get mqtt_client building

CmakeLists.txt

@@ -41,3 +41,65 @@ target_link_libraries(wifi_scan
     )
 
 pico_add_extra_outputs(wifi_scan)
+
+
+# Define the host name of the MQTT server in an environment variable or pass it to cmake,
+# e.g. cmake -DMQTT_SERVER=myserver ..
+
+if ((NOT MQTT_SERVER) OR (NOT MQTT_USERNAME) OR (NOT MQTT_PASSWORD))
+    message("Missing MQTT_SERVER or MQTT_USERNAME or MQTT_PASSWORD")
+    return()
+endif()
+
+set(MQTT_SERVER "${MQTT_SERVER}" CACHE INTERNAL "MQTT server")
+set(MQTT_USERNAME "${MQTT_USERNAME}" CACHE INTERNAL "MQTT user name")
+set(MQTT_PASSWORD "${MQTT_PASSWORD}" CACHE INTERNAL "MQTT password")
+set(WIFI_SSID "${WIFI_SSID}" CACHE INTERNAL "wifi ssid")
+set(WIFI_PASSWORD "${WIFI_PASSWORD}" CACHE INTERNAL "wifi password")
+
+# Set path to the certificate include file
+if (NOT MQTT_CERT_PATH)
+    set(MQTT_CERT_PATH ${CMAKE_CURRENT_LIST_DIR}/certs/${MQTT_SERVER})
+endif()
+
+# Set the name of the certificate include file
+if (NOT MQTT_CERT_INC)
+    set(MQTT_CERT_INC mqtt_client.inc)
+endif()
+
+set(TARGET_NAME mqtt_client)
+
+add_executable(${TARGET_NAME}
+    mqtt_client.c
+    )
+
+target_link_libraries(${TARGET_NAME}
+    pico_stdlib
+    hardware_adc
+    pico_cyw43_arch_lwip_threadsafe_background
+    pico_lwip_mqtt
+    pico_mbedtls
+    pico_lwip_mbedtls
+    )
+
+target_include_directories(${TARGET_NAME} PRIVATE
+    ${CMAKE_CURRENT_LIST_DIR}
+    ${CMAKE_CURRENT_LIST_DIR}/.. # for our common lwipopts or any other standard includes, if required
+    )
+
+target_compile_definitions(${TARGET_NAME} PRIVATE
+    WIFI_SSID=\"${WIFI_SSID}\"
+    WIFI_PASSWORD=\"${WIFI_PASSWORD}\"
+    MQTT_SERVER=\"${MQTT_SERVER}\"
+    MQTT_USERNAME=\"${MQTT_USERNAME}\"
+    MQTT_PASSWORD=\"${MQTT_PASSWORD}\"
+    )
+
+pico_add_extra_outputs(${TARGET_NAME})
+
+# Ignore warnings from lwip code
+set_source_files_properties(
+    ${PICO_LWIP_PATH}/src/apps/altcp_tls/altcp_tls_mbedtls.c
+    PROPERTIES
+    COMPILE_OPTIONS "-Wno-unused-result"
+    )