added example program for the MPR121 capacitive touch sensor. (#689)

Author: stephenhensley

examples/CMakeLists.txt

@@ -17,6 +17,7 @@ add_subdirectory(GPIO_Input)
 add_subdirectory(GPIO_Output)
 add_subdirectory(MIDI_UART_Input)
 add_subdirectory(MIDI_USBH_Input)
+add_subdirectory(Mpr121)
 add_subdirectory(OLED_SSD130x4WireSPI)
 add_subdirectory(SDMMC_HelloWorld)
 add_subdirectory(SerialPrint)

examples/Mpr121/CMakeLists.txt

@@ -0,0 +1,3 @@
+set(FIRMWARE_NAME Mpr121)
+set(FIRMWARE_SOURCES main.cpp)
+include(DaisyProject)

examples/Mpr121/Makefile

@@ -0,0 +1,12 @@
+# Project Name
+TARGET = Mpr121
+
+# Sources
+CPP_SOURCES = main.cpp
+
+# Library Locations
+LIBDAISY_DIR = ../..
+
+# Core location, and generic Makefile.
+SYSTEM_FILES_DIR = $(LIBDAISY_DIR)/core
+include $(SYSTEM_FILES_DIR)/Makefile

examples/Mpr121/main.cpp

@@ -0,0 +1,56 @@
+/** Reads data from an MPR121 capacitive touch sensor
+ *
+ *  The results are printed over serial.
+ *  Each channel will output either "H" or "L" for whether it's touched,
+ *  and then display in paranthesis the "filtered value" / "baseline value"
+*/
+#include "daisy_seed.h"
+#include <cmath>
+
+using namespace daisy;
+
+DaisySeed hw;
+Mpr121I2C sensor;
+
+int main(void)
+{
+    hw.Init(true);
+
+    System::Delay(100);
+
+    // Initialize MPR121 w/ default settings
+    Mpr121I2C::Config sensor_cfg;
+    sensor.Init(sensor_cfg);
+
+    hw.StartLog(false);
+    uint32_t print_time = System::GetNow();
+
+    while(1) {
+        auto now = System::GetNow();
+
+        if (now - print_time > 100) {
+            // Acquire new data
+            uint16_t touched = sensor.Touched();
+            uint16_t data_base[12];
+            uint16_t data_filt[12];
+            for (int i = 0; i < 12; i++) {
+                data_base[i] = sensor.BaselineData(i);
+                data_filt[i] = sensor.FilteredData(i);
+            }
+
+            // Print the data
+            hw.PrintLine("\nStates:");
+            for (int i = 0; i < 12; i++) {
+                if (i % 4 == 0)
+                    hw.Print("\n");
+                bool sta = (touched & (1 << i)) > 0;
+                hw.Print("%d: %s (%d / %d)\t", i, sta ? "H" : "L", data_filt[i], data_base[i]);
+            }
+            hw.Print("\n");
+            print_time = System::GetNow();
+        }
+
+        // Blink
+        hw.SetLed((now & 511) < 255);
+    }
+}