LED_for_hackspace - LED screen driver build for hackspace.

Users » madcowswe » Code » LED_for_hackspace

Oskar Weigl / Mbed 2 deprecated LED_for_hackspace

LED screen driver build for hackspace.

ledScreen.h@0:f16a1d69a386, 2012-02-29 (annotated)

Committer:: madcowswe
Date:: Wed Feb 29 17:01:43 2012 +0000
Revision:: 0:f16a1d69a386
Child:: 1:1af5060b2a34

Who changed what in which revision?

User	Revision	Line number	New contents of line
madcowswe	0:f16a1d69a386	1	#include "mbed.h"
madcowswe	0:f16a1d69a386	2
madcowswe	0:f16a1d69a386	3	/*
madcowswe	0:f16a1d69a386	4	******************************************************
madcowswe	0:f16a1d69a386	5	Hacked together by Imperial College Robotics Society
madcowswe	0:f16a1d69a386	6	******************************************************
madcowswe	0:f16a1d69a386	7
madcowswe	0:f16a1d69a386	8	Usage:
madcowswe	0:f16a1d69a386	9	Example code supplied (main.cpp). Format of data input: 8bit RGB channels per pixel sequential in one framebuffer.
madcowswe	0:f16a1d69a386	10
madcowswe	0:f16a1d69a386	11	Note:
madcowswe	0:f16a1d69a386	12	This version uses inverted outputs (to bring voltage from 3.3 to 5v and drive more current) for data, clock and address lines.
madcowswe	0:f16a1d69a386	13
madcowswe	0:f16a1d69a386	14	Quirks of current platform:
madcowswe	0:f16a1d69a386	15	address lines are put through inverters, code still thinks it's addressing with logic 1's,
madcowswe	0:f16a1d69a386	16	whereas in reality MA0 is inverted and put into the ribbon cable line of MA1 and vice-versa
madcowswe	0:f16a1d69a386	17
madcowswe	0:f16a1d69a386	18	*/
madcowswe	0:f16a1d69a386	19
madcowswe	0:f16a1d69a386	20	extern "C" void frameout(unsigned char dsVal[], unsigned char transformedSource[]);
madcowswe	0:f16a1d69a386	21
madcowswe	0:f16a1d69a386	22	class ledScreen {
madcowswe	0:f16a1d69a386	23	public:
madcowswe	0:f16a1d69a386	24	ledScreen();
madcowswe	0:f16a1d69a386	25	~ledScreen() {}
madcowswe	0:f16a1d69a386	26
madcowswe	0:f16a1d69a386	27	void transformFrame(unsigned char* imageSource);
madcowswe	0:f16a1d69a386	28	void transformFrame2(unsigned char* imageSource);
madcowswe	0:f16a1d69a386	29	void outputFrame();
madcowswe	0:f16a1d69a386	30	void start(); // start outputting frames on an interrupt
madcowswe	0:f16a1d69a386	31
madcowswe	0:f16a1d69a386	32	private:
madcowswe	0:f16a1d69a386	33
madcowswe	0:f16a1d69a386	34	int MAX_PULSE_WIDTH; // constant: max enable pulse duration
madcowswe	0:f16a1d69a386	35	int pulseLength; // length of current pulse (used in delta-sigma pwm)
madcowswe	0:f16a1d69a386	36	int OP_TIME;
madcowswe	0:f16a1d69a386	37
madcowswe	0:f16a1d69a386	38	static const int NUM_PANELS = 3; // number of panels horizontally
madcowswe	0:f16a1d69a386	39
madcowswe	0:f16a1d69a386	40	int running;
madcowswe	0:f16a1d69a386	41	int subFrameCtr;
madcowswe	0:f16a1d69a386	42
madcowswe	0:f16a1d69a386	43	Timeout nextFrameTimer; // timeout routine
madcowswe	0:f16a1d69a386	44
madcowswe	0:f16a1d69a386	45	// Buffers to hold the RGB data after rearranging to match the LED shifting pattern
madcowswe	0:f16a1d69a386	46	unsigned char transformedSource[2563NUM_PANELS];
madcowswe	0:f16a1d69a386	47
