Implement software spi

config.hpp

@@ -35,7 +35,7 @@ enum class BitOrder {
 
 template <ClockDiv freq = ClockDiv::DIV_128, Mode mode = Mode::MODE_0, Side side = Side::MASTER,
           BitOrder bitOrder = BitOrder::MSB_FIRST, io::P ssPin = io::P::B2, bool pullup = false>
-struct Config {
+struct HardwareConfig {
 	static constexpr auto FREQ = freq;
 	static constexpr auto MODE = mode;
 	static constexpr auto SIDE = side;
@@ -44,4 +44,18 @@ struct Config {
 	static constexpr auto PULLUP = pullup;
 };
 
+template <io::P sckPin, io::P misoPin, io::P mosiPin, io::P ssPin, uint32_t freq = 100'000, Mode mode = Mode::MODE_0,
+          BitOrder bitOrder = BitOrder::MSB_FIRST, uint8_t bits = 8, bool pullup = false>
+struct SoftwareConfig {
+	static constexpr auto SCK_PIN = sckPin;
+	static constexpr auto MISO_PIN = misoPin;
+	static constexpr auto MOSI_PIN = mosiPin;
+	static constexpr auto SS_PIN = ssPin;
+	static constexpr auto FREQ = freq;
+	static constexpr auto MODE = mode;
+	static constexpr auto BIT_ORDER = bitOrder;
+	static constexpr auto BITS = bits;
+	static constexpr auto PULLUP = pullup;
+};
+
 } // namespace spi

software.hpp

@@ -0,0 +1,94 @@
+#pragma once
+
+#include "../clock.hpp"
+
+#include <stdint.h>
+
+#include "../io/io.hpp"
+#include "../util/type.hpp"
+#include "../util/util.hpp"
+
+namespace spi {
+
+template <typename Cfg>
+class Software {
+	static constexpr double calcClockDelay()
+	{
+		constexpr auto staticClockCycles = 10;
+		constexpr auto maxFrequency = F_CPU / staticClockCycles;
+		static_assert(Cfg::FREQ <= maxFrequency, "SPI frequency not achievable using selected clock speed");
+		constexpr auto staticDelay = (1.0 * 1000 * 1000 / maxFrequency);
+		const auto delayUs = ((1.0 * 1000 * 1000 / Cfg::FREQ) - staticDelay) / 2;
+		return (delayUs > 0 ? delayUs : 0);
+	}
+
+	static_assert(Cfg::BITS >= 1 && Cfg::BITS <= 64, "Word size must be in range [1-64]");
+	// clang-format off
+	using word_t = util::conditional_t<Cfg::BITS <=  8, uint8_t,
+	               util::conditional_t<Cfg::BITS <= 16, uint16_t,
+	               util::conditional_t<Cfg::BITS <= 32, uint32_t,
+	                                                    uint64_t>>>;
+	// clang-format on
+
+  public:
+	static void init()
+	{
+		sm_sck = ((Cfg::MODE == Mode::MODE_0 || Cfg::MODE == Mode::MODE_1) ? false : true);
+		sm_ss = true;
+
+		sm_sck.dir(io::Dir::OUT);
+		sm_miso.dir(io::Dir::IN);
+		sm_miso.pullup(Cfg::PULLUP);
+		sm_mosi.dir(io::Dir::OUT);
+		sm_ss.dir(io::Dir::OUT);
+	}
+
+	static word_t transfer(const word_t data)
+	{
+		auto dataIn = word_t{};
+
+		util::for_constexpr(
+		    [&](const auto idx) {
+			    constexpr auto i = idx.value;
+			    constexpr auto bitPos = (Cfg::BIT_ORDER == BitOrder::MSB_FIRST ? Cfg::BITS - i - 1 : i);
+
+			    if constexpr (Cfg::MODE == Mode::MODE_0 || Cfg::MODE == Mode::MODE_2) {
+				    sm_mosi = data >> bitPos & 1;
+				    _delay_us(DELAY_US);
+				    sm_sck.toggle();
+
+				    const auto receivedBit = sm_miso.read();
+				    dataIn |= word_t{receivedBit} << bitPos;
+				    _delay_us(DELAY_US);
+				    sm_sck.toggle();
+			    } else {
+				    sm_sck.toggle();
+				    sm_mosi = data >> bitPos & 1;
+				    _delay_us(DELAY_US);
+
+				    sm_sck.toggle();
+				    const auto receivedBit = sm_miso.read();
+				    dataIn |= word_t{receivedBit} << bitPos;
+				    _delay_us(DELAY_US);
+			    }
+		    },
+		    util::make_index_sequence<Cfg::BITS>{});
+
+		return dataIn;
+	}
+
+	static void select(const bool selectState)
+	{
+		sm_ss = !selectState;
+	}
+
+  private:
+	static io::Pin<Cfg::SCK_PIN> sm_sck;
+	static io::Pin<Cfg::MISO_PIN> sm_miso;
+	static io::Pin<Cfg::MOSI_PIN> sm_mosi;
+	static io::Pin<Cfg::SS_PIN> sm_ss;
+
+	static constexpr auto DELAY_US = calcClockDelay();
+};
+
+} // namespace spi

spi.hpp

@@ -2,6 +2,7 @@
 
 #include "config.hpp"
 #include "hardware.hpp"
+#include "software.hpp"
 
 #include "../io/io.hpp"