Mercurial > code > home > repos > light9

comparison rgbled/Adafruit_NeoPixel/Adafruit_NeoPixel.cpp @ 1231:ef4ae15f2661

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
copy in rgb led program for arduino Ignore-this: ee63cf3e2100597625a4392bd95aba0d
author Drew Perttula <drewp@bigasterisk.com>
date Wed, 10 Jun 2015 04:55:39 +0000
parents
children
comparison
equal deleted inserted replaced
1230:23377f8efd09 1231:ef4ae15f2661
1 /*-------------------------------------------------------------------------
2 Arduino library to control a wide variety of WS2811- and WS2812-based RGB
3 LED devices such as Adafruit FLORA RGB Smart Pixels and NeoPixel strips.
4 Currently handles 400 and 800 KHz bitstreams on 8, 12 and 16 MHz ATmega
5 MCUs, with LEDs wired for RGB or GRB color order. 8 MHz MCUs provide
6 output on PORTB and PORTD, while 16 MHz chips can handle most output pins
7 (possible exception with upper PORT registers on the Arduino Mega).
8
9 Written by Phil Burgess / Paint Your Dragon for Adafruit Industries,
10 contributions by PJRC and other members of the open source community.
11
12 Adafruit invests time and resources providing this open source code,
13 please support Adafruit and open-source hardware by purchasing products
14 from Adafruit!
15
16 -------------------------------------------------------------------------
17 This file is part of the Adafruit NeoPixel library.
18
19 NeoPixel is free software: you can redistribute it and/or modify
20 it under the terms of the GNU Lesser General Public License as
21 published by the Free Software Foundation, either version 3 of
22 the License, or (at your option) any later version.
23
24 NeoPixel is distributed in the hope that it will be useful,
25 but WITHOUT ANY WARRANTY; without even the implied warranty of
26 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
27 GNU Lesser General Public License for more details.
28
29 You should have received a copy of the GNU Lesser General Public
30 License along with NeoPixel. If not, see
31 <http://www.gnu.org/licenses/>.
32 -------------------------------------------------------------------------*/
33
34 #include "Adafruit_NeoPixel.h"
35
36 Adafruit_NeoPixel::Adafruit_NeoPixel(uint16_t n, uint8_t p, uint8_t t) :
37 numLEDs(n), numBytes(n * 3), pin(p), brightness(0),
38 pixels(NULL), type(t), endTime(0)
39 #ifdef __AVR__
40 ,port(portOutputRegister(digitalPinToPort(p))),
41 pinMask(digitalPinToBitMask(p))
42 #endif
43 {
44 if((pixels = (uint8_t *)malloc(numBytes))) {
45 memset(pixels, 0, numBytes);
46 }
47 if(t & NEO_GRB) { // GRB vs RGB; might add others if needed
48 rOffset = 1;
49 gOffset = 0;
50 bOffset = 2;
51 } else if (t & NEO_BRG) {
52 rOffset = 1;
53 gOffset = 2;
54 bOffset = 0;
55 } else {
56 rOffset = 0;
57 gOffset = 1;
58 bOffset = 2;
59 }
60
61 }
62
63 Adafruit_NeoPixel::~Adafruit_NeoPixel() {
64 if(pixels) free(pixels);
65 pinMode(pin, INPUT);
66 }
67
68 void Adafruit_NeoPixel::begin(void) {
69 pinMode(pin, OUTPUT);
70 digitalWrite(pin, LOW);
71 }
72
73 void Adafruit_NeoPixel::show(void) {
74
75 if(!pixels) return;
76
77 // Data latch = 50+ microsecond pause in the output stream. Rather than
78 // put a delay at the end of the function, the ending time is noted and
79 // the function will simply hold off (if needed) on issuing the
80 // subsequent round of data until the latch time has elapsed. This
81 // allows the mainline code to start generating the next frame of data
82 // rather than stalling for the latch.
83 while(!canShow());
84 // endTime is a private member (rather than global var) so that mutliple
85 // instances on different pins can be quickly issued in succession (each
86 // instance doesn't delay the next).
87
88 // In order to make this code runtime-configurable to work with any pin,
89 // SBI/CBI instructions are eschewed in favor of full PORT writes via the
90 // OUT or ST instructions. It relies on two facts: that peripheral
91 // functions (such as PWM) take precedence on output pins, so our PORT-
92 // wide writes won't interfere, and that interrupts are globally disabled
93 // while data is being issued to the LEDs, so no other code will be
94 // accessing the PORT. The code takes an initial 'snapshot' of the PORT
95 // state, computes 'pin high' and 'pin low' values, and writes these back
96 // to the PORT register as needed.
97
98 noInterrupts(); // Need 100% focus on instruction timing
99
100 #ifdef __AVR__
101
102 volatile uint16_t
103 i = numBytes; // Loop counter
104 volatile uint8_t
105 *ptr = pixels, // Pointer to next byte
106 b = *ptr++, // Current byte value
107 hi, // PORT w/output bit set high
108 lo; // PORT w/output bit set low
109
110 // Hand-tuned assembly code issues data to the LED drivers at a specific
111 // rate. There's separate code for different CPU speeds (8, 12, 16 MHz)
112 // for both the WS2811 (400 KHz) and WS2812 (800 KHz) drivers. The
113 // datastream timing for the LED drivers allows a little wiggle room each
114 // way (listed in the datasheets), so the conditions for compiling each
115 // case are set up for a range of frequencies rather than just the exact
116 // 8, 12 or 16 MHz values, permitting use with some close-but-not-spot-on
117 // devices (e.g. 16.5 MHz DigiSpark). The ranges were arrived at based
118 // on the datasheet figures and have not been extensively tested outside
119 // the canonical 8/12/16 MHz speeds; there's no guarantee these will work
120 // close to the extremes (or possibly they could be pushed further).
121 // Keep in mind only one CPU speed case actually gets compiled; the
122 // resulting program isn't as massive as it might look from source here.