madcowswe	0:f16a1d69a386	48	// Error values for all 256 brightness levels
madcowswe	0:f16a1d69a386	49	unsigned int dsErr[256];
madcowswe	0:f16a1d69a386	50	unsigned int ssdsErr[256];
madcowswe	0:f16a1d69a386	51
madcowswe	0:f16a1d69a386	52	// On/off state per sub-frame for all 256 brightness levels
madcowswe	0:f16a1d69a386	53	unsigned char dsVal[256];
madcowswe	0:f16a1d69a386	54
madcowswe	0:f16a1d69a386	55	// Precomputed gamma for all 256 brightness levels
madcowswe	0:f16a1d69a386	56	unsigned short gamma[256];
madcowswe	0:f16a1d69a386	57
madcowswe	0:f16a1d69a386	58
madcowswe	0:f16a1d69a386	59	DigitalOut flatch; // data latch (for all connected panels in parallel)
madcowswe	0:f16a1d69a386	60	DigitalOut MA0; // module address 0
madcowswe	0:f16a1d69a386	61	DigitalOut MA1;
madcowswe	0:f16a1d69a386	62	DigitalOut NREN; // active low enable for red channel (low -> LED on). Note: need to have enable high when latching data
madcowswe	0:f16a1d69a386	63	DigitalOut Rdat; // red data
madcowswe	0:f16a1d69a386	64	DigitalOut Gdat; // green data
madcowswe	0:f16a1d69a386	65	DigitalOut Bdat; // blue data
madcowswe	0:f16a1d69a386	66	DigitalOut sclk; // clock
madcowswe	0:f16a1d69a386	67
madcowswe	0:f16a1d69a386	68	};
madcowswe	0:f16a1d69a386	69
madcowswe	0:f16a1d69a386	70	ledScreen::ledScreen() :
madcowswe	0:f16a1d69a386	71	flatch(p11), // data latch (for all connected panels in parallel)
madcowswe	0:f16a1d69a386	72	MA0(p18), // module address 0
madcowswe	0:f16a1d69a386	73	MA1(p19),
madcowswe	0:f16a1d69a386	74	NREN(p12), // active low enable for red channel (low -> LED on). Note: need to have enable high when latching data
madcowswe	0:f16a1d69a386	75	Rdat(p15), // red data
madcowswe	0:f16a1d69a386	76	Gdat(p16), // green data
madcowswe	0:f16a1d69a386	77	Bdat(p17), // blue data
madcowswe	0:f16a1d69a386	78	sclk(p14) { // clock
madcowswe	0:f16a1d69a386	79
madcowswe	0:f16a1d69a386	80	// precompute gamma for every possible RGB intensity value (0-255).
madcowswe	0:f16a1d69a386	81	// Gamma correction with gamma = 3, downshifting by 8 to bring the range of values back to 0-65535
madcowswe	0:f16a1d69a386	82	for (int i=0; i<256; i++) {
madcowswe	0:f16a1d69a386	83	gamma[i] = pow(i, 2.2) * 0.33;//(iii)>>8;
madcowswe	0:f16a1d69a386	84	}
madcowswe	0:f16a1d69a386	85
madcowswe	0:f16a1d69a386	86	// initialising lines
madcowswe	0:f16a1d69a386	87	flatch = 0;
madcowswe	0:f16a1d69a386	88	NREN = 0;
madcowswe	0:f16a1d69a386	89	sclk = 0;
madcowswe	0:f16a1d69a386	90
madcowswe	0:f16a1d69a386	91	// initialising values
madcowswe	0:f16a1d69a386	92	MAX_PULSE_WIDTH = 512; //must currently be a power of 2, and when changing this, you must change the ssdsErr crossover masking
madcowswe	0:f16a1d69a386	93	pulseLength = MAX_PULSE_WIDTH;
madcowswe	0:f16a1d69a386	94	OP_TIME = 345; //Determined by scoping. Change this every time you change num screens
madcowswe	0:f16a1d69a386	95	//NUM_PANELS = 3
madcowswe	0:f16a1d69a386	96
madcowswe	0:f16a1d69a386	97	running=0;
madcowswe	0:f16a1d69a386	98	subFrameCtr=0;
madcowswe	0:f16a1d69a386	99
madcowswe	0:f16a1d69a386	100	// initialising errors for delta-sigma
madcowswe	0:f16a1d69a386	101	for (int j=0; j<256; j++) {
