initial

.gitmodules

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+[submodule "rpirtscts"]
+	path = rpirtscts
+	url = https://github.com/mholling/rpirtscts

readme.md

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+# modbusmaster
+
+## Disable Bluetooth on RPi3
+
+Add at the end of `/boot/config`:
+
+    dtoverlay=pi3-disable-bt
+
+Remove mentions of `serial0` from `/boot/cmdline`.
+
+
+## Enable rs485 mode
+
+Use the submodule rpirtscts to enable to alternate functions of the related
+pins at the RPi MCU. It is submoduled here, can be found directly at https://github.com/mholling/rpirtscts
+
+    cd rpirtscts
+    gcc -o rpirtscts rpirtscts.c
+    sudo ./rpirtscts on
+
+This needs to be done at every boot.
+
+Kudos to danjperron, cmp. (https://www.raspberrypi.org/forums/viewtopic.php?f=98&t=224533&hilit=rs+485#p1383709)
+
+
+
+## Python snippet to test
+
+    import serial.rs485
+    ser=serial.rs485.RS485(port='/dev/ttyAMA0',baudrate=9600)
+    ser.rs485_mode = serial.rs485.RS485Settings(False,True)
+    ser.write('a test'.encode('utf-8'))
+
+