Improvements to docs.

DISPLAYS.md

@@ -41,7 +41,14 @@ I2C or SPI interfaces. An example is [Adafruit 938][4m].
 Nokia 5110 (PCD8544) displays. [This driver](https://github.com/mcauser/micropython-pcd8544.git)
 is compatible.
 
-# Untested displays
+## Adafruit displays
+
+See [these notes](./ADAFRUIT.md) for wiring details, pin names and hardware
+issues.
+
+# Unlisted displays
+
+## Displays whose controller is listed above
 
 An untested display that uses a supported controller is not guaranteed to work.
 This is because a controller can be connected to the display in a variety of
@@ -49,6 +56,14 @@ ways. In some cases the existing driver can be persuaded to work, sometimes by
 using nonstandard constructor arguments. In other cases the driver itself needs
 to be adapted.
 
+## Other controllers
+
+For an unlisted controller the first step is to see if there is an existing
+driver that can be ported. Adafruit publish CircuitPython drivers for their
+hardware: these are easy to port to MicroPython. Only a minimal subset is
+needed to support these GUI's, with the result that the drivers can be very
+simple. See [this doc](./DRIVERS.md#7-writing-device-drivers) for details.
+
 [1d]: https://github.com/peterhinch/micropython-nano-gui/blob/master/DRIVERS.md#22-drivers-for-ssd1331
 [2d]: https://github.com/peterhinch/micropython-nano-gui/blob/master/DRIVERS.md#21-drivers-for-ssd1351
 [3d]: https://github.com/micropython/micropython/blob/master/drivers/display/ssd1306.py

DRIVERS.md

@@ -791,7 +791,7 @@ SPI 2 and an arbitrary choice of GPIO. All may be changed and soft SPI may be
 used.
 
 | Pyb |  Breakout |
-|:---:|:---------:|
+|:----|:----------|
 | Vin | Vin (1)   |
 | Gnd | Gnd (3)   |
 | Y8  | MOSI (6)  |
@@ -853,7 +853,7 @@ on the underside of the board with the SD card at the top. Each connector has
 pairs of pins which are linked together.
 
 | Pin   | Pyb  | Pin   | Pyb  | Notes                             |
-|:-----:|:----:|:-----:|:----:|:---------------------------------:|
+|:------|:-----|:----- |:-----|:----------------------------------|
 | RST   | Y3   |       |      | Should be open drain (see below). |
 | 3V    | 3.3V |       |      |                                   |
 |  .    |      |       |      |                                   |
@@ -965,7 +965,7 @@ Connections may be adapted for other MicroPython targets. The board may be
 powered from 5V or 3.3V: there is a regulator on board.
 
 | Pyb |      |  L |  R |      | Pyb |
-|:---:|:----:|:--:|:--:|:----:|:---:|
+|:----|:-----|:--:|:--:|:-----|:----|
 | Vin | VIN  |  2 |  1 |      |     |
 |     |      |  4 |  3 |      |     |
 |     |      |  6 |  5 |      |     |
@@ -1160,7 +1160,8 @@ render glyphs instead of Python code.
 
 The following script is useful for testing color display drivers after
 configuring `color_setup.py`. It draws squares at the extreme corners of the
-display and a corner to corner diagonal.
+display and a corner to corner diagonal. The nature of this image makes
+faultfinding much simpler than viewing a garbled GUI screen.
 ```python
 from color_setup import ssd  # Create a display instance
 from gui.core.colors import RED, BLUE, GREEN
@@ -1174,5 +1175,9 @@ ssd.rect(0, 0, 15, 15, RED)  # Red square at top left
 ssd.rect(ssd.width -15, ssd.height -15, 15, 15, BLUE)  # Blue square at bottom right
 ssd.show()
 ```
+If this produces correct output the GUI's can be expected to work.
+
+Authors of device drivers are encouraged to raise an issue or PR so that the
+library can be extended.
 
 ###### [Contents](./DRIVERS.md#contents)

README.md

@@ -7,7 +7,8 @@ small color and monochrome OLED's, color TFT's, ePaper and Sharp units.
 
 The `nano-gui` library is display-only. A library supporting user input is
 [micro-gui](https://github.com/peterhinch/micropython-micro-gui); this comes at
-a cost of a substantially greater RAM requirement.
+a cost of a substantially greater RAM requirement. It supports all displays
+available to nano-gui.
 
 These images, most from OLED displays, fail to reproduce the quality of these
 displays. OLEDs are visually impressive displays with bright colors, wide
@@ -40,9 +41,6 @@ wrap or clipping.
 ![Image](images/seismo.JPG) A mockup of a seismograph screen on an ePaper
 display.
 
-Notes on [Adafruit and other OLED displays](./ADAFRUIT.md) including
-wiring details, pin names and hardware issues.
-
 # Contents
 
  1. [Introduction](./README.md#1-introduction)  
@@ -74,15 +72,17 @@ wiring details, pin names and hardware issues.
  minimising the RAM and flash footprints of the GUI.  
  5. [Old firmware](./README.md#5-old-firmware) For users of color displays who can't run current firmware.
 
-#### [Graph plotting module.](./FPLOT.md)
+#### [Supported displays](./DISPLAYS.md)
 
 #### [Device driver document.](./DRIVERS.md)
 
+#### [Graph plotting module.](./FPLOT.md)
+
 # 1. Introduction
 
 This library provides a limited set of GUI objects (widgets) for displays whose
-display driver is subclassed from the `FrameBuffer` class. Such drivers can be
+display driver is subclassed from the `FrameBuffer` class. The drivers can have
-tiny as the graphics primitives are supplied by the `FrameBuffer` class.
+minimal code as graphics primitives are supplied by the `FrameBuffer` class.
 
 Compatible and tested displays are detailed [here](./DISPLAYS.md). The
 [device driver doc](./DRIVERS.md) provides guidance on selecting the right
@@ -107,10 +107,6 @@ displays:
  * [RA8875 large displays](https://github.com/peterhinch/micropython_ra8875)
  * [SSD1963 large displays](https://github.com/peterhinch/micropython-tft-gui)
 
-Input via pushbuttons or an encoder is offered by
-[micro-gui](https://github.com/peterhinch/micropython-micro-gui). This supports
-all displays supported by nano-gui.
-
 For historical reasons and to ensure consistency, code and documentation for
 my GUI's employ the American spelling of `color`.