Added a GPIO to power on/off for external I2C sensor(s) (with LEDs)

Dependencies:   UniGraphic mbed vt100

18-Jun-2018 外部センサの電源オン・オフ機能は下位互換の為に無効になっていました。 この版で再度有効にしました。

Revision:
0:846e2321c637
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/afLib/afSPI.h	Fri Apr 13 04:19:23 2018 +0000
@@ -0,0 +1,28 @@
+/**
+ * Copyright 2015 Afero, Inc.
+ *
+ * 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 AFLIB_AFSPI_H
+#define AFLIB_AFSPI_H
+
+class afSPI {
+    public:
+        virtual void begin() = 0;
+        virtual void beginSPI() = 0;
+        virtual void endSPI() = 0;
+        virtual void transfer(char *bytes,int len) = 0;
+};
+
+#endif
+