77 lines
2.5 KiB
C++
77 lines
2.5 KiB
C++
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#include "system.h"
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#include "usartclass.h"
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static UsartClass * pInstance = nullptr;
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static constexpr unsigned HCLK = 48'000'000u;
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extern "C" void USART1_IRQHandler (void) __attribute__((interrupt));
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void USART1_IRQHandler (void) {
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if (pInstance) pInstance->irq();
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};
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UsartClass::UsartClass(const unsigned int _baud) noexcept : BaseLayer (), tx_ring () {
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pInstance = this;
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// 1. Clock Enable
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RCC.APB2PCENR.modify([](RCC_Type::APB2PCENR_DEF & r) -> auto {
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r.B.USART1EN = SET;
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r.B.IOPDEN = SET;
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return r.R;
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});
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// 2. GPIO Alternate Config - default TX/PD5, RX/PD6
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GPIOD.CFGLR.modify([](GPIOA_Type::CFGLR_DEF & r) -> auto {
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r.B.MODE5 = 1u;
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r.B.CNF5 = 2u; // or 3u for open drain
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r.B.MODE6 = 0u;
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r.B.CNF6 = 1u; // floating input
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return r.R;
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});
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// 4. NVIC
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NVIC.EnableIRQ (USART1_IRQn);
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// 5. USART registry 8.bit bez parity
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USART1.CTLR1.modify([] (USART1_Type::CTLR1_DEF & r) -> auto {
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r.B.RE = SET;
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r.B.TE = SET;
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r.B.RXNEIE = SET;
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return r.R;
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});
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USART1.CTLR2.R = 0;
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//USART1.CTLR3.B.OVRDIS = SET;
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const uint32_t tmp = HCLK / _baud;
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USART1.BRR.R = tmp;
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USART1.CTLR1.B.UE = SET; // nakonec povolit globálně
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}
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void UsartClass::irq () {
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volatile USART1_Type::STATR_DEF status (USART1.STATR); // načti status přerušení
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char rdata, tdata;
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if (status.B.TXE) { // od vysílače
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if (tx_ring.Read (tdata)) { // pokud máme data
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USART1.DATAR.B.DR = (uint8_t) tdata; // zapíšeme do výstupu
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} else { // pokud ne
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// Předpoklad je half-duplex i.e. RS485, jinak jen zakázat TXEIE
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rdata = (USART1.DATAR.B.DR); // dummy read
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USART1.CTLR1.modify([](USART1_Type::CTLR1_DEF & r) -> auto {
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r.B.RE = SET; // povol prijem
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r.B.TXEIE = RESET; // je nutné zakázat přerušení od vysílače
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return r.R;
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});
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}
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}
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if (status.B.RXNE) { // od přijímače
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rdata = (USART1.DATAR.B.DR); // načteme data
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Up (&rdata, 1u); // a pošleme dál
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}
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}
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uint32_t UsartClass::Down(const char * data, const uint32_t len) {
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unsigned n = 0u;
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for (n=0u; n<len; n++) {
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if (!tx_ring.Write(data[n])) break;
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}
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USART1.CTLR1.modify([](USART1_Type::CTLR1_DEF & r) -> auto {
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r.B.RE = RESET;
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r.B.TXEIE = SET; // po povolení přerušení okamžitě přeruší
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return r.R;
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});
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return n;
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}
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