madcowswe	0:f16a1d69a386	102	dsErr[j] = 0;
madcowswe	0:f16a1d69a386	103	ssdsErr[j] = 0;
madcowswe	0:f16a1d69a386	104	}
madcowswe	0:f16a1d69a386	105
madcowswe	0:f16a1d69a386	106	}
madcowswe	0:f16a1d69a386	107
madcowswe	0:f16a1d69a386	108	void ledScreen::start() {
madcowswe	0:f16a1d69a386	109	running=1;
madcowswe	0:f16a1d69a386	110	outputFrame();
madcowswe	0:f16a1d69a386	111	}
madcowswe	0:f16a1d69a386	112
madcowswe	0:f16a1d69a386	113
madcowswe	0:f16a1d69a386	114	void ledScreen::transformFrame2(unsigned char* imageSource) {
madcowswe	0:f16a1d69a386	115
madcowswe	0:f16a1d69a386	116	int psp = 0; // panel space pointer
madcowswe	0:f16a1d69a386	117	int tpsp = 0; // target psp
madcowswe	0:f16a1d69a386	118	int isp = 8 * 3; // imag espace pointer
madcowswe	0:f16a1d69a386	119	// preprocessing the image data to match shifting pattern
madcowswe	0:f16a1d69a386	120	for (int panel = 0; panel < NUM_PANELS; panel++) {
madcowswe	0:f16a1d69a386	121	// int base = panel * 0x20; //i - image space*/
madcowswe	0:f16a1d69a386	122
madcowswe	0:f16a1d69a386	123	for (int drows = 0; drows < 8; drows++) {
madcowswe	0:f16a1d69a386	124	//for (int m = 0; m < 0x1F; m++) { //m - quad block in panel space
madcowswe	0:f16a1d69a386	125
madcowswe	0:f16a1d69a386	126	for (tpsp = psp + (8*3); psp < tpsp;) { //0th quad
madcowswe	0:f16a1d69a386	127	isp -= 3;
madcowswe	0:f16a1d69a386	128	transformedSource[psp++] = imageSource[isp];
madcowswe	0:f16a1d69a386	129	transformedSource[psp++] = imageSource[isp+1];
madcowswe	0:f16a1d69a386	130	transformedSource[psp++] = imageSource[isp+2];
madcowswe	0:f16a1d69a386	131	}
madcowswe	0:f16a1d69a386	132
madcowswe	0:f16a1d69a386	133	//next row
madcowswe	0:f16a1d69a386	134	isp += 0x10 * NUM_PANELS * 3;
madcowswe	0:f16a1d69a386	135	for (tpsp = psp + (8*3); psp < tpsp; isp+=3) { //2nd quad
madcowswe	0:f16a1d69a386	136	transformedSource[psp++] = imageSource[isp];
madcowswe	0:f16a1d69a386	137	transformedSource[psp++] = imageSource[isp+1];
madcowswe	0:f16a1d69a386	138	transformedSource[psp++] = imageSource[isp+2];
madcowswe	0:f16a1d69a386	139	}
madcowswe	0:f16a1d69a386	140
madcowswe	0:f16a1d69a386	141	//previous row
madcowswe	0:f16a1d69a386	142	isp -= (0x10 * NUM_PANELS - 8) * 3;
madcowswe	0:f16a1d69a386	143	for (tpsp = psp + (8*3); psp < tpsp;) { //1st quad
madcowswe	0:f16a1d69a386	144	isp-=3;
madcowswe	0:f16a1d69a386	145	transformedSource[psp++] = imageSource[isp];
madcowswe	0:f16a1d69a386	146	transformedSource[psp++] = imageSource[isp+1];
madcowswe	0:f16a1d69a386	147	transformedSource[psp++] = imageSource[isp+2];
madcowswe	0:f16a1d69a386	148	}
madcowswe	0:f16a1d69a386	149	isp += 0x10 * NUM_PANELS * 3;
madcowswe	0:f16a1d69a386	150	for (tpsp = psp + (8*3); psp < tpsp; isp+=3) { //3rd quad
madcowswe	0:f16a1d69a386	151	transformedSource[psp++] = imageSource[isp];
madcowswe	0:f16a1d69a386	152	transformedSource[psp++] = imageSource[isp+1];
madcowswe	0:f16a1d69a386	153	transformedSource[psp++] = imageSource[isp+2];
madcowswe	0:f16a1d69a386	154
madcowswe	0:f16a1d69a386	155	}
madcowswe	0:f16a1d69a386	156	isp += (0x10 * NUM_PANELS - 8) * 3;
madcowswe	0:f16a1d69a386	157	}
