RISC-V/V003/ch32v003/system.cpp

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#include "CH32V00xxx.h"
extern "C" void SystemInit ();
enum CLKSRC : uint32_t {
CLK_HSI = 0u,
CLK_HSE,
CLK_PLL,
};
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// HSE i HSI mají frekvenci 24 MHz
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void SystemInit(void) {
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RCC.CFGR0.R = 0u; // prescaler OFF
#if USE_HSE
RCC.CTLR.modify([](RCC_Type::CTLR_DEF & r) -> auto {
r.B.HSITRIM = 0x10u;
r.B.HSION = SET;
r.B.HSEON = SET;
r.B.HSEBYP = RESET; // krystal
r.B.CSSON = SET;
r.B.PLLON = RESET;
return r.R;
});
while (RCC.CTLR.B.HSERDY == RESET);
RCC.CFGR0.modify([](RCC_Type::CFGR0_DEF & r) -> auto {
r.B.SW = CLK_HSE;
r.B.PLLSRC = SET; // write only when PLL is off
return r.R;
});
RCC.CTLR.modify([](RCC_Type::CTLR_DEF & r) -> auto {
//r.B.HSION = RESET; // je možné vypnout, ale není to dobrý nápad, pak je nutný unbrick
r.B.PLLON = SET;
return r.R;
});
#else // HSI
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RCC.CTLR.modify([](RCC_Type::CTLR_DEF & r) -> auto {
r.B.HSITRIM = 0x10u;
r.B.HSION = SET;
r.B.HSEBYP = SET;
r.B.CSSON = SET;
r.B.PLLON = SET;
return r.R;
});
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#endif // USE_HSE
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FLASH.ACTLR.B.LATENCY = SET;
RCC.INTR.R = 0x009F0000u; // clear interrupts
while (RCC.CTLR.B.PLLRDY == RESET);
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// USE PLL - zdvojení frekvence, tj. 48 MHz
RCC.CFGR0.B.SW = CLK_PLL ;
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while (RCC.CFGR0.B.SWS != CLK_PLL);
}