doc: Add additional USB terms

Add more USB terms to the EC glossary.

BUG=none
BRANCH=none
TEST=none

Change-Id: Ibc2c0d43959749d9527de08337f4a83b41a429ce
Signed-off-by: Keith Short <keithshort@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1778634
Reviewed-by: Jett Rink <jettrink@chromium.org>

2 files changed, 30 insertions, 0 deletions

diff --git a/docs/ec_terms.md b/docs/ec_terms.md
index b34c138f05..6a19b4e055 100644
--- a/docs/ec_terms.md
+++ b/docs/ec_terms.md
@@ -64,6 +64,10 @@
     switching, sensor management, and other functions, offloading these tasks
     from the [AP](#ap).
 
+*   **E-Mark - Electronically Marked Cable** {#emark}
+
+    See the [USB-C documentation](./usb-c.md#emark) for more details.
+
 *   **eSPI - Enhanced Serial Peripheral Interface (Intel)**{#espi}
 
     Intel's synchronous communication interface between the [AP](#ap) and the
@@ -71,6 +75,13 @@
     bandwidth up to 264 Mbps. The full [eSPI Specification] is available from
     Intel.
 
+*   **GMR - Giant Magnetoresistance Sensor** {#gmr}
+
+    A sensor device that detects a magnetic field. These sensors differ from
+    [MAG](#mag) sensors, in that they only detect magnetic fields in close
+    proximity to the sensor. On Chromebooks, GMR sensors are used to detect when
+    the lid is opened.  On convertible Chromebooks, the GMR sensor also detects tablet mode when lid the is opened a full 360 degrees.
+
 *   **GPIO - General Purpose Input/Output**{#gpio}
 
     An individual signal that can independently controlled and read.  GPIOs are
@@ -97,6 +108,10 @@
     of 100 KHz and 400 KHz. The full [I2C Specification] is available from NXP
     (formerly Phillips).
 
+*   **LED - Light Emitting Diode**{#led}
+
+    A Light Emitting Diode is a semiconductor that emits light when current flows through it.
+
 *   **LPC - Low Pin Count bus**{#lpc}
 
     Legacy communication bus between the [AP](#ap) and [EC](#ec). Runs at 33
@@ -172,6 +187,11 @@
     second). Typical use is to provide a debug console to the EC. [RS-232] is
     the protocol standard used by UARTs.
 
+*   **VCONN - Connector Voltage** {#vconn}
+
+    See the [USB-C documentation](./usb-c.md#vconn) for more details.
+
+
 [BC 1.2 Specification]: <https://www.usb.org/document-library/battery-charging-v12-spec-and-adopters-agreement>
 [CrOS Board Info]: <https://chromium.googlesource.com/chromiumos/docs/+/master/design_docs/cros_board_info.md>
 [CEC Wikipedia page]: <https://en.wikipedia.org/wiki/Consumer_Electronics_Control>
diff --git a/docs/usb-c.md b/docs/usb-c.md
index 79b3145bdf..d6327d6dc7 100644
--- a/docs/usb-c.md
+++ b/docs/usb-c.md
@@ -75,6 +75,16 @@ Modes in the EC codebase.
     *   Downstream Facing Port. The USB Data role that is typical for a host
         machine (e.g. device running ChromeOS).
 
+*   E-Mark {#emark}
+    *   Electronically marked cable. A USB-C cable that contains an embedded
+        chip in the cable, used to identify the capabilities of the cable.
+
+*   VCONN {#vconn}
+    *   Connector Voltage. A dedicated power supply rail for [E-Mark](#emark)
+        cables and other accessory functions (such as display dongles, and
+        docks). VCONN re-uses one of the CC1/CC2 signals to provide 5 volt, 1
+        watt, of power.
+
 ## Different PD stacks
 
 Right now platform/ec has two different implementations of USB-C PD stack.