modbus: add nxmodbus

NxModbus is a lightweight Modbus protocol stack implementation for NuttX RTOS.

This commit adds:
- nxmodbus stack
- nxmbserver - Modbus Server (Slave) example
- nxmbclient - Modbus Client (Master) tool

Supported Modbus transports:
- ASCII
- RTU over serial port
- TCP
- RAW (ADU) for custom transport implementations

Signed-off-by: raiden00pl <[email protected]>

Author: raiden00pl

examples/nxmbserver/CMakeLists.txt

@@ -0,0 +1,35 @@
+# ##############################################################################
+# apps/examples/nxmbserver/CMakeLists.txt
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more contributor
+# license agreements.  See the NOTICE file distributed with this work for
+# additional information regarding copyright ownership.  The ASF licenses this
+# file to you 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.
+#
+# ##############################################################################
+
+if(CONFIG_EXAMPLES_NXMBSERVER)
+  nuttx_add_application(
+    NAME
+    ${CONFIG_EXAMPLES_NXMBSERVER_PROGNAME}
+    PRIORITY
+    ${CONFIG_EXAMPLES_NXMBSERVER_PRIORITY}
+    STACKSIZE
+    ${CONFIG_EXAMPLES_NXMBSERVER_STACKSIZE}
+    MODULE
+    ${CONFIG_EXAMPLES_NXMBSERVER}
+    SRCS
+    nxmbserver_main.c)
+endif()

examples/nxmbserver/Kconfig

@@ -0,0 +1,33 @@
+#
+# For a description of the syntax of this configuration file,
+# see the file kconfig-language.txt in the NuttX tools repository.
+#
+
+config EXAMPLES_NXMBSERVER
+	tristate "NxModbus Server Example"
+	default n
+	depends on NXMODBUS
+	---help---
+		Enable the NxModbus server example. This example demonstrates
+		how to create a Modbus server (slave) that responds to client
+		requests. Supports RTU, ASCII, and TCP transports with simulated
+		register data.
+
+if EXAMPLES_NXMBSERVER
+
+config EXAMPLES_NXMBSERVER_PROGNAME
+	string "Program name"
+	default "nxmbserver"
+	---help---
+		This is the name of the program that will be used when the NSH ELF
+		program is installed.
+
+config EXAMPLES_NXMBSERVER_PRIORITY
+	int "NxModbus server task priority"
+	default 100
+
+config EXAMPLES_NXMBSERVER_STACKSIZE
+	int "NxModbus server stack size"
+	default DEFAULT_TASK_STACKSIZE
+
+endif # EXAMPLES_NXMBSERVER

examples/nxmbserver/Make.defs

@@ -0,0 +1,25 @@
+############################################################################
+# apps/examples/nxmbserver/Make.defs
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you 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.
+#
+############################################################################
+
+ifneq ($(CONFIG_EXAMPLES_NXMBSERVER),)
+CONFIGURED_APPS += $(APPDIR)/examples/nxmbserver
+endif

examples/nxmbserver/Makefile

@@ -0,0 +1,32 @@
+############################################################################
+# apps/examples/nxmbserver/Makefile
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you 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.
+#
+############################################################################
+
+include $(APPDIR)/Make.defs
+
+MAINSRC = nxmbserver_main.c
+
+PROGNAME  = $(CONFIG_EXAMPLES_NXMBSERVER_PROGNAME)
+PRIORITY  = $(CONFIG_EXAMPLES_NXMBSERVER_PRIORITY)
+STACKSIZE = $(CONFIG_EXAMPLES_NXMBSERVER_STACKSIZE)
+MODULE    = $(CONFIG_EXAMPLES_NXMBSERVER)
+
+include $(APPDIR)/Application.mk