[Modbusino] - simple modbus rtu library (#2043)

* Add modbusino library + patch + sample + Readme.

Co-authored-by: mikee47 <[email protected]>

.gitmodules

@@ -145,3 +145,7 @@
 [submodule "Libraries.Arduino_TensorFlowLite"]
 	path = Sming/Libraries/Arduino_TensorFlowLite
 	url = https://github.com/slaff/Arduino_TensorFlowLite.git
+[submodule "Libraries.modbusino"]
+	path = Sming/Libraries/modbusino/modbusino
+	url = https://github.com/kmihaylov/modbusino.git
+	ignore = dirty

Sming/Libraries/modbusino/README.rst

@@ -0,0 +1,26 @@
+modbusino RTU Library (modbus slave)
+====================================
+
+modbusino is lightweight RTU `Modbus <https://en.wikipedia.org/wiki/Modbus>`__
+slave library that supports 'read holding registers' and 'write multiple registers' functions.
+Please note that prior to commit 02dff3c (branch Sming, port URL https://github.com/kmihaylov/modbusino)
+a delay may occur after sending a message (more information can be found in the PR thread #2043,
+https://github.com/SmingHub/Sming/pull/2043#issuecomment-615945823).
+
+
+Configuration variables
+-----------------------
+
+
+.. envvar:: RS485_RE_PIN
+
+   Default: 15
+
+   GPIO pin number for RE (Receive-Enable) output.
+
+
+.. envvar:: RS485_TX_LEVEL
+
+   Default: HIGH.
+
+   Active level for RE pin during transmission.

Sming/Libraries/modbusino/component.mk

@@ -0,0 +1,11 @@
+COMPONENT_SUBMODULES := modbusino
+COMPONENT_SRCDIRS := modbusino
+COMPONENT_INCDIRS := modbusino
+
+COMPONENT_VARS += RS485_RE_PIN
+RS485_RE_PIN ?= 15
+COMPONENT_CXXFLAGS += -DRS485_RE_PIN=$(RS485_RE_PIN)
+
+COMPONENT_VARS += RS485_TX_LEVEL
+RS485_TX_LEVEL ?= HIGH
+COMPONENT_CXXFLAGS += -DRS485_TX_LEVEL=$(RS485_TX_LEVEL)

Sming/Libraries/modbusino/samples/generic/Makefile

@@ -0,0 +1,9 @@
+#####################################################################
+#### Please don't change this file. Use component.mk instead ####
+#####################################################################
+
+ifndef SMING_HOME
+$(error SMING_HOME is not set: please configure it as an environment variable)
+endif
+
+include $(SMING_HOME)/project.mk

Sming/Libraries/modbusino/samples/generic/README.rst

@@ -0,0 +1,16 @@
+Modbusino RTU generic sample
+============================
+
+.. highlight:: bash
+
+The sample code provides three element uint16_t array used for the modbus slave registers. These values are printed each second through UART1.
+mbPrint() is triggered on valid write multiple registers (0x10) command.
+
+Several environment variables (envvar:`RS485_RE_PIN` :envvar:`RS485_TX_LEVEL`) can be used for configuration.
+The slave address is defined with envvar:`MB_SLAVE_ADDR`. For example::
+
+   make MB_SLAVE_ADDR=2
+
+These variables can be listed with::
+
+   make list-config

Sming/Libraries/modbusino/samples/generic/app/application.cpp

@@ -0,0 +1,24 @@
+#include <SmingCore.h>
+#include <Debug.h>
+#include <Modbusino.h>
+
+#define ARRLEN 3
+uint16_t mbDataArray[ARRLEN] = {0, 0, 0};
+ModbusinoSlave mbSlave(MB_SLAVE_ADDR, mbDataArray, ARRLEN);
+
+HardwareSerial debugComPort(UART1);
+
+void mbPrint()
+{
+	debugf("Register values, #0: %d, #1: %d, #2: %d", mbDataArray[0], mbDataArray[1], mbDataArray[2]);
+}
+
+void init()
+{
+	debugComPort.begin(SERIAL_BAUD_RATE, SERIAL_8N1, SERIAL_TX_ONLY);
+	debugComPort.systemDebugOutput(true);
+	Debug.setDebug(debugComPort);
+	Debug.start();
+	mbSlave.setup(SERIAL_BAUD_RATE);
+	mbSlave.setRxCallback(mbPrint);
+}

Sming/Libraries/modbusino/samples/generic/component.mk

@@ -0,0 +1,6 @@
+ARDUINO_LIBRARIES := modbusino
+DISABLE_SPIFFS = 1
+
+CONFIG_VARS += MB_SLAVE_ADDR
+MB_SLAVE_ADDR ?= 1
+APP_CFLAGS += -DMB_SLAVE_ADDR=$(MB_SLAVE_ADDR)