madcowswe	0:f16a1d69a386	158
madcowswe	0:f16a1d69a386	159	isp += (0x10 - 0x20 * NUM_PANELS * 8) * 3;
madcowswe	0:f16a1d69a386	160	}
madcowswe	0:f16a1d69a386	161	}
madcowswe	0:f16a1d69a386	162
madcowswe	0:f16a1d69a386	163	void ledScreen::transformFrame(unsigned char* imageSource) {
madcowswe	0:f16a1d69a386	164	unsigned char rotatedSource[2563NUM_PANELS];
madcowswe	0:f16a1d69a386	165
madcowswe	0:f16a1d69a386	166	for (int panels = 0; panels < 3; panels++){
madcowswe	0:f16a1d69a386	167	for (int x = 0; x<16; x++){
madcowswe	0:f16a1d69a386	168	for (int y = 0; y<16; y++){
madcowswe	0:f16a1d69a386	169	for (int c = 0; c < 3; c++){
madcowswe	0:f16a1d69a386	170	rotatedSource[((15-x) + panels16 + 48y)3 + c] = imageSource[(y + panels16 + 48x)3 + c];
madcowswe	0:f16a1d69a386	171	}
madcowswe	0:f16a1d69a386	172	}
madcowswe	0:f16a1d69a386	173	}
madcowswe	0:f16a1d69a386	174	}
madcowswe	0:f16a1d69a386	175
madcowswe	0:f16a1d69a386	176	transformFrame2(rotatedSource);
madcowswe	0:f16a1d69a386	177	}
madcowswe	0:f16a1d69a386	178
madcowswe	0:f16a1d69a386	179	// Output one frame and call itself after a period of time if running is set to true
madcowswe	0:f16a1d69a386	180	void ledScreen::outputFrame() {
madcowswe	0:f16a1d69a386	181
madcowswe	0:f16a1d69a386	182	if (pulseLength != MAX_PULSE_WIDTH)
madcowswe	0:f16a1d69a386	183	NREN = 1; // turn off
madcowswe	0:f16a1d69a386	184
madcowswe	0:f16a1d69a386	185	if (subFrameCtr<=0) subFrameCtr=36;
madcowswe	0:f16a1d69a386	186	subFrameCtr--;
madcowswe	0:f16a1d69a386	187
madcowswe	0:f16a1d69a386	188	if (subFrameCtr == 0) { // Every cycle of delta sigma we take a snapshot of the error that needs to be corrected by the short pulses.
madcowswe	0:f16a1d69a386	189	for (int i = 0; i < 256; i++) { // This is required to eliminate visible flicker due to beat frequencies otherwise created.
madcowswe	0:f16a1d69a386	190	dsErr[i] += ssdsErr[i] & 0xFE000000;
madcowswe	0:f16a1d69a386	191	ssdsErr[i] %= 0x10000;
madcowswe	0:f16a1d69a386	192	ssdsErr[i] += dsErr[i] % (512 * 0x10000);
madcowswe	0:f16a1d69a386	193	dsErr[i] &= 0xFE000000;
madcowswe	0:f16a1d69a386	194	}
madcowswe	0:f16a1d69a386	195
madcowswe	0:f16a1d69a386	196	// Doing delta sigma for the snapshot
madcowswe	0:f16a1d69a386	197	for (int i = 0; i <= 9; i++) {
madcowswe	0:f16a1d69a386	198	int lpl = 1<<i;
madcowswe	0:f16a1d69a386	199
madcowswe	0:f16a1d69a386	200	if (ssdsErr[i]/0x10000 & lpl)
madcowswe	0:f16a1d69a386	201	ssdsErr[i]-=(0x10000-gamma[i])*lpl;
madcowswe	0:f16a1d69a386	202	else
madcowswe	0:f16a1d69a386	203	ssdsErr[i]+=gamma[i]*lpl;
madcowswe	0:f16a1d69a386	204	}
madcowswe	0:f16a1d69a386	205
madcowswe	0:f16a1d69a386	206	}
madcowswe	0:f16a1d69a386	207
madcowswe	0:f16a1d69a386	208	// produce pulse lengths of 1, 2, 4, ... 256, spread throughout all subframes (only one in four are not MAX_PULSE_WIDTH long)
madcowswe	0:f16a1d69a386	209	pulseLength = ((subFrameCtr%4)?MAX_PULSE_WIDTH:(1<<(subFrameCtr>>2)));
madcowswe	0:f16a1d69a386	210
madcowswe	0:f16a1d69a386	211	for (int i = 0; i < 256; i++) {
madcowswe	0:f16a1d69a386	212	if (pulseLength == MAX_PULSE_WIDTH) {
madcowswe	0:f16a1d69a386	213	// Delta-Sigma modulation with variable pulse length weighting