123
124 // 8 MHz(ish) AVR ---------------------------------------------------------
125 #if (F_CPU >= 7400000UL) && (F_CPU <= 9500000UL)
126
127 #ifdef NEO_KHZ400
128 if((type & NEO_SPDMASK) == NEO_KHZ800) { // 800 KHz bitstream
129 #endif
130
131 volatile uint8_t n1, n2 = 0; // First, next bits out
132
133 // Squeezing an 800 KHz stream out of an 8 MHz chip requires code
134 // specific to each PORT register. At present this is only written
135 // to work with pins on PORTD or PORTB, the most likely use case --
136 // this covers all the pins on the Adafruit Flora and the bulk of
137 // digital pins on the Arduino Pro 8 MHz (keep in mind, this code
138 // doesn't even get compiled for 16 MHz boards like the Uno, Mega,
139 // Leonardo, etc., so don't bother extending this out of hand).
140 // Additional PORTs could be added if you really need them, just
141 // duplicate the else and loop and change the PORT. Each add'l
142 // PORT will require about 150(ish) bytes of program space.
143
144 // 10 instruction clocks per bit: HHxxxxxLLL
145 // OUT instructions: ^ ^ ^ (T=0,2,7)
146
147 #ifdef PORTD // PORTD isn't present on ATtiny85, etc.
148
149 if(port == &PORTD) {
150
151 hi = PORTD | pinMask;
152 lo = PORTD & ~pinMask;
153 n1 = lo;
154 if(b & 0x80) n1 = hi;
155
156 // Dirty trick: RJMPs proceeding to the next instruction are used
157 // to delay two clock cycles in one instruction word (rather than
158 // using two NOPs). This was necessary in order to squeeze the
159 // loop down to exactly 64 words -- the maximum possible for a
160 // relative branch.
161
162 asm volatile(
163 "headD:" "\n\t" // Clk Pseudocode
164 // Bit 7:
165 "out %[port] , %[hi]" "\n\t" // 1 PORT = hi
166 "mov %[n2] , %[lo]" "\n\t" // 1 n2 = lo
167 "out %[port] , %[n1]" "\n\t" // 1 PORT = n1
168 "rjmp .+0" "\n\t" // 2 nop nop
169 "sbrc %[byte] , 6" "\n\t" // 1-2 if(b & 0x40)
170 "mov %[n2] , %[hi]" "\n\t" // 0-1 n2 = hi
171 "out %[port] , %[lo]" "\n\t" // 1 PORT = lo
172 "rjmp .+0" "\n\t" // 2 nop nop
173 // Bit 6:
174 "out %[port] , %[hi]" "\n\t" // 1 PORT = hi
175 "mov %[n1] , %[lo]" "\n\t" // 1 n1 = lo
176 "out %[port] , %[n2]" "\n\t" // 1 PORT = n2
177 "rjmp .+0" "\n\t" // 2 nop nop
178 "sbrc %[byte] , 5" "\n\t" // 1-2 if(b & 0x20)
179 "mov %[n1] , %[hi]" "\n\t" // 0-1 n1 = hi
180 "out %[port] , %[lo]" "\n\t" // 1 PORT = lo
181 "rjmp .+0" "\n\t" // 2 nop nop
182 // Bit 5:
183 "out %[port] , %[hi]" "\n\t" // 1 PORT = hi
184 "mov %[n2] , %[lo]" "\n\t" // 1 n2 = lo
185 "out %[port] , %[n1]" "\n\t" // 1 PORT = n1
186 "rjmp .+0" "\n\t" // 2 nop nop
187 "sbrc %[byte] , 4" "\n\t" // 1-2 if(b & 0x10)
188 "mov %[n2] , %[hi]" "\n\t" // 0-1 n2 = hi
189 "out %[port] , %[lo]" "\n\t" // 1 PORT = lo
190 "rjmp .+0" "\n\t" // 2 nop nop
191 // Bit 4:
192 "out %[port] , %[hi]" "\n\t" // 1 PORT = hi
193 "mov %[n1] , %[lo]" "\n\t" // 1 n1 = lo
194 "out %[port] , %[n2]" "\n\t" // 1 PORT = n2
195 "rjmp .+0" "\n\t" // 2 nop nop
196 "sbrc %[byte] , 3" "\n\t" // 1-2 if(b & 0x08)
197 "mov %[n1] , %[hi]" "\n\t" // 0-1 n1 = hi
198 "out %[port] , %[lo]" "\n\t" // 1 PORT = lo
199 "rjmp .+0" "\n\t" // 2 nop nop
200 // Bit 3:
201 "out %[port] , %[hi]" "\n\t" // 1 PORT = hi
202 "mov %[n2] , %[lo]" "\n\t" // 1 n2 = lo
203 "out %[port] , %[n1]" "\n\t" // 1 PORT = n1
204 "rjmp .+0" "\n\t" // 2 nop nop
205 "sbrc %[byte] , 2" "\n\t" // 1-2 if(b & 0x04)
206 "mov %[n2] , %[hi]" "\n\t" // 0-1 n2 = hi
207 "out %[port] , %[lo]" "\n\t" // 1 PORT = lo
208 "rjmp .+0" "\n\t" // 2 nop nop
209 // Bit 2:
210 "out %[port] , %[hi]" "\n\t" // 1 PORT = hi
211 "mov %[n1] , %[lo]" "\n\t" // 1 n1 = lo
212 "out %[port] , %[n2]" "\n\t" // 1 PORT = n2
213 "rjmp .+0" "\n\t" // 2 nop nop
214 "sbrc %[byte] , 1" "\n\t" // 1-2 if(b & 0x02)
215 "mov %[n1] , %[hi]" "\n\t" // 0-1 n1 = hi
216 "out %[port] , %[lo]" "\n\t" // 1 PORT = lo
217 "rjmp .+0" "\n\t" // 2 nop nop
218 // Bit 1:
219 "out %[port] , %[hi]" "\n\t" // 1 PORT = hi
220 "mov %[n2] , %[lo]" "\n\t" // 1 n2 = lo
221 "out %[port] , %[n1]" "\n\t" // 1 PORT = n1
222 "rjmp .+0" "\n\t" // 2 nop nop
223 "sbrc %[byte] , 0" "\n\t" // 1-2 if(b & 0x01)
224 "mov %[n2] , %[hi]" "\n\t" // 0-1 n2 = hi
225 "out %[port] , %[lo]" "\n\t" // 1 PORT = lo
226 "sbiw %[count], 1" "\n\t" // 2 i-- (don't act on Z flag yet)
227 // Bit 0:
228 "out %[port] , %[hi]" "\n\t" // 1 PORT = hi
229 "mov %[n1] , %[lo]" "\n\t" // 1 n1 = lo
230 "out %[port] , %[n2]" "\n\t" // 1 PORT = n2
231 "ld %[byte] , %a[ptr]+" "\n\t" // 2 b = *ptr++
232 "sbrc %[byte] , 7" "\n\t" // 1-2 if(b & 0x80)
233 "mov %[n1] , %[hi]" "\n\t" // 0-1 n1 = hi
234 "out %[port] , %[lo]" "\n\t" // 1 PORT = lo
235 "brne headD" "\n" // 2 while(i) (Z flag set above)
236 : [byte] "+r" (b),
237 [n1] "+r" (n1),
238 [n2] "+r" (n2),
239 [count] "+w" (i)
240 : [port] "I" (_SFR_IO_ADDR(PORTD)),
241 [ptr] "e" (ptr),
242 [hi] "r" (hi),
243 [lo] "r" (lo));
244
245 } else if(port == &PORTB) {
246
247 #endif // PORTD
248
249 // Same as above, just switched to PORTB and stripped of comments.
