Project:USB Disco Dance Floor/v1/firmware

USB Disco Dance Floor v1 Firmware
Created	2011-03-31
Members	DMI
Project Status	Prototyping

Introduction

The firmware will be responsible for listening for serial commands, and then acting upon them. This will primarily involve changing the display.

Data types

Colour spec

The board reports the number of colours it supports at reset time. The colour(s) in a one-colour board will be referred to as R, in a three-colour board as RGB, and in a four-colour board as RGBU. This is because of the suggested LED choices of Red, Green, Blue, and Ultraviolet. The board also reports the number of bits (n) that it can use for setting the brightness of each colour LED.

A colour spec consists of n bits of R, followed by n bits of G, B, and U (as appropriate). If the total number of bits is not a multiple of 8, it will be right-padded with zeroes.

Examples:

• 4 bpc and 4 colours would lead to a bit pattern of: RRRRGGGG BBBBUUUU.
• 4 bpc and 3 colours would have a bit pattern of: RRRRGGGG BBBB0000
• 12 bpc and 3 colours would have a bit pattern of: RRRRRRRR RRRRGGGG GGGGGGGG BBBBBBBB BBBB0000
• 3 bpc and 3 colours would have a bit pattern of: RRRGGGBB B0000000

Co-ordinate

A co-ordinate consists of four two-bit values packed into a single byte, with the bit pattern: xxyywwhh. Co-ordinates of (0,0) are at the top-left of the module, and increase downwards and rightwards. Note that the ww and hh bits may be ignored.

Scroll spec

A scroll spec consists of two two-bit values and two one-bit values packed into a single byte, with the bit pattern: xxyy0w0h. The number of pixels to scroll along the X and Y axes is specified by xx and yy, and the direction is negative along the X/Y axis if w or h are set, respectively.

Ordering

When commands refer to regions of the floor and some ordering of the data is needed it will be sorted in a fixed format, with the X co-ordinate increasing until it would fall outside the region. The X co-ordinate is then reset and the Y co-ordinate increased by 1, until the region is defined.

For example, the region: (1, 0) to (2, 2) would be ordered as follows: (1, 0), (2, 0), (1, 1), (2, 1), (1, 2), (2, 2). The code for this algorithm might look something like:

for j in range(y, h+1):
  for i in range(x, w+1):
    output(pixel[x][y])

and going back the other way:

pos=0
while (col = read()):
  i = x + (pos % (1+w-x))
  j = y + (pos / (1+w-x))
  pixel[x][y] = col
  ++pos

Commands

Commands start with a one-byte identifier, followed by zero or more data bytes. The number of data bytes is command-specific. The device should not output any data unless specified below. Note that "data in" and "data out" are from the point of view of the device.

Status/Diagnostic Commands

Command	Details		Min version
00	Reset		1.0
	Data in: None	Data out: 6 bytes: hardware version (2), firmware version (2), capabilities (2)
	Resets the board to an initial state, with all pixels off. The board sends four bytes representing its hardware and firmware versions (2 bytes each), followed by 2 bytes for hardware details. This command also resets the board ID to 0xFFFF (i.e. unset). The high nybble of the first hardware info byte is the number of different colours supported (0x1, 0x3, or 0x4) and the low nybble is whether sensors are supported (0x1 for yes). The high nybble of the second byete specifies the number of bits needed to specify LED brightness. If this is different for different colours, the firmware will handle scaling. The low nybble does the same for sensor resolution. Note that, for the time being, resolutions should be a power of 2 (0x1, 0x2, 0x4, 0x8).
01	Identify		1.0
	Data in: 2 bytes: board ID	Data out: 1 byte: 0x00
	Informs the board of its two-byte board ID for this session. Note that board IDs 0x0000 and 0xFFFF are reserved. The board will respond with 0x00 (success).
02	Ping		1.0
	Data in: None	Data out: 3 bytes: 0x00, board ID (2)
	Checks connectivity with the board. The board will respond with 0x00 (success) followed by its two-byte board ID.
03	Query neighbours		1.2?
	Data in: None	Data out: 8 bytes: top neighbour ID, right ID, bottom ID, left ID
	Asks the board to search for its immediate neighbours. The board will respond with 8 bytes representing the two-byte IDs of its neighbours, starting with its "top" connection and proceeding clockwise. If no neighbour is found in a given position, 0x0000 is returned. If a neighbour is found but it has not been given an identifier for this session, it will return 0xFFFF. This should allow the controller software to automatically detect the layout of the floor.
0E	Display static test pattern		1.0
	Data in: 1 byte: pattern to display	Data out: 1 byte: 0x00
	A static test pattern will be displayed, as selected by the one-byte argument. A list of patterns is given below: 00 - All white 01 - All red 02 - All green 03 - All yellow 04 - All blue 05 - All magenta 06 - All cyan 07 - All 50% white 08 - Checkerboard: (0,0)=red; (0,1)=cyan 09 - Checkerboard: (0,0)=cyan; (0,1)=red 0A - Checkerboard: (0,0)=green; (0,1)=magenta 0B - Checkerboard: (0,0)=magenta; (0,1)=green 0C - Checkerboard: (0,0)=blue; (0,1)=yellow 0D - Checkerboard: (0,0)=yellow; (0,1)=blue 0E - Checkerboard: (0,0)=white; (0,1)=black 0F - Checkerboard: (0,0)=black; (0,1)=white 10 - RGB fade, (0,0) = red; (3,0) = green; (0,3) = blue; (3,3) = magenta
0F	Display animated test pattern		1.0
	Data in: 1 byte: pattern to display	Data out: 1 byte: 0x00
	An animated test pattern will be displayed, as selected by the one-byte argument. A list of patterns is given below: 00 - clockwise spiral chase (white), starting at (0,0) 01 - clockwise spiral (white), starting at (0,0); then black spiral once complete

