创建，添加sdram

rt-thread/components/drivers/misc/SConscript

@@ -0,0 +1,35 @@
+from building import *
+
+cwd = GetCurrentDir()
+src = []
+CPPPATH = [cwd + '/../include']
+group = []
+
+if GetDepend(['RT_USING_ADC']):
+    src = src + ['adc.c']
+
+if GetDepend(['RT_USING_DAC']):
+    src = src + ['dac.c']
+
+if GetDepend(['RT_USING_PWM']):
+    src = src + ['rt_drv_pwm.c']
+
+if GetDepend(['RT_USING_PULSE_ENCODER']):
+    src = src + ['pulse_encoder.c']
+
+if GetDepend(['RT_USING_INPUT_CAPTURE']):
+    src = src + ['rt_inputcapture.c']
+
+if GetDepend(['RT_USING_NULL']):
+    src = src + ['rt_null.c']
+
+if GetDepend(['RT_USING_ZERO']):
+    src = src + ['rt_zero.c']
+
+if GetDepend(['RT_USING_RANDOM']):
+    src = src + ['rt_random.c']
+
+if len(src):
+    group = DefineGroup('DeviceDrivers', src, depend = [''], CPPPATH = CPPPATH)
+
+Return('group')