250 hi = PORTB | pinMask;
251 lo = PORTB & ~pinMask;
252 n1 = lo;
253 if(b & 0x80) n1 = hi;
254
255 asm volatile(
256 "headB:" "\n\t"
257 "out %[port] , %[hi]" "\n\t"
258 "mov %[n2] , %[lo]" "\n\t"
259 "out %[port] , %[n1]" "\n\t"
260 "rjmp .+0" "\n\t"
261 "sbrc %[byte] , 6" "\n\t"
262 "mov %[n2] , %[hi]" "\n\t"
263 "out %[port] , %[lo]" "\n\t"
264 "rjmp .+0" "\n\t"
265 "out %[port] , %[hi]" "\n\t"
266 "mov %[n1] , %[lo]" "\n\t"
267 "out %[port] , %[n2]" "\n\t"
268 "rjmp .+0" "\n\t"
269 "sbrc %[byte] , 5" "\n\t"
270 "mov %[n1] , %[hi]" "\n\t"
271 "out %[port] , %[lo]" "\n\t"
272 "rjmp .+0" "\n\t"
273 "out %[port] , %[hi]" "\n\t"
274 "mov %[n2] , %[lo]" "\n\t"
275 "out %[port] , %[n1]" "\n\t"
276 "rjmp .+0" "\n\t"
277 "sbrc %[byte] , 4" "\n\t"
278 "mov %[n2] , %[hi]" "\n\t"
279 "out %[port] , %[lo]" "\n\t"
280 "rjmp .+0" "\n\t"
281 "out %[port] , %[hi]" "\n\t"
282 "mov %[n1] , %[lo]" "\n\t"
283 "out %[port] , %[n2]" "\n\t"
284 "rjmp .+0" "\n\t"
285 "sbrc %[byte] , 3" "\n\t"
286 "mov %[n1] , %[hi]" "\n\t"
287 "out %[port] , %[lo]" "\n\t"
288 "rjmp .+0" "\n\t"
289 "out %[port] , %[hi]" "\n\t"
290 "mov %[n2] , %[lo]" "\n\t"
291 "out %[port] , %[n1]" "\n\t"
292 "rjmp .+0" "\n\t"
293 "sbrc %[byte] , 2" "\n\t"
294 "mov %[n2] , %[hi]" "\n\t"
295 "out %[port] , %[lo]" "\n\t"
296 "rjmp .+0" "\n\t"
297 "out %[port] , %[hi]" "\n\t"
298 "mov %[n1] , %[lo]" "\n\t"
299 "out %[port] , %[n2]" "\n\t"
300 "rjmp .+0" "\n\t"
301 "sbrc %[byte] , 1" "\n\t"
302 "mov %[n1] , %[hi]" "\n\t"
303 "out %[port] , %[lo]" "\n\t"
304 "rjmp .+0" "\n\t"
305 "out %[port] , %[hi]" "\n\t"
306 "mov %[n2] , %[lo]" "\n\t"
307 "out %[port] , %[n1]" "\n\t"
308 "rjmp .+0" "\n\t"
309 "sbrc %[byte] , 0" "\n\t"
310 "mov %[n2] , %[hi]" "\n\t"
311 "out %[port] , %[lo]" "\n\t"
312 "sbiw %[count], 1" "\n\t"
313 "out %[port] , %[hi]" "\n\t"
314 "mov %[n1] , %[lo]" "\n\t"
315 "out %[port] , %[n2]" "\n\t"
316 "ld %[byte] , %a[ptr]+" "\n\t"
317 "sbrc %[byte] , 7" "\n\t"
318 "mov %[n1] , %[hi]" "\n\t"
319 "out %[port] , %[lo]" "\n\t"
320 "brne headB" "\n"
321 : [byte] "+r" (b), [n1] "+r" (n1), [n2] "+r" (n2), [count] "+w" (i)
322 : [port] "I" (_SFR_IO_ADDR(PORTB)), [ptr] "e" (ptr), [hi] "r" (hi),
323 [lo] "r" (lo));
324
325 #ifdef PORTD
326 } // endif PORTB
327 #endif
328
329 #ifdef NEO_KHZ400
330 } else { // end 800 KHz, do 400 KHz
331
332 // Timing is more relaxed; unrolling the inner loop for each bit is
333 // not necessary. Still using the peculiar RJMPs as 2X NOPs, not out
334 // of need but just to trim the code size down a little.
335 // This 400-KHz-datastream-on-8-MHz-CPU code is not quite identical
336 // to the 800-on-16 code later -- the hi/lo timing between WS2811 and
337 // WS2812 is not simply a 2:1 scale!
