First commit of proposed 00 Simple MIDI v2

releases/00_Simple_MIDI/v2_prototype/firmware/AnalogueToMIDI.h

@@ -0,0 +1,71 @@
+#ifndef ANALOGUE_TO_MIDI_H
+#define ANALOGUE_TO_MIDI_H
+
+// Class that converts a signal in the range min_ to max_ into 7-bit values 0-127
+// No filtering, but uses hysteresis to avoid jitter
+
+class AnalogueToMIDI
+{
+public:
+	AnalogueToMIDI(int32_t minval_, int32_t maxval_)
+	{
+		minval = minval_;
+		maxval = maxval_;
+		currentMIDIValue = 0;
+		previousMIDIValue = 0;
+	}
+
+	void operator()(int32_t in)
+	{
+		// Rescale input from 0 to 65535
+		if (maxval == minval)
+		{
+			in = maxval;
+		}
+		else
+		{
+			in = ((in - minval) << 16) / (maxval - minval);
+		}
+
+		if (in < 0)
+		{
+			in = 0;
+		}
+		if (in > 65535)
+		{
+			in = 65535;
+		}
+
+		// Naive mapping of in (0-65535) to MIDI (0-127) is (in >> 9)
+		// 0-511     -> 0
+		// 512-1023  -> 1
+		// 1024-1535 -> 2  etc.
+		// Extend these 'windows' by half a window (256) in either direction,
+		// for hysteresis, and update MIDI output value if outside this window.
+		int32_t windowMax = ((currentMIDIValue + 1) << 9) + 255;
+		int32_t windowMin = (currentMIDIValue << 9) - 256;
+
+		if (in > windowMax || in < windowMin)
+		{
+			currentMIDIValue = in >> 9;
+		}
+	}
+	int8_t GetMIDIValueIfNew()
+	{
+		if (currentMIDIValue != previousMIDIValue)
+		{
+			previousMIDIValue = currentMIDIValue;
+			return currentMIDIValue;
+		}
+		else
+		{
+			return -1;
+		}
+	}
+private:
+	int32_t minval, maxval;
+	volatile int8_t currentMIDIValue;
+	int8_t previousMIDIValue;
+};
+
+#endif

releases/00_Simple_MIDI/v2_prototype/firmware/CMakeLists.txt

@@ -0,0 +1,55 @@
+cmake_minimum_required (VERSION 3.13)
+include(pico_sdk_import.cmake)
+project(simple_midi_2 C CXX ASM)
+set(CMAKE_CXX_STANDARD 17)
+pico_sdk_init()
+
+option(OPTIMIZE_SIZE "Optimize for size (-Os) instead of default -O2" OFF)
+
+macro (add_example _name)
+  add_executable(${ARGV})
+  if (TARGET ${_name})
+
+	# Add warnings, in particular about float/double conversion, as it's very easy to end up
+	# with slower double-precision calculations when we only mean to use single-precision float.
+	target_compile_options(${_name} PRIVATE -Wdouble-promotion -Wfloat-conversion -Wall -Wextra -mtune=cortex-m0plus)
+	if (OPTIMIZE_SIZE)
+	  target_compile_options(${_name} PRIVATE -Os)
+	endif()
+	target_link_options(${_name} PRIVATE -Wl,--print-memory-usage)
+
+	# Give oscillator more time to start - some boards won't run if this isn't included
+	target_compile_definitions(${_name} PRIVATE PICO_XOSC_STARTUP_DELAY_MULTIPLIER=64)
+
+	target_include_directories(${_name} PUBLIC ${CMAKE_CURRENT_LIST_DIR})
+    target_link_libraries(${_name} pico_unique_id pico_stdlib  hardware_dma hardware_interp hardware_i2c hardware_pwm hardware_adc hardware_spi)
+	pico_add_extra_outputs(${_name})
+	target_sources(${_name} PUBLIC ${CMAKE_CURRENT_LIST_DIR}/main.cpp)
+
+
+	pico_set_binary_type(${_name} copy_to_ram)
+
+	pico_enable_stdio_usb(${_name} 0)
+  endif()
+endmacro()
+
+
+
+add_example(simple_midi_2)
+
+target_link_libraries(simple_midi_2 pico_multicore  hardware_sync tinyusb_device tinyusb_host tinyusb_board)
+target_sources(simple_midi_2 PUBLIC
+	${CMAKE_CURRENT_LIST_DIR}/usb_descriptors.c
+	${CMAKE_CURRENT_LIST_DIR}/usb_midi_host.c
+	${CMAKE_CURRENT_LIST_DIR}/usb_midi_host_app_driver.c)
+
+# Calibration passthrough test: AudioIn millivolts -> CVOut millivolts
+add_executable(test_passthrough ${CMAKE_CURRENT_LIST_DIR}/test_passthrough.cpp)
+target_compile_options(test_passthrough PRIVATE -Wdouble-promotion -Wfloat-conversion -Wall -Wextra -mtune=cortex-m0plus)
+target_compile_definitions(test_passthrough PRIVATE PICO_XOSC_STARTUP_DELAY_MULTIPLIER=64)
+target_link_options(test_passthrough PRIVATE -Wl,--print-memory-usage)
+target_include_directories(test_passthrough PUBLIC ${CMAKE_CURRENT_LIST_DIR})
+target_link_libraries(test_passthrough pico_unique_id pico_stdlib pico_multicore hardware_sync hardware_dma hardware_interp hardware_i2c hardware_pwm hardware_adc hardware_spi)
+pico_add_extra_outputs(test_passthrough)
+pico_set_binary_type(test_passthrough copy_to_ram)
+pico_enable_stdio_usb(test_passthrough 0)