barriers
cortex_m::asm::isb();
cortex_m::asm::dsb();
asm!(
// Set stack pointer to bootloader location
"LDR R0, =0x1FFF0000",
"LDR SP,[R0, #0]",
// Jump to bootloader
"LDR R0,[R0, #4]",
"BX R0",
);
}
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}