338
339 // 20 inst. clocks per bit: HHHHxxxxxxLLLLLLLLLL
340 // ST instructions: ^ ^ ^ (T=0,4,10)
341
342 volatile uint8_t next, bit;
343
344 hi = *port | pinMask;
345 lo = *port & ~pinMask;
346 next = lo;
347 bit = 8;
348
349 asm volatile(
350 "head20:" "\n\t" // Clk Pseudocode (T = 0)
351 "st %a[port], %[hi]" "\n\t" // 2 PORT = hi (T = 2)
352 "sbrc %[byte] , 7" "\n\t" // 1-2 if(b & 128)
353 "mov %[next], %[hi]" "\n\t" // 0-1 next = hi (T = 4)
354 "st %a[port], %[next]" "\n\t" // 2 PORT = next (T = 6)
355 "mov %[next] , %[lo]" "\n\t" // 1 next = lo (T = 7)
356 "dec %[bit]" "\n\t" // 1 bit-- (T = 8)
357 "breq nextbyte20" "\n\t" // 1-2 if(bit == 0)
358 "rol %[byte]" "\n\t" // 1 b <<= 1 (T = 10)
359 "st %a[port], %[lo]" "\n\t" // 2 PORT = lo (T = 12)
360 "rjmp .+0" "\n\t" // 2 nop nop (T = 14)
361 "rjmp .+0" "\n\t" // 2 nop nop (T = 16)
362 "rjmp .+0" "\n\t" // 2 nop nop (T = 18)
363 "rjmp head20" "\n\t" // 2 -> head20 (next bit out)
364 "nextbyte20:" "\n\t" // (T = 10)
365 "st %a[port], %[lo]" "\n\t" // 2 PORT = lo (T = 12)
366 "nop" "\n\t" // 1 nop (T = 13)
367 "ldi %[bit] , 8" "\n\t" // 1 bit = 8 (T = 14)
368 "ld %[byte] , %a[ptr]+" "\n\t" // 2 b = *ptr++ (T = 16)
369 "sbiw %[count], 1" "\n\t" // 2 i-- (T = 18)
370 "brne head20" "\n" // 2 if(i != 0) -> (next byte)
371 : [port] "+e" (port),
372 [byte] "+r" (b),
373 [bit] "+r" (bit),
374 [next] "+r" (next),
375 [count] "+w" (i)
376 : [hi] "r" (hi),
377 [lo] "r" (lo),
378 [ptr] "e" (ptr));
379 }
380 #endif
381
382 // 12 MHz(ish) AVR --------------------------------------------------------
383 #elif (F_CPU >= 11100000UL) && (F_CPU <= 14300000UL)
384
385 #ifdef NEO_KHZ400
386 if((type & NEO_SPDMASK) == NEO_KHZ800) { // 800 KHz bitstream
387 #endif
388
389 // In the 12 MHz case, an optimized 800 KHz datastream (no dead time
390 // between bytes) requires a PORT-specific loop similar to the 8 MHz
391 // code (but a little more relaxed in this case).
392
393 // 15 instruction clocks per bit: HHHHxxxxxxLLLLL
394 // OUT instructions: ^ ^ ^ (T=0,4,10)
395
396 volatile uint8_t next;
397
398 #ifdef PORTD
399
400 if(port == &PORTD) {
401
402 hi = PORTD | pinMask;
403 lo = PORTD & ~pinMask;
404 next = lo;
405 if(b & 0x80) next = hi;
406
407 // Don't "optimize" the OUT calls into the bitTime subroutine;
408 // we're exploiting the RCALL and RET as 3- and 4-cycle NOPs!
409 asm volatile(
410 "headD:" "\n\t" // (T = 0)
411 "out %[port], %[hi]" "\n\t" // (T = 1)
412 "rcall bitTimeD" "\n\t" // Bit 7 (T = 15)
413 "out %[port], %[hi]" "\n\t"
414 "rcall bitTimeD" "\n\t" // Bit 6
415 "out %[port], %[hi]" "\n\t"
416 "rcall bitTimeD" "\n\t" // Bit 5
417 "out %[port], %[hi]" "\n\t"
418 "rcall bitTimeD" "\n\t" // Bit 4
419 "out %[port], %[hi]" "\n\t"
420 "rcall bitTimeD" "\n\t" // Bit 3
421 "out %[port], %[hi]" "\n\t"
422 "rcall bitTimeD" "\n\t" // Bit 2
423 "out %[port], %[hi]" "\n\t"
424 "rcall bitTimeD" "\n\t" // Bit 1
425 // Bit 0:
426 "out %[port] , %[hi]" "\n\t" // 1 PORT = hi (T = 1)
427 "rjmp .+0" "\n\t" // 2 nop nop (T = 3)
428 "ld %[byte] , %a[ptr]+" "\n\t" // 2 b = *ptr++ (T = 5)
429 "out %[port] , %[next]" "\n\t" // 1 PORT = next (T = 6)
430 "mov %[next] , %[lo]" "\n\t" // 1 next = lo (T = 7)
431 "sbrc %[byte] , 7" "\n\t" // 1-2 if(b & 0x80) (T = 8)
432 "mov %[next] , %[hi]" "\n\t" // 0-1 next = hi (T = 9)
433 "nop" "\n\t" // 1 (T = 10)
434 "out %[port] , %[lo]" "\n\t" // 1 PORT = lo (T = 11)
435 "sbiw %[count], 1" "\n\t" // 2 i-- (T = 13)
436 "brne headD" "\n\t" // 2 if(i != 0) -> (next byte)
437 "rjmp doneD" "\n\t"
438 "bitTimeD:" "\n\t" // nop nop nop (T = 4)
439 "out %[port], %[next]" "\n\t" // 1 PORT = next (T = 5)
440 "mov %[next], %[lo]" "\n\t" // 1 next = lo (T = 6)
441 "rol %[byte]" "\n\t" // 1 b <<= 1 (T = 7)
442 "sbrc %[byte], 7" "\n\t" // 1-2 if(b & 0x80) (T = 8)
443 "mov %[next], %[hi]" "\n\t" // 0-1 next = hi (T = 9)
444 "nop" "\n\t" // 1 (T = 10)
