stm32f401rc-rs485: Add rs-485 master mode configuration

Documentation/platforms/arm/stm32f4/boards/stm32f401rc-rs485/index.rst

@@ -314,3 +314,69 @@ generated by STM32F401RC-RS485 and transmitted over RS-485::
        [1002]: 	0
        [1003]: 	0
 
+modbus_master
+-------------
+
+Configures the NuttShell (nsh) and enables modbus in msater mode. This
+configuration enables a serial console on USART6. The RS-485 is connected
+to USART2. Follow below precedure to use modbusmaster test aplication, you will
+need a USB to RS-485 converter to connect the board to a PC via RS-485.
+
+PC Configuration:
+
+Download and install diagslave aplication from https://www.modbusdriver.com/diagslave.html.
+
+Check which TTY USB port is being used by you USB to RS-485 converter::
+
+       sudo dmesg
+       [99846.668209] usb 1-1.3: Product: USB Serial
+       [99846.676313] ch341 1-1.3:1.0: ch341-uart converter detected
+       [99846.677454] usb 1-1.3: ch341-uart converter now attached to ttyUSB1
+
+Run the diagslave as below::
+
+       sudo diagslave -a 10 -b 38400 /dev/ttyUSB1
+
+At PC terminal you will see the diagslave application listening to address 10,
+notice that this address is configurable via MODBUSMASTER_SLAVEADDR::
+
+       diagslave 3.4 - FieldTalk(tm) Modbus(R) Diagnostic Slave Simulator
+       Copyright (c) 2002-2021 proconX Pty Ltd
+       Visit https://www.modbusdriver.com for Modbus libraries and tools.
+
+       Protocol configuration: Modbus RTU, frame tolerance = 0ms
+       Slave configuration: address = 10, master activity t/o = 3.00s
+       Serial port configuration: /dev/ttyUSB1, 38400, 8, 1, even
+
+       Server started up successfully.
+       Listening to network (Ctrl-C to stop)
+       Slave  10: readHoldingRegisters from 2, 1 references
+       .......
+
+NuttShell configuration:
+
+Run modbusmaster application at NSH::
+
+       NuttShell (NSH) NuttX-12.4.0
+       nsh> modbusmaster
+       Initializing modbus master...
+       Creating poll thread.
+       Sending 100 requests to slave 10
+       mbmaster_main: Exiting poll thread.
+       Modbus master statistics:
+       Requests count:  100
+       Responses count: 100
+       Errors count:    0
+       Deinitializing modbus master...
+
+The application modbusmaster will send 100 requests, you can check on diagslave::
+
+       Server started up successfully.
+       Listening to network (Ctrl-C to stop)
+       Slave  10: readHoldingRegisters from 2, 1 references
+       Slave  10: readHoldingRegisters from 2, 1 references
+       Slave  10: readHoldingRegisters from 2, 1 references
+       Slave  10: readHoldingRegisters from 2, 1 references
+       Slave  10: readHoldingRegisters from 2, 1 references
+       Slave  10: readHoldingRegisters from 2, 1 references
+       Slave  10: readHoldingRegisters from 2, 1 references