Simple Display Commands

Command	Details		Min version
10	Clear module		1.0
	Data in: None	Data out: None
	Clears the entire module, resetting all pixels to black.
11	Write module		1.0
	Data in: 16 colour specs	Data out: None
	Set the intensities of all pixels on the module. Note: if colour specs contain zero-padding, this should not be removed in the data for this command.
18	Clear row		1.0
	Data in: 1 byte: row number	Data out: None
	Clears the given row, resetting all pixels to black.
19	Write row		1.0
	Data in: 1 byte: row number, 4 colour specs	Data out: None
	Set the intensities of all pixels in the given row. The data is ordered with increasing X. Note: if colour specs contain zero-padding, this should not be removed in the data for this command.

Complex Display Commands

Command	Details		Min version
50	Set pixel		1.1
	Data in: 1 byte: co-ordinate, 1 colour spec	Data out: None
	Should only be used very rarely, as it's data-inefficient. Sets the pixel at (x, y) to the given colour. The low nybble of the co-ordinate is ignored.
51	Draw line		1.1
	Data in: 1 byte: co-ordinate, 1 colour spec	Data out: None
	Draws a 1-pixel-width line in the given colour from absolute co-ordinates (x, y) to absolute co-ordinates (w, h) using Bresenham's algorithm.
52	Draw hollow rectangle		1.1
	Data in: 1 byte: co-ordinate, 1 colour spec	Data out: None
	Draws a hollow rectangle in the given colour, with top-left corner at (x, y) and bottom right corner at (w, h).
53	Draw filled rectangle		1.1
	Data in: 1 byte: co-ordinate, 1 colour spec	Data out: None
	Draws a filled rectangle in the given colour, with top-left corner at (x, y) and bottom right corner at (w, h).
54	Scroll module		1.1
	Data in: 1 byte: scroll spec	Data out: None
	Scrolls the image on the module according to the given spec. Pixels scrolled off the edge do not wrap, and new pixels will be black.
55	Scroll rectangle		1.1
	Data in: 2 bytes: co-ordinate (1), scroll spec (1)	Data out: None
	Scrolls the image within the rectangle from (x, y) to (w, h) according to the given spec. Pixels scrolled off the edge do not wrap, and new pixels will be black.
56	Scroll module with data		1.2
	Data in: 1 byte: scroll spec, 4-16 colour specs	Data out: 4-16 colour specs
	Scrolls the image on the module according to the given spec. Pixels scrolled off the edge do not wrap but will be returned in increasing X/Y co-ordinates, and new pixels will be taken from the colour specs given, in increasing X/Y co-ordinates.
57	Scroll rectangle with data		1.2
	Data in: 2 bytes: co-ordinate (1), scroll spec (1); 1-16 colour specs	Data out: 1-16 colour specs
	Scrolls the image within the rectangle from (x, y) to (w, h) according to the given spec. Pixels scrolled off the edge do not wrap but will be returned in increasing X/Y co-ordinates, and new pixels will be taken from the colour specs given, in increasing X/Y co-ordinates.
5E	Draw single-colour pattern		1.1
	Data in: 2 bytes: pattern, 1 colour spec	Data out: None
	The first two bytes define the pattern to be drawn, with the set bits corresponding to a pixel being set to the given colour. The bits are ordered in the usual way, so the highest bit of the pair is (0,0), the highest of the second byte is (0,2), and the lowest of the pair is (3, 3).
5F	Draw pattern rect		1.1
	Data in: 1 byte: co-ordinate, 1-16 colour specs	Data out: None
	The co-ordinate byte defines a rectangle from (x, y) to (w, h), which is filled with the colour specs in the usual ordering.