445 "out %[port], %[lo]" "\n\t" // 1 PORT = lo (T = 11)
446 "ret" "\n\t" // 4 nop nop nop nop (T = 15)
447 "doneD:" "\n"
448 : [byte] "+r" (b),
449 [next] "+r" (next),
450 [count] "+w" (i)
451 : [port] "I" (_SFR_IO_ADDR(PORTD)),
452 [ptr] "e" (ptr),
453 [hi] "r" (hi),
454 [lo] "r" (lo));
455
456 } else if(port == &PORTB) {
457
458 #endif // PORTD
459
460 hi = PORTB | pinMask;
461 lo = PORTB & ~pinMask;
462 next = lo;
463 if(b & 0x80) next = hi;
464
465 // Same as above, just set for PORTB & stripped of comments
466 asm volatile(
467 "headB:" "\n\t"
468 "out %[port], %[hi]" "\n\t"
469 "rcall bitTimeB" "\n\t"
470 "out %[port], %[hi]" "\n\t"
471 "rcall bitTimeB" "\n\t"
472 "out %[port], %[hi]" "\n\t"
473 "rcall bitTimeB" "\n\t"
474 "out %[port], %[hi]" "\n\t"
475 "rcall bitTimeB" "\n\t"
476 "out %[port], %[hi]" "\n\t"
477 "rcall bitTimeB" "\n\t"
478 "out %[port], %[hi]" "\n\t"
479 "rcall bitTimeB" "\n\t"
480 "out %[port], %[hi]" "\n\t"
481 "rcall bitTimeB" "\n\t"
482 "out %[port] , %[hi]" "\n\t"
483 "rjmp .+0" "\n\t"
484 "ld %[byte] , %a[ptr]+" "\n\t"
485 "out %[port] , %[next]" "\n\t"
486 "mov %[next] , %[lo]" "\n\t"
487 "sbrc %[byte] , 7" "\n\t"
488 "mov %[next] , %[hi]" "\n\t"
489 "nop" "\n\t"
490 "out %[port] , %[lo]" "\n\t"
491 "sbiw %[count], 1" "\n\t"
492 "brne headB" "\n\t"
493 "rjmp doneB" "\n\t"
494 "bitTimeB:" "\n\t"
495 "out %[port], %[next]" "\n\t"
496 "mov %[next], %[lo]" "\n\t"
497 "rol %[byte]" "\n\t"
498 "sbrc %[byte], 7" "\n\t"
499 "mov %[next], %[hi]" "\n\t"
500 "nop" "\n\t"
501 "out %[port], %[lo]" "\n\t"
502 "ret" "\n\t"
503 "doneB:" "\n"
504 : [byte] "+r" (b), [next] "+r" (next), [count] "+w" (i)
505 : [port] "I" (_SFR_IO_ADDR(PORTB)), [ptr] "e" (ptr), [hi] "r" (hi),
506 [lo] "r" (lo));
507
508 #ifdef PORTD
509 }
510 #endif
511
512 #ifdef NEO_KHZ400
513 } else { // 400 KHz
514
515 // 30 instruction clocks per bit: HHHHHHxxxxxxxxxLLLLLLLLLLLLLLL
516 // ST instructions: ^ ^ ^ (T=0,6,15)
517
518 volatile uint8_t next, bit;
519
520 hi = *port | pinMask;
521 lo = *port & ~pinMask;
522 next = lo;
523 bit = 8;
524
525 asm volatile(
526 "head30:" "\n\t" // Clk Pseudocode (T = 0)
527 "st %a[port], %[hi]" "\n\t" // 2 PORT = hi (T = 2)
528 "sbrc %[byte] , 7" "\n\t" // 1-2 if(b & 128)
529 "mov %[next], %[hi]" "\n\t" // 0-1 next = hi (T = 4)
530 "rjmp .+0" "\n\t" // 2 nop nop (T = 6)
531 "st %a[port], %[next]" "\n\t" // 2 PORT = next (T = 8)
532 "rjmp .+0" "\n\t" // 2 nop nop (T = 10)
533 "rjmp .+0" "\n\t" // 2 nop nop (T = 12)
534 "rjmp .+0" "\n\t" // 2 nop nop (T = 14)
535 "nop" "\n\t" // 1 nop (T = 15)
536 "st %a[port], %[lo]" "\n\t" // 2 PORT = lo (T = 17)
537 "rjmp .+0" "\n\t" // 2 nop nop (T = 19)
538 "dec %[bit]" "\n\t" // 1 bit-- (T = 20)
539 "breq nextbyte30" "\n\t" // 1-2 if(bit == 0)
540 "rol %[byte]" "\n\t" // 1 b <<= 1 (T = 22)
541 "rjmp .+0" "\n\t" // 2 nop nop (T = 24)
542 "rjmp .+0" "\n\t" // 2 nop nop (T = 26)
543 "rjmp .+0" "\n\t" // 2 nop nop (T = 28)
544 "rjmp head30" "\n\t" // 2 -> head30 (next bit out)
545 "nextbyte30:" "\n\t" // (T = 22)
546 "nop" "\n\t" // 1 nop (T = 23)
547 "ldi %[bit] , 8" "\n\t" // 1 bit = 8 (T = 24)
548 "ld %[byte] , %a[ptr]+" "\n\t" // 2 b = *ptr++ (T = 26)
549 "sbiw %[count], 1" "\n\t" // 2 i-- (T = 28)
550 "brne head30" "\n" // 1-2 if(i != 0) -> (next byte)
551 : [port] "+e" (port),
552 [byte] "+r" (b),
553 [bit] "+r" (bit),
554 [next] "+r" (next),
555 [count] "+w" (i)
556 : [hi] "r" (hi),
557 [lo] "r" (lo),
558 [ptr] "e" (ptr));
559 }
560 #endif
561
562 // 16 MHz(ish) AVR --------------------------------------------------------
563 #elif (F_CPU >= 15400000UL) && (F_CPU <= 19000000L)
564
565 #ifdef NEO_KHZ400
566 if((type & NEO_SPDMASK) == NEO_KHZ800) { // 800 KHz bitstream
567 #endif
568
569 // WS2811 and WS2812 have different hi/lo duty cycles; this is
570 // similar but NOT an exact copy of the prior 400-on-8 code.
