Diff: TouchSense.h

Revision:

0:5a0704efe081

Child:

1:08658b9787d8

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TouchSense.h	Wed Aug 14 09:08:59 2013 +0000
@@ -0,0 +1,95 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2013 Shinichiro Nakamura
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+ 
+#ifndef TOUCHSENSE_H
+#define TOUCHSENSE_H
+
+#include "platform.h"
+#include "gpio_api.h"
+#include "analogin_api.h"
+
+namespace mbed {
+
+/**
+ * A capacitive touch sensor using analog input port.
+ *
+ * Example:
+ * @code
+ * #include "mbed.h"
+ *
+ * TouchSense tp(p18);
+ *
+ * int main() {
+ *     tp.calibration();
+ *     while(1) {
+ *         if (tp.sense()) {
+ *             printf("ON\r\n");
+ *         } else {
+ *             printf("OFF\r\n");
+ *         }
+ *         wait(0.1);
+ *     }
+ * }
+ * @endcode
+ */
+class TouchSense {
+
+public:
+    /**
+     * Create a TouchSense connected to the specified pin
+     *
+     * @param pin TouchSense pin to connect to
+     */
+    TouchSense(PinName pin) : mypin(pin), calval(0) {
+    }
+    
+    void calibration() {
+        uint16_t f1, f2, f3, f4;
+        f1 = execute();
+        f2 = execute();
+        f3 = execute();
+        f4 = execute();
+        calval = (f1 + f2 + f3 + f4) / 4.0;
+    }
+    
+    bool sense() {
+        uint16_t f = execute();        
+        return (calval * 3.00) < f;
+    }
+
+private:
+
+    uint16_t execute() {
+        gpio_init(&gpio, mypin, PIN_OUTPUT);
+        gpio_write(&gpio, 1);
+        __nop();
+        __nop();
+        __nop();
+        __nop();
+        analogin_init(&adc, mypin);
+        return analogin_read_u16(&adc);
+    }
+
+protected:
+    PinName mypin;
+    uint16_t calval;
+    gpio_t gpio;
+    analogin_t adc;
+};
+
+} // namespace mbed
+
+#endif