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+# Using a serial interface with U-boot and libreCMC
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+
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+A serial interface (console) provides a means of debugging or
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+unlocking features hidden from the user. Most computing devices
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+have a serial interface whether it is broken out by the manufacture or not.
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+
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+In the case of devices that run libreCMC, a serial console is used
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+to configure U-boot and debug libreCMC if the network interface can't
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+be brought up. These instructions outline the basics of using
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+a serial console with a USB to serial cable.
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+
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+
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+
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+## The basics
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+
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+There are a few different standards for serial interfaces, but here we are
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+providing just the basics. There are 3 different connections that we care
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+about : Transmit (TX), Receive (RX) and Ground (GND). Depending on the
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+serial cable, the color coding could be different. The common coloration
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+is RX is Green, TX is white and GND is black*.
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+
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+These three wires will be connected to a pin header on the board or might need
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+to be soldered to pads. Many device manufactures are kind enough to provide a
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+header and indicate where the serial interface is. Look for silkscreen labeling
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+with : GND, TX, RX. Sometimes additional work is needed to break out a stable
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+serial interface.
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+
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+* Many serial cables ship with the color corresponding to the connection on the board,
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+so TX and RX are effectively reversed.
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+
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+Some routers use the following standard:
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+```
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+ __________________
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+ | | |
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+ | . . . | . | <- Inside of the router (you may need to do some soldering)
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+ |____________|_____|
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+
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+ | | \ \
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+ * GND RX TX
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+```
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+
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+In this case, transmit is in the marked off box.
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+
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+```
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+ _________________
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+ | |
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+ | . . . . |
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+ * |_________________|
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+
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+ | | \ \
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+ GND RX TX Vcc
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+
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+```
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+
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+Some might use a dot to indicate GND, etc...
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+
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+TPE-R1100 example:
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+
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+![alt text](images/serial.png "TPE-R1100 Serial")
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+
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+Warning: NEVER connect the red wire to the device / router! You will most likely fry it because
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+many routers use 3.3V for Vcc instead of the 5V provided by USB.
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+
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+## Getting a console
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+
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+In order to communicate with the device, we need a terminal application to interact with
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+the serial port provided by the USB to serial cable. In this case, we are going to use GNU Screen.
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+Make sure that the GNU Screen package is installed and make sure that your user is part of the
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+`dialout` group.
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+
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+Before we can use the terminal application, we need to know the baud rate at which the serial
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+console will be provided at. With most devices running libreCMC and u-boot, this most likely will
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+be 115200
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+
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+## putting it all together
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+
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+
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+1) Plug in / wire up the serial cable to the board.
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+
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+2) Plug the USB part of the serial cable into an available USB port.
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+
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+3) run `screen /dev/ttyUSB0 115200` or (if you are NOT part of the `dialup` group) `sudo screen /dev/ttyUSB0 115200`
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+
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+4) Power on the device you are connecting to.
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+
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+5) You should see ledgible ASCII text scroll by.
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+
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+
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+# Still needs final review
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+
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