571
572 // 20 inst. clocks per bit: HHHHHxxxxxxxxLLLLLLL
573 // ST instructions: ^ ^ ^ (T=0,5,13)
574
575 volatile uint8_t next, bit;
576
577 hi = *port | pinMask;
578 lo = *port & ~pinMask;
579 next = lo;
580 bit = 8;
581
582 asm volatile(
583 "head20:" "\n\t" // Clk Pseudocode (T = 0)
584 "st %a[port], %[hi]" "\n\t" // 2 PORT = hi (T = 2)
585 "sbrc %[byte], 7" "\n\t" // 1-2 if(b & 128)
586 "mov %[next], %[hi]" "\n\t" // 0-1 next = hi (T = 4)
587 "dec %[bit]" "\n\t" // 1 bit-- (T = 5)
588 "st %a[port], %[next]" "\n\t" // 2 PORT = next (T = 7)
589 "mov %[next] , %[lo]" "\n\t" // 1 next = lo (T = 8)
590 "breq nextbyte20" "\n\t" // 1-2 if(bit == 0) (from dec above)
591 "rol %[byte]" "\n\t" // 1 b <<= 1 (T = 10)
592 "rjmp .+0" "\n\t" // 2 nop nop (T = 12)
593 "nop" "\n\t" // 1 nop (T = 13)
594 "st %a[port], %[lo]" "\n\t" // 2 PORT = lo (T = 15)
595 "nop" "\n\t" // 1 nop (T = 16)
596 "rjmp .+0" "\n\t" // 2 nop nop (T = 18)
597 "rjmp head20" "\n\t" // 2 -> head20 (next bit out)
598 "nextbyte20:" "\n\t" // (T = 10)
599 "ldi %[bit] , 8" "\n\t" // 1 bit = 8 (T = 11)
600 "ld %[byte] , %a[ptr]+" "\n\t" // 2 b = *ptr++ (T = 13)
601 "st %a[port], %[lo]" "\n\t" // 2 PORT = lo (T = 15)
602 "nop" "\n\t" // 1 nop (T = 16)
603 "sbiw %[count], 1" "\n\t" // 2 i-- (T = 18)
604 "brne head20" "\n" // 2 if(i != 0) -> (next byte)
605 : [port] "+e" (port),
606 [byte] "+r" (b),
607 [bit] "+r" (bit),
608 [next] "+r" (next),
609 [count] "+w" (i)
610 : [ptr] "e" (ptr),
611 [hi] "r" (hi),
612 [lo] "r" (lo));
613
614 #ifdef NEO_KHZ400
615 } else { // 400 KHz
616
617 // The 400 KHz clock on 16 MHz MCU is the most 'relaxed' version.
618
619 // 40 inst. clocks per bit: HHHHHHHHxxxxxxxxxxxxLLLLLLLLLLLLLLLLLLLL
620 // ST instructions: ^ ^ ^ (T=0,8,20)
621
622 volatile uint8_t next, bit;
623
624 hi = *port | pinMask;
625 lo = *port & ~pinMask;
626 next = lo;
627 bit = 8;
628
629 asm volatile(
630 "head40:" "\n\t" // Clk Pseudocode (T = 0)
631 "st %a[port], %[hi]" "\n\t" // 2 PORT = hi (T = 2)
632 "sbrc %[byte] , 7" "\n\t" // 1-2 if(b & 128)
633 "mov %[next] , %[hi]" "\n\t" // 0-1 next = hi (T = 4)
634 "rjmp .+0" "\n\t" // 2 nop nop (T = 6)
635 "rjmp .+0" "\n\t" // 2 nop nop (T = 8)
636 "st %a[port], %[next]" "\n\t" // 2 PORT = next (T = 10)
637 "rjmp .+0" "\n\t" // 2 nop nop (T = 12)
638 "rjmp .+0" "\n\t" // 2 nop nop (T = 14)
639 "rjmp .+0" "\n\t" // 2 nop nop (T = 16)
640 "rjmp .+0" "\n\t" // 2 nop nop (T = 18)
641 "rjmp .+0" "\n\t" // 2 nop nop (T = 20)
642 "st %a[port], %[lo]" "\n\t" // 2 PORT = lo (T = 22)
643 "nop" "\n\t" // 1 nop (T = 23)
644 "mov %[next] , %[lo]" "\n\t" // 1 next = lo (T = 24)
645 "dec %[bit]" "\n\t" // 1 bit-- (T = 25)
646 "breq nextbyte40" "\n\t" // 1-2 if(bit == 0)
647 "rol %[byte]" "\n\t" // 1 b <<= 1 (T = 27)
648 "nop" "\n\t" // 1 nop (T = 28)
649 "rjmp .+0" "\n\t" // 2 nop nop (T = 30)
650 "rjmp .+0" "\n\t" // 2 nop nop (T = 32)
651 "rjmp .+0" "\n\t" // 2 nop nop (T = 34)
652 "rjmp .+0" "\n\t" // 2 nop nop (T = 36)
653 "rjmp .+0" "\n\t" // 2 nop nop (T = 38)
654 "rjmp head40" "\n\t" // 2 -> head40 (next bit out)
655 "nextbyte40:" "\n\t" // (T = 27)
656 "ldi %[bit] , 8" "\n\t" // 1 bit = 8 (T = 28)
657 "ld %[byte] , %a[ptr]+" "\n\t" // 2 b = *ptr++ (T = 30)
658 "rjmp .+0" "\n\t" // 2 nop nop (T = 32)
659 "st %a[port], %[lo]" "\n\t" // 2 PORT = lo (T = 34)
660 "rjmp .+0" "\n\t" // 2 nop nop (T = 36)
661 "sbiw %[count], 1" "\n\t" // 2 i-- (T = 38)
662 "brne head40" "\n" // 1-2 if(i != 0) -> (next byte)
663 : [port] "+e" (port),
664 [byte] "+r" (b),
665 [bit] "+r" (bit),
666 [next] "+r" (next),
667 [count] "+w" (i)
668 : [ptr] "e" (ptr),
669 [hi] "r" (hi),
670 [lo] "r" (lo));
671 }
672 #endif
673
674 #else
675 #error "CPU SPEED NOT SUPPORTED"
676 #endif
677
678 #elif defined(__arm__)
679
680 #if defined(__MK20DX128__) || defined(__MK20DX256__) // Teensy 3.0 & 3.1
681 #define CYCLES_800_T0H (F_CPU / 4000000)
682 #define CYCLES_800_T1H (F_CPU / 1250000)
683 #define CYCLES_800 (F_CPU / 800000)
684 #define CYCLES_400_T0H (F_CPU / 2000000)