boards/arm/stm32/stm32f401rc-rs485/configs/modbus_master/defconfig

@@ -0,0 +1,77 @@
+#
+# This file is autogenerated: PLEASE DO NOT EDIT IT.
+#
+# You can use "make menuconfig" to make any modifications to the installed .config file.
+# You can then do "make savedefconfig" to generate a new defconfig file that includes your
+# modifications.
+#
+# CONFIG_ARCH_FPU is not set
+# CONFIG_MB_MASTER_FUNC_READWRITE_HOLDING_ENABLED is not set
+# CONFIG_MB_MASTER_FUNC_READ_COILS_ENABLED is not set
+# CONFIG_MB_MASTER_FUNC_READ_DISCRETE_INPUTS_ENABLED is not set
+# CONFIG_MB_MASTER_FUNC_READ_INPUT_ENABLED is not set
+# CONFIG_MB_MASTER_FUNC_WRITE_COIL_ENABLED is not set
+# CONFIG_MB_MASTER_FUNC_WRITE_HOLDING_ENABLED is not set
+# CONFIG_MB_MASTER_FUNC_WRITE_MULTIPLE_COILS_ENABLED is not set
+# CONFIG_MB_MASTER_FUNC_WRITE_MULTIPLE_HOLDING_ENABLED is not set
+# CONFIG_NSH_ARGCAT is not set
+# CONFIG_NSH_CMDOPT_HEXDUMP is not set
+# CONFIG_NSH_DISABLE_IFCONFIG is not set
+# CONFIG_NSH_DISABLE_PS is not set
+CONFIG_ARCH="arm"
+CONFIG_ARCH_BOARD="stm32f401rc-rs485"
+CONFIG_ARCH_BOARD_STM32F401RC_RS485=y
+CONFIG_ARCH_BUTTONS=y
+CONFIG_ARCH_CHIP="stm32"
+CONFIG_ARCH_CHIP_STM32=y
+CONFIG_ARCH_CHIP_STM32F401RC=y
+CONFIG_ARCH_INTERRUPTSTACK=2048
+CONFIG_ARCH_IRQBUTTONS=y
+CONFIG_ARCH_STACKDUMP=y
+CONFIG_BOARD_LOOPSPERMSEC=8499
+CONFIG_BUILTIN=y
+CONFIG_EXAMPLES_BUTTONS=y
+CONFIG_EXAMPLES_BUTTONS_NAME0="SW3"
+CONFIG_EXAMPLES_BUTTONS_NAME1="SW4"
+CONFIG_EXAMPLES_BUTTONS_NAME2="SW5"
+CONFIG_EXAMPLES_BUTTONS_NAME3="SW6"
+CONFIG_EXAMPLES_BUTTONS_NAMES=y
+CONFIG_EXAMPLES_BUTTONS_QTD=4
+CONFIG_EXAMPLES_MODBUSMASTER=y
+CONFIG_EXAMPLES_MODBUSMASTER_SLAVEADDR=10
+CONFIG_HAVE_CXX=y
+CONFIG_HAVE_CXXINITIALIZE=y
+CONFIG_INIT_ENTRYPOINT="nsh_main"
+CONFIG_INPUT=y
+CONFIG_INPUT_BUTTONS=y
+CONFIG_INPUT_BUTTONS_LOWER=y
+CONFIG_INTELHEX_BINARY=y
+CONFIG_MB_RTU_MASTER=y
+CONFIG_MODBUS=y
+CONFIG_MODBUS_MASTER=y
+CONFIG_NSH_ARCHINIT=y
+CONFIG_NSH_BUILTIN_APPS=y
+CONFIG_NSH_FILEIOSIZE=512
+CONFIG_NSH_LINELEN=64
+CONFIG_NSH_READLINE=y
+CONFIG_PREALLOC_TIMERS=4
+CONFIG_RAM_SIZE=98304
+CONFIG_RAM_START=0x20000000
+CONFIG_RAW_BINARY=y
+CONFIG_RR_INTERVAL=200
+CONFIG_SCHED_WAITPID=y
+CONFIG_SPI=y
+CONFIG_START_DAY=5
+CONFIG_START_MONTH=5
+CONFIG_START_YEAR=2014
+CONFIG_STM32_JTAG_SW_ENABLE=y
+CONFIG_STM32_OTGFS=y
+CONFIG_STM32_PWR=y
+CONFIG_STM32_USART2=y
+CONFIG_STM32_USART6=y
+CONFIG_SYSTEM_NSH=y
+CONFIG_TASK_NAME_SIZE=0
+CONFIG_USART2_BAUD=38400
+CONFIG_USART2_PARITY=2
+CONFIG_USART2_RS485=y
+CONFIG_USART6_SERIAL_CONSOLE=y