i want to test 'alexa-iot' example. and already test and work normally with DISCO-F746NG board. but this board has Ethernet(wired) only. so i change target board(F401RE) in my project and add 'ESP8266' library. but i can't compile. i saw error message( undefined reference mbedtls_ssl_init and other ).

Where did you find the example? I can't find the 'alexa-iot' project...

https://developer.mbed.org/users/peyo/code/AWS-test/ this is connect with AWS IoT.

First, add the esp8266-driver library. Then, in the code, where it says EthernetInterface (and #include EthernetInterface.h) replace with:

#include "ESP8266Interface.h"
ESP8266Interface net(D8, D2, true);

And pass in SSID and password in the connect call.

But I can't compile the AWS-test program, so I can't verify if it actually works.

thanks for your help. i will try to make my repository. but i don't know how to do. I will share my current project with you.

my project uploaded in repository(https://developer.mbed.org/users/jeonbc/code/aws-iot-example). you have to export it( GCC_ARM/NUCLEO_F401RE ) first. then, add 'CXX_FLAGS += -std=gnu++11' at makefile. you can see error message.

You'll need to set an entropy source, otherwise the ssl functions are not linked in. For TESTING you can define a NULL entropy source by declaring these macros:

MBEDTLS_TEST_NULL_ENTROPY and MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES

I've tested your code with these macros enabled and then the program compiles.

Side-note: you cannot use pin D1/D0 for UART on NUCLEO-F401RE because they are used by USB. Use D8/D2 instead.

ASM_FLAGS += -DMBEDTLS_TEST_NULL_ENTROPY & ASM_FLAGS += -DMBEDTLS_NO_DEFAULT_ENTROPY_SOURCES. added in Makefile. but compile can't. please tell me detail.

These macros need to be set under C_FLAGS and CXX_FLAGS, not under ASM_FLAGS. If you're building with mbed CLI you can also add them under the macros section in mbed_app.json

I succeeded after I followed your instructions. thanks your help.