685 #define CYCLES_400_T1H (F_CPU / 833333)
686 #define CYCLES_400 (F_CPU / 400000)
687
688 uint8_t *p = pixels,
689 *end = p + numBytes, pix, mask;
690 volatile uint8_t *set = portSetRegister(pin),
691 *clr = portClearRegister(pin);
692 uint32_t cyc;
693
694 ARM_DEMCR |= ARM_DEMCR_TRCENA;
695 ARM_DWT_CTRL |= ARM_DWT_CTRL_CYCCNTENA;
696
697 #ifdef NEO_KHZ400
698 if((type & NEO_SPDMASK) == NEO_KHZ800) { // 800 KHz bitstream
699 #endif
700 cyc = ARM_DWT_CYCCNT + CYCLES_800;
701 while(p < end) {
702 pix = *p++;
703 for(mask = 0x80; mask; mask >>= 1) {
704 while(ARM_DWT_CYCCNT - cyc < CYCLES_800);
705 cyc = ARM_DWT_CYCCNT;
706 *set = 1;
707 if(pix & mask) {
708 while(ARM_DWT_CYCCNT - cyc < CYCLES_800_T1H);
709 } else {
710 while(ARM_DWT_CYCCNT - cyc < CYCLES_800_T0H);
711 }
712 *clr = 1;
713 }
714 }
715 while(ARM_DWT_CYCCNT - cyc < CYCLES_800);
716 #ifdef NEO_KHZ400
717 } else { // 400 kHz bitstream
718 cyc = ARM_DWT_CYCCNT + CYCLES_400;
719 while(p < end) {
720 pix = *p++;
721 for(mask = 0x80; mask; mask >>= 1) {
722 while(ARM_DWT_CYCCNT - cyc < CYCLES_400);
723 cyc = ARM_DWT_CYCCNT;
724 *set = 1;
725 if(pix & mask) {
726 while(ARM_DWT_CYCCNT - cyc < CYCLES_400_T1H);
727 } else {
728 while(ARM_DWT_CYCCNT - cyc < CYCLES_400_T0H);
729 }
730 *clr = 1;
731 }
732 }
733 while(ARM_DWT_CYCCNT - cyc < CYCLES_400);
734 }
735 #endif
736
737
738
739
740
741 #elif defined(__MKL26Z64__) // Teensy-LC
742
743 #if F_CPU == 48000000
744 uint8_t *p = pixels,
745 pix, count, dly,
746 bitmask = digitalPinToBitMask(pin);
747 volatile uint8_t *reg = portSetRegister(pin);
748 uint32_t num = numBytes;
749 asm volatile(
750 "L%=_begin:" "\n\t"
751 "ldrb %[pix], [%[p], #0]" "\n\t"
752 "lsl %[pix], #24" "\n\t"
753 "movs %[count], #7" "\n\t"
754 "L%=_loop:" "\n\t"
755 "lsl %[pix], #1" "\n\t"
756 "bcs L%=_loop_one" "\n\t"
757 "L%=_loop_zero:"
758 "strb %[bitmask], [%[reg], #0]" "\n\t"
759 "movs %[dly], #4" "\n\t"
760 "L%=_loop_delay_T0H:" "\n\t"
761 "sub %[dly], #1" "\n\t"
762 "bne L%=_loop_delay_T0H" "\n\t"
763 "strb %[bitmask], [%[reg], #4]" "\n\t"
764 "movs %[dly], #13" "\n\t"
765 "L%=_loop_delay_T0L:" "\n\t"
766 "sub %[dly], #1" "\n\t"
767 "bne L%=_loop_delay_T0L" "\n\t"
768 "b L%=_next" "\n\t"
769 "L%=_loop_one:"
770 "strb %[bitmask], [%[reg], #0]" "\n\t"
771 "movs %[dly], #13" "\n\t"
772 "L%=_loop_delay_T1H:" "\n\t"
773 "sub %[dly], #1" "\n\t"
774 "bne L%=_loop_delay_T1H" "\n\t"
775 "strb %[bitmask], [%[reg], #4]" "\n\t"
776 "movs %[dly], #4" "\n\t"
777 "L%=_loop_delay_T1L:" "\n\t"
778 "sub %[dly], #1" "\n\t"
779 "bne L%=_loop_delay_T1L" "\n\t"
780 "nop" "\n\t"
781 "L%=_next:" "\n\t"
782 "sub %[count], #1" "\n\t"
783 "bne L%=_loop" "\n\t"
784 "lsl %[pix], #1" "\n\t"
785 "bcs L%=_last_one" "\n\t"
786 "L%=_last_zero:"
787 "strb %[bitmask], [%[reg], #0]" "\n\t"
788 "movs %[dly], #4" "\n\t"
789 "L%=_last_delay_T0H:" "\n\t"
790 "sub %[dly], #1" "\n\t"
791 "bne L%=_last_delay_T0H" "\n\t"
792 "strb %[bitmask], [%[reg], #4]" "\n\t"
793 "movs %[dly], #10" "\n\t"
794 "L%=_last_delay_T0L:" "\n\t"
795 "sub %[dly], #1" "\n\t"
796 "bne L%=_last_delay_T0L" "\n\t"
797 "b L%=_repeat" "\n\t"
798 "L%=_last_one:"
799 "strb %[bitmask], [%[reg], #0]" "\n\t"
800 "movs %[dly], #13" "\n\t"
801 "L%=_last_delay_T1H:" "\n\t"
802 "sub %[dly], #1" "\n\t"
803 "bne L%=_last_delay_T1H" "\n\t"
804 "strb %[bitmask], [%[reg], #4]" "\n\t"
805 "movs %[dly], #1" "\n\t"
806 "L%=_last_delay_T1L:" "\n\t"
807 "sub %[dly], #1" "\n\t"
808 "bne L%=_last_delay_T1L" "\n\t"
809 "nop" "\n\t"
810 "L%=_repeat:" "\n\t"
811 "add %[p], #1" "\n\t"
812 "sub %[num], #1" "\n\t"
813 "bne L%=_begin" "\n\t"
814 "L%=_done:" "\n\t"
815 : [p] "+r" (p),
816 [pix] "=&r" (pix),
817 [count] "=&r" (count),
818 [dly] "=&r" (dly),
819 [num] "+r" (num)
820 : [bitmask] "r" (bitmask),
821 [reg] "r" (reg)
822 );
823 #else
824 #error "Sorry, only 48 MHz is supported, please set Tools > CPU Speed to 48 MHz"
825 #endif
826
827
828 #else // Arduino Due
829
830 #define SCALE VARIANT_MCK / 2UL / 1000000UL
831 #define INST (2UL * F_CPU / VARIANT_MCK)