madcowswe	0:f16a1d69a386	214	// Based on energy dimensions (time * amplitude)
madcowswe	0:f16a1d69a386	215	if (dsErr[i] > (0x10000-gamma[i])*pulseLength) {
madcowswe	0:f16a1d69a386	216	dsVal[i] = 0;//-1; Invert as we are using inverting buffers
madcowswe	0:f16a1d69a386	217	dsErr[i]-=(0x10000-gamma[i])*pulseLength;
madcowswe	0:f16a1d69a386	218	} else {
madcowswe	0:f16a1d69a386	219	dsVal[i] = (unsigned char)-1;
madcowswe	0:f16a1d69a386	220	dsErr[i]+=gamma[i]*pulseLength;
madcowswe	0:f16a1d69a386	221	}
madcowswe	0:f16a1d69a386	222	} else { // if short pulse
madcowswe	0:f16a1d69a386	223	if (ssdsErr[i]/0x10000 & pulseLength) {
madcowswe	0:f16a1d69a386	224	//Doing proper least significant delta sigma live still causes flicker (but only for dim pixels)
madcowswe	0:f16a1d69a386	225	//ssdsErr[i]-=(0x10000-gamma[i])*pulseLength;
madcowswe	0:f16a1d69a386	226	dsVal[i] = 0;
madcowswe	0:f16a1d69a386	227	} else {
madcowswe	0:f16a1d69a386	228	dsVal[i] = (unsigned char)-1;
madcowswe	0:f16a1d69a386	229	//ssdsErr[i]+=gamma[i]*pulseLength;
madcowswe	0:f16a1d69a386	230	}
madcowswe	0:f16a1d69a386	231
madcowswe	0:f16a1d69a386	232	}
madcowswe	0:f16a1d69a386	233	}
madcowswe	0:f16a1d69a386	234
madcowswe	0:f16a1d69a386	235	// output data
madcowswe	0:f16a1d69a386	236	for (int i = 0; i < NUM_PANELS; i++) { // NUM_PANELS
madcowswe	0:f16a1d69a386	237	MA0 = i&1;
madcowswe	0:f16a1d69a386	238	MA1 = i&2;
madcowswe	0:f16a1d69a386	239
madcowswe	0:f16a1d69a386	240	frameout(dsVal, &transformedSource[i2563]);
madcowswe	0:f16a1d69a386	241	}
madcowswe	0:f16a1d69a386	242
madcowswe	0:f16a1d69a386	243	NREN = 1; // need to have enables high before every latch, (in case we are on a long pulse)
madcowswe	0:f16a1d69a386	244	flatch = 1; // latching all data to LEDs
madcowswe	0:f16a1d69a386	245	flatch = 0;
madcowswe	0:f16a1d69a386	246	NREN = 0; // turn on LEDs
madcowswe	0:f16a1d69a386	247
madcowswe	0:f16a1d69a386	248	if (pulseLength < 4) { // short pulses done through wait
madcowswe	0:f16a1d69a386	249	wait_us(pulseLength);
madcowswe	0:f16a1d69a386	250	NREN = 1; //Turn off LEDs
madcowswe	0:f16a1d69a386	251
madcowswe	0:f16a1d69a386	252	bool wasrunning = running;
madcowswe	0:f16a1d69a386	253	running = false;
madcowswe	0:f16a1d69a386	254	outputFrame(); //this will recurse only once due to the distrubution of pulses. pulseLength of the next instance will be attached.
madcowswe	0:f16a1d69a386	255	running = wasrunning;
madcowswe	0:f16a1d69a386	256	}
madcowswe	0:f16a1d69a386	257	// long waits done through attaching an interrupt that will turn off the LEDs at the start of next function call.
madcowswe	0:f16a1d69a386	258	// Meanwhile, the main code can run between the interrupts.
madcowswe	0:f16a1d69a386	259	if (running) nextFrameTimer.attach_us(this, &ledScreen::outputFrame, (pulseLength == MAX_PULSE_WIDTH) ? pulseLength - OP_TIME : pulseLength);
madcowswe	0:f16a1d69a386	260	}

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	29 Feb 2012
Imports:	4
Forks:	0
Commits:	2
Dependents:	0
Dependencies:	1
Followers:	2

ledScreen.h@0:f16a1d69a386, 2012-02-29 (annotated)

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