Adds guides to make debug cables and open Kuri's torso (#19)

Adds guides to make debug cables and open Kuri's torso

guides/hardware/debug-cable.md

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+---
+layout: guide
+title: Making and using a debug cable
+category: hardware
+tags:
+- debug
+- serial
+---
+
+## Goal
+Make your own serial debug cable, to be able to use the debug console in cases
+where you cannot ssh into Kuri.
+
+## Overview
+Kuri's main board has an open port, that when connected to your
+computer's USB port via a custom TTL cable, allows you to log in to your Kuri.
+
+## Making a debug cable
+For the debug console, we use [3.3V TTL cables from FTDI that have been
+modified with the correct connector]
+(https://www.ftdichip.com/Products/Cables/USBTTLSerial.htm).
+
+Connector housing:  
+Manufacturer: JST  
+Housing Part Number: PHR-3  
+Terminal Part Number: SPH-002T-P0.5L (note: precrimped wire leads are also
+available and will likely be easier to use since you won't have the proper crimper)  
+Pinout:  
+1: TX (output from board) -- Yellow on FTDI cable  
+2: RX (input to board) -- Orange on FTDI cable  
+3: GND -- Black on FTDI cable  
+
+(Alternatively, if you email [email protected] and ask very nicely, someone
+might be willing to lend you a debug cable, particularly if you are in the
+Bay Area.)
+
+## Opening up your Kuri
+
+See the page ``Opening up Kuri's Torso`` for instructions on how to remove
+Kuri's front shell to install the debug cable.
+
+## Connecting the debug cable to Kuri's main board
+
+Once you have the shell open, you should plug the debug cable into the
+only open port that the cable fits into.  You can then route the cable out
+to the opening in Kuri's arm and tape/velcro it down, so that you don't
+have to open Kuri up to use it next time.
+
+## Connecting the debug cable to your computer
+Now that the debug cable is plugged in to Kuri, plug the USB end (using
+a USB extension cable if needed) into your computer's USB port.
+
+## Talking to Kuri from Linux
+If you are
+using a Linux computer, you can using the command-line application `screen`
+to talk to Kuri.  If it is not installed, you can install it using
+```sudo apt install screen```.  
+
+Now connect to Kuri over /dev/ttyUSB0, with a baud rate of 115200:  
+```
+sudo screen /dev/ttyUSB0 115200
+```  
+(If you don't want to use sudo, add your username to the `dialout` group
+in /etc/groups.)
+
+## Talking to Kuri from Windows
+If you are using a Windows computer,
+download [PuTTY](https://www.putty.org/), switch the Connection Type to Serial,
+enter the correct
+COM port under Serial Line, edit Speed to use a baud rate of 115200, and
+the use the Open button to start the session.
+
+## Booting up Kuri
+Now try switching your Kuri on.  You should see a bunch of stuff appear,
+and ideally a prompt to allow you to log in to Kuri.  If you don't get
+the prompt, hopefully there are nice error messages appearing to help you
+understand what's wrong.
+
+

guides/hardware/opening-up-kuri.md

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+---
+layout: guide
+title: Opening Up Kuri's Torso
+category: hardware
+tags:
+- disassembly
+---
+
+## Goal
+Remove Kuri's front shell so that you can get at her main board.
+
+## Overview
+To get at the inside of Kuri's torso, we will remove both arm plates, unscrew
+the screws underneath, then pop the front shells off and unhook the cables
+connecting the shells to the rest of Kuri.
+
+## Removing Kuri's arm plates
+Kuri's arm plates (the grey things to both sides) are only held on by snap-fit.
+You can pop them off by sticking a spudger (or a flat-head screwdriver, or
+even a pen) in the crack between the bottom right (or left) edge of the grey
+plate and the black speaker grill, and wedging it outwards.
+
+Once the arm plates are off, unscrew the screws on the side closest to Kuri's
+front.  Also remove the screw holding the speaker grill on, then slide
+the speaker grill upwards to remove it.  Now unscrew the screw on the side
+closest to Kuri's front that was underneath the speaker grill.
+
+## Removing Kuri's front torso shells
+Kuri's front torso shells (both the white top and the black bottom shells) are
+only held on by snap-fit.  Put Kuri on the ground, facing you, and grab
+both top and bottom shells at once, on both sides.  Pull outwards and towards
+you, wiggling (and deforming slightly) the plates to release all the
+snap-fit attachments.  
+> WARNING: Be careful with the cables that connect the two halves as you pull
+the shells off.  
+
+## Detaching cables
+Detach all the cables between the shells and Kuri's torso.  
+> WARNING: Take careful note of
+the original orientation of the microphone cables (the microphones are the
+things on the other side of the four tiny holes around the neck), since
+those are easy to accidentally re-connect backwards.  Note also how the one
+cable to the depth sensor goes through a cable-guide loop.
+
+## Main board connections
+Now that Kuri's main board is exposed, there are two easy connection points
+of interest: one is the serial debug port, which you can use with a
+custom serial cable (see the ``Making and using a debug cable`` guide).
+The other is the open USB 3.0 port, which you can use to hook up USB devices
+to Kuri's main computer.
+
+## Removing Kuri's rear torso shells
+Kuri's rear torso shells can be removed in much the same way as the front shells--
+unscrew the rest of the screws under the arm plates, then grab the rear
+white and black shells and pull outwards and towards you.