Added I2C support for raspi & first rework of debugging

include/sta/bus/spi/device.hpp

@@ -0,0 +1,51 @@
+/**
+ * @file
+ * @brief SPI bus peripheral device.
+ */
+#ifndef STA_CORE_SPI_DEVICE_HPP
+#define STA_CORE_SPI_DEVICE_HPP
+
+#include <sta/bus/device.hpp>
+#include <sta/bus/spi/spi.hpp>
+#include <sta/gpio_pin.hpp>
+
+#include <cstddef>
+#include <cstdint>
+
+
+namespace sta
+{
+    /**
+     * @brief Peripheral device connected via SPI.
+     *
+     * @ingroup sta_core_spi
+     */
+    class SPIDevice : public Device
+    {
+    public:
+        /**
+         * @param intf      %SPI hardware interface
+         * @param csPin     Chip select pin
+         */
+        SPIDevice(SPI * intf, GpioPin * csPin);
+
+        /**
+         * @brief Get %SPI interface settings.
+         *
+         * @return SPI settings
+         */
+        const SPISettings & settings() const;
+
+    protected:
+        void select() override;
+
+        void deselect() override;
+
+    private:
+        SPI * 	    intf_;  /**< %SPI hardware interface */
+        GpioPin *   csPin_; /**< Chip select pin */
+    };
+} // namespace sta
+
+
+#endif // STA_CORE_SPI_DEVICE_HPP