Update schematic.md

Author: Gadgetoid

hardware/schematic.md

@@ -13,13 +13,14 @@ review-with: jonnya
 
 ## Overview
 
-This page discusses the micro:bit schematic and Bill of Materials (BOM),
-which shows the electrical connections of the micro:bit and the components used in it.
+This page discusses the micro:bit schematic and Bill of Materials (BOM).
 
-The schematic is available from the BBC's [micro:bit hardware repository](https://github.com/bbcmicrobit/hardware)
+The schematic details the electrical connections and components of the micro:bit.
+
+It is available from the BBC's [micro:bit hardware repository](https://github.com/bbcmicrobit/hardware)
 
 If you're looking to make something of your own based on the micro:bit, you might prefer to
-use our ['Reference Design'](/hardware/reference-design/) which is based on a radio module and has space on the layout
+use our ['Reference Design'](/hardware/reference-design/) which is based on a pre-certified nRF51-based radio module and has space on the layout
 for you to add your own components.
 
 ## Schematics
@@ -29,6 +30,7 @@ for you to add your own components.
 - [V2 TBC](#)
 
 ### V2 pinmap
+
 Whilst we work on the publication of the schematic for the latest revision, here is the pinmap and allocation of the nRF52833
 
 | GPIO on nRF52833 | Allocation          | KL27 Landing                             | Edge Connector name |
@@ -69,20 +71,18 @@ Whilst we work on the publication of the schematic for the latest revision, here
 
 ## Key Features
 
-Below, we've extracted some useful details about the hardware that anyone implementing
+We've extracted some useful details about the hardware that anyone implementing
 software for the micro:bit, interfacing to it, or designing an add-on board for it
 should find useful.
 
 
 ### LEDS
 
-The LED matrix is physically layed out as a 5x5. On the <span class="v2">V2</span> board this is implemeted as a 5x5 matrix, but in the <span class="v1">v1</span>, this is implemented as a
-scanned matrix of 9x3 (i.e. 9 colums by 3 rows). Row 2 Col 8, and Row 2 Col 9 are not used.
+The LEDs are physically laid out as a 5x5 matrix. On the <span class="v2">V2</span> board this is implemeted as a 5x5 matrix, but in the <span class="v1">v1</span>, this is implemented as a scanned matrix of 9x3 (i.e. 9 colums by 3 rows). Row 2 Col 8, and Row 2 Col 9 are not used.
 
-The LED matrix is driven via a high-speed multiplex generated by application processor software.
-This software also uses the LED Row and Col pins to implement the light sensing feature, as such you may see a difference in sensitivity between borad revisions.
-Some of the Columns appear on the edge connector, so if you want to use extra GPIO pins,
-you have to disable the display in software.
+The LED matrix is multiplexed at high-speed by a software driver.
+This software also uses the LED Row and Col pins to implement the light sensing feature, as such you may see a difference in sensitivity between board revisions.
+Some of the Columns appear on the edge connector. If you want to use these as extra GPIO pins, you must disable the display in software.
 
 
 ### Interface
@@ -96,41 +96,40 @@ the drag and drop code load interface. It also provides a Connected Device Class
 a serial port interface to be used across the USB.
 
 The interface processor also contains an on-board regulator that steps down the USB voltage
-to 3.3V suitable for powering the rest of the micro:bit, and you can draw 120mA<span class="v1">v1</span>/300mA<span class="v2">V2</span> from this
-processor regulator. A TVS device is fitted to suppress ESD spikes and out of range voltages
+to 3.3V suitable for powering the rest of the micro:bit. You can draw 120mA<span class="v1">v1</span>/300mA<span class="v2">V2</span> from this  regulator. A TVS device is fitted to suppress ESD spikes and out-of-range voltages
 that could be present on the USB connector.
 
 This processor does not have any connection to the GPIO pins on the micro:bit.
 
 ### Sensors
 
 There is one combined motion sensor IC on the micro:bit, that contains an accelerometer and a magnetometer. The accelerometer
-measures acceleration in 3 axies, and the magnetometer can be used as a compass, as well as a magnetic field detector.
+measures acceleration in 3 axes. The magnetometer can be used as a compass or a magnetic field detector.
 
