Add library for MCP3204 ADC

CMakeLists.txt

@@ -30,7 +30,8 @@ target_link_libraries(
          pico_multicore
          pio_ws2812
          pico_ssd1306
-         mcp23017)
+         mcp23017
+         mcp3204)
 
 pico_enable_stdio_usb(${PROJECT_NAME} 1)
 pico_enable_stdio_uart(${PROJECT_NAME} 0)

libs/CMakeLists.txt

@@ -1,3 +1,4 @@
 add_subdirectory(pio_ws2812)
 add_subdirectory(pico_ssd1306)
 add_subdirectory(mcp23017)
+add_subdirectory(mcp3204)

libs/mcp3204/CMakeLists.txt

@@ -0,0 +1,10 @@
+file(GLOB mcp3204_SOURCES src/*.cpp)
+
+add_library(mcp3204 STATIC ${mcp3204_SOURCES})
+
+target_include_directories(
+  mcp3204
+  PUBLIC ${CMAKE_CURRENT_LIST_DIR}/include
+  PRIVATE ${CMAKE_CURRENT_LIST_DIR}/include/mcp3204)
+
+target_link_libraries(mcp3204 PUBLIC pico_stdlib hardware_spi)

libs/mcp3204/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2023 Frederik Walk
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the “Software”), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

libs/mcp3204/include/mcp3204/Mcp3204.h

@@ -0,0 +1,16 @@
+#ifndef _MCP3204_MCP3204_H_
+#define _MCP3204_MCP3204_H_
+
+#include "hardware/spi.h"
+
+class Mcp3204 {
+  private:
+    spi_inst *m_spi;
+
+  public:
+    Mcp3204(spi_inst *spi);
+
+    uint16_t read(uint8_t channel);
+};
+
+#endif // _MCP3204_MCP3204_H_

libs/mcp3204/src/Mcp3204.cpp

@@ -0,0 +1,25 @@
+#include "Mcp3204.h"
+
+Mcp3204::Mcp3204(spi_inst *spi) : m_spi(spi) {
+    // Put SPI in 1,1 mode. In this mode date will be clocked out on
+    // a falling edge and latched from the ADC on a rising edge.
+    // Also the CS will be held low in-between bytes as required
+    // by the mcp3204.
+    spi_set_format(m_spi, 8, SPI_CPOL_1, SPI_CPHA_1, SPI_MSB_FIRST);
+}
+
+uint16_t Mcp3204::read(uint8_t channel) {
+    // Byte 1: '00000' to align the ADC's output,
+    //         '1' as start bit,
+    //         '1' for single-ended read,
+    //         '0' for D2 (which is 'don't care' on MCP3204)
+    // Byte 2: Channel bits D1 and D0, followed by '0's as clocks to receive result
+    // Byte 3: Further '0's to receive result
+    uint8_t data_out[3] = {0x06, static_cast<uint8_t>(channel << 6), 0x00};
+    uint8_t data_in[3] = {};
+
+    spi_write_read_blocking(m_spi, data_out, data_in, 3);
+
+    // The 12 result bits are at the end of the ADC's output.
+    return (static_cast<uint16_t>(data_in[1] & 0x0F) << 8) | data_in[2];
+}