I am trying to interface with an MSI SDR dongle, using an android app
This device is a clone of the SDRPlay SDR device, and is compatible with it's software and drivers
I am trying to interface with this using an OTG cable and android phone
The android drivers for this can be downloaded from here https://www.sdrplay.com/downloads/
It is in the Android tab under the API/HW – V2.11 (15TH NOV 2017) link (https://www.sdrplay.com/anddl.php)
A possible sample code for this driver can be found here: https://www.sdrplay.com/docs/AndroidIntegrationNote.pdf
Before making the full android program it says the library (libmir_sdr_api.a) should be built into an .so library file using ndk-build
I currently have Android's hello-jni sample project from here: https://github.com/android/ndk-samples/tree/android-mk/hello-jni
I have replaced the jni folder using the Android.mk file, libmir_sdr_api.a, mir_sdr.h, initialization-jni.cpp, demod-jni.cpp and demod-jni.h files mentioned in section 3 of the AndroidIntegrationNote.pdf file I linked above
When I execute ndk-build from the hello-jni project folder, I get he following error:
Android NDK: Found platform level in ./default.properties. Setting APP_PLATFORM to android-25.
Android NDK: android-25 is an alias for android-24. Adjusting APP_PLATFORM to match.
[arm64-v8a] Gdbserver : [aarch64-linux-android] libs/arm64-v8a/gdbserver
[arm64-v8a] Gdbsetup : libs/arm64-v8a/gdb.setup
[x86_64] Gdbserver : [x86_64-linux-android] libs/x86_64/gdbserver
[x86_64] Gdbsetup : libs/x86_64/gdb.setup
[armeabi-v7a] Gdbserver : [arm-linux-androideabi] libs/armeabi-v7a/gdbserver
[armeabi-v7a] Gdbsetup : libs/armeabi-v7a/gdb.setup
[x86] Gdbserver : [i686-linux-android] libs/x86/gdbserver
[x86] Gdbsetup : libs/x86/gdb.setup
make: *** No rule to make target 'jni/initialisation-jni.cpp', needed by 'obj/local/arm64-v8a/objs-debug/mirics-jni/initialisation-jni.o'. Stop.
I am used to compiling NDK code suing Android Studio and cmake so I am not sure what is going on here. I have not been able to link the .a file through cmake either so I thought of giving the driver manufacturer's sample code a try, but it not working either. Is the Android.mk file in pdf file linked earlier incomplete, or am I not building it correctly? These are the contents of the Android.mk file:
# $(call my-dir) returns the local directory which is the jni directory
LOCAL_PATH := $(call my-dir)
# libmir_sdr_api.a – this section creates a version of the Mirics API to be used below
include $(CLEAR_VARS)
LOCAL_MODULE := mir_sdr_api-prebuilt
LOCAL_SRC_FILES := libmir_sdr_api.a
LOCAL_EXPORT_C_INCLUDES := $(call my-dir)
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
# mirics-jni – this section uses the jni C++ source code to build the dynamic library
LOCAL_MODULE := mirics-jni
LOCAL_SRC_FILES := initialisation-jni.cpp demod-jni.cpp
LOCAL_C_INCLUDES := $(call my-dir)
LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib
LOCAL_STATIC_LIBRARIES := mir_sdr_api-prebuilt
include $(BUILD_SHARED_LIBRARY)
Regarding missing jni/initialisation-jni.cpp, you probably have the file jni/initialization-jni.cpp instead.
Also, unfortunately, the document is wrong. You can only use $(call my-dir) easily at the top of the file. Luckily, Android NDK adds the jni directory to includes path for you. Still, to be on the safe side, better write:
# $(call my-dir) returns the local directory which is the jni directory
LOCAL_PATH := $(call my-dir)
# libmir_sdr_api.a – this section creates a version of the Mirics API to be used below
include $(CLEAR_VARS)
LOCAL_MODULE := mir_sdr_api-prebuilt
LOCAL_SRC_FILES := libmir_sdr_api.a
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)
include $(PREBUILT_STATIC_LIBRARY)
include $(CLEAR_VARS)
# mirics-jni – this section uses the jni C++ source code to build the dynamic library
LOCAL_MODULE := mirics-jni
LOCAL_SRC_FILES := initialization-jni.cpp demod-jni.cpp
LOCAL_C_INCLUDES := $(LOCAL_PATH)
LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib
LOCAL_STATIC_LIBRARIES := mir_sdr_api-prebuilt
include $(BUILD_SHARED_LIBRARY)
Finally, pay attention to your build process. You only have one kind of the libmir_sdr_api.a static library, it's built for a 32-bit ARM CPU. Therefore you cannot build your libmirics-jni.so for other architectures. Add
APP_ABIS = armeabi-v7a
to your Application.mk file, or specify
abifilters = armeabi-v7a
in your build.gradle, if you build your library in Android Studio.