-The device is connected to the application processor [I2c bus](../i2c/), and for the <span class="v1">v1</span> revision this [I2c bus is also shared](../i2c-shared/) to two pins on the edge connector. I2C pullup resistors are pre-fitted on the board.
+The device is connected to the application processor [I2c bus](../i2c/), and for the <span class="v1">v1</span> revision this [I2c bus is also connected](../i2c-shared/) to two pins on the edge connector. I2C pullup resistors are pre-fitted on the board.
 
 The magnetometer can generate one processor interrupt for the application processor, and the
 accelerometer can generate two different processor interrupts for the application processor.
 
-Note, the physical orientation of this IC is important for binary compatibility with the driver
-code in the application processor, which assumes a particular physical orientation in it's calculations.
+Note: the physical orientation of this IC is important for binary compatibility with the driver
+code in the application processor, which assumes a particular physical orientation in its calculations.
 
 
 
 ### Power Supply
 
-Power to the micro:bit can be provided by 3 sources: The USB, the battery connector, and the 3V pad
+Power to the micro:bit can be provided by 3 sources: USB, the battery connector, or the 3V pad
 on the edge connector.
 
-For USB powering, the KL26 interface processor has an on-board regulator that brings the external
+For powering via USB, the KL26 interface processor has an on-board regulator that brings the external
 USB voltage into the correct range for the micro:bit board.
 
 A low-Vf diode (in this case about 0.23V max) is used to switch between sources. The diode prevents back-powering
 of any source from any other source.
 
 Care should be taken if powering the micro:bit from the 3V pad on the edge connector, as the trace
-from that pad is connected directly to the IC's on the board. Please check the datasheets for the
-appropriate IC's for their maximum tolerable voltages.
+from that pad is connected directly to the ICs on the board. Please check the datasheets for the
+appropriate ICs for their maximum tolerable voltages.
 
 
 
@@ -140,7 +139,7 @@ The main application processor runs both the runtime code and user code, as a si
 
 Code is loaded into this processor via the interface processor.
 
-Communications via USB serial is done via the interface processor.
+USB serial communication is done via the interface processor.
 
 All GPIO pins on the [edge connector](../edgeconnector/) are serviced by this application processor.
 
@@ -154,25 +153,26 @@ The nRF52<span class="v2">V2</span> features additional NFC functionality on P0.
 
 The edge connector is the main interface to external components attached to the micro:bit.
 
-This interface has a range of digital, analog, touch, pwm, and serial communications interfaces.
+This interface has a range of digital, analog, touch, PWM, and serial communications interfaces.
 
-10Mohm weak pull-up resistors are fitted on P0 P1 and P2 for use in touch sensing mode, where they
-provide a weak pull-up to the supply providing a default high input and the user touching the GND
-pad pulls the pin down towards 0V, providing a low input. When in non touch modes, these
+10Mohm weak pull-up resistors are fitted on P0, P1 and P2 for use in touch sensing mode. They
+provide a weak pull-up to the supply, providing a default high input. The user touching the GND
+pad and a given pin pulls the pin down towards 0V, providing a low input. When in non touch modes, these
 pads have stronger internal pull-downs enabled in the software, so that the default input state
 when not connected is 'low'.
 
-Guard pins are provided both sides of the 3V and GND pads, so that shorting by crocodile clips
+Guard pins are provided on both sides of the 3V and GND pads, so that shorting by crocodile clips
 does not degrade the features of the device by causing spurious inputs.
 
 Both the front and the back of each of the 5 round ring pads are electrically connected.
 
 A number of pins have alternate assigned functions for use by the micro:bit, many of these
 can be disabled in software to gain more general purpose IO pins.
 
-The <span class="v2">V2</span> board revision has a notched edge connector to make it easier to connect crocodile clips and wire etc. This does not affect compatibility with peripherals with edge connector sockets.
+The <span class="v2">V2</span> board revision has a notched edge connector to make it easier to connect crocodile clips or wire. This does not affect compatibility with existing peripherals using edge connector sockets.
 
 ### Dimensions
+
 The specific dminensions of the board are
 -  51.60mm(w) 42.00mm(h) 11.65mm(d)
 - JST connector to board 5.50mm