832 #define TIME_800_0 ((int)(0.40 * SCALE + 0.5) - (5 * INST))
833 #define TIME_800_1 ((int)(0.80 * SCALE + 0.5) - (5 * INST))
834 #define PERIOD_800 ((int)(1.25 * SCALE + 0.5) - (5 * INST))
835 #define TIME_400_0 ((int)(0.50 * SCALE + 0.5) - (5 * INST))
836 #define TIME_400_1 ((int)(1.20 * SCALE + 0.5) - (5 * INST))
837 #define PERIOD_400 ((int)(2.50 * SCALE + 0.5) - (5 * INST))
838
839 int pinMask, time0, time1, period, t;
840 Pio *port;
841 volatile WoReg *portSet, *portClear, *timeValue, *timeReset;
842 uint8_t *p, *end, pix, mask;
843
844 pmc_set_writeprotect(false);
845 pmc_enable_periph_clk((uint32_t)TC3_IRQn);
846 TC_Configure(TC1, 0,
847 TC_CMR_WAVE | TC_CMR_WAVSEL_UP | TC_CMR_TCCLKS_TIMER_CLOCK1);
848 TC_Start(TC1, 0);
849
850 pinMask = g_APinDescription[pin].ulPin; // Don't 'optimize' these into
851 port = g_APinDescription[pin].pPort; // declarations above. Want to
852 portSet = &(port->PIO_SODR); // burn a few cycles after
853 portClear = &(port->PIO_CODR); // starting timer to minimize
854 timeValue = &(TC1->TC_CHANNEL[0].TC_CV); // the initial 'while'.
855 timeReset = &(TC1->TC_CHANNEL[0].TC_CCR);
856 p = pixels;
857 end = p + numBytes;
858 pix = *p++;
859 mask = 0x80;
860
861 #ifdef NEO_KHZ400
862 if((type & NEO_SPDMASK) == NEO_KHZ800) { // 800 KHz bitstream
863 #endif
864 time0 = TIME_800_0;
865 time1 = TIME_800_1;
866 period = PERIOD_800;
867 #ifdef NEO_KHZ400
868 } else { // 400 KHz bitstream
869 time0 = TIME_400_0;
870 time1 = TIME_400_1;
871 period = PERIOD_400;
872 }
873 #endif
874
875 for(t = time0;; t = time0) {
876 if(pix & mask) t = time1;
877 while(*timeValue < period);
878 *portSet = pinMask;
879 *timeReset = TC_CCR_CLKEN | TC_CCR_SWTRG;
880 while(*timeValue < t);
881 *portClear = pinMask;
882 if(!(mask >>= 1)) { // This 'inside-out' loop logic utilizes
883 if(p >= end) break; // idle time to minimize inter-byte delays.
884 pix = *p++;
885 mask = 0x80;
886 }
887 }
888 while(*timeValue < period); // Wait for last bit
889 TC_Stop(TC1, 0);
890
891 #endif // end Arduino Due
892
893 #endif // end Architecture select
894
895 interrupts();
896 endTime = micros(); // Save EOD time for latch on next call
897 }
898
899 // Set the output pin number
900 void Adafruit_NeoPixel::setPin(uint8_t p) {
901 pinMode(pin, INPUT);
902 pin = p;
903 pinMode(p, OUTPUT);
904 digitalWrite(p, LOW);
905 #ifdef __AVR__
906 port = portOutputRegister(digitalPinToPort(p));
907 pinMask = digitalPinToBitMask(p);
908 #endif
909 }
910
911 // Set pixel color from separate R,G,B components:
912 void Adafruit_NeoPixel::setPixelColor(
913 uint16_t n, uint8_t r, uint8_t g, uint8_t b) {
914 if(n < numLEDs) {
915 if(brightness) { // See notes in setBrightness()
916 r = (r * brightness) >> 8;
917 g = (g * brightness) >> 8;
918 b = (b * brightness) >> 8;
919 }
920 uint8_t *p = &pixels[n * 3];
921 p[rOffset] = r;
922 p[gOffset] = g;
923 p[bOffset] = b;
924 }
925 }
926
927 // Set pixel color from 'packed' 32-bit RGB color:
928 void Adafruit_NeoPixel::setPixelColor(uint16_t n, uint32_t c) {
929 if(n < numLEDs) {
930 uint8_t
931 r = (uint8_t)(c >> 16),
932 g = (uint8_t)(c >> 8),
933 b = (uint8_t)c;
934 if(brightness) { // See notes in setBrightness()
935 r = (r * brightness) >> 8;
936 g = (g * brightness) >> 8;
937 b = (b * brightness) >> 8;
938 }
939 uint8_t *p = &pixels[n * 3];
940 p[rOffset] = r;
941 p[gOffset] = g;
942 p[bOffset] = b;
943 }
944 }
945
946 // Convert separate R,G,B into packed 32-bit RGB color.
947 // Packed format is always RGB, regardless of LED strand color order.
948 uint32_t Adafruit_NeoPixel::Color(uint8_t r, uint8_t g, uint8_t b) {
949 return ((uint32_t)r << 16) | ((uint32_t)g << 8) | b;
950 }
951
952 // Query color from previously-set pixel (returns packed 32-bit RGB value)
953 uint32_t Adafruit_NeoPixel::getPixelColor(uint16_t n) const {
954 if(n >= numLEDs) {
955 // Out of bounds, return no color.
956 return 0;
957 }
958 uint8_t *p = &pixels[n * 3];
959 uint32_t c = ((uint32_t)p[rOffset] << 16) |
960 ((uint32_t)p[gOffset] << 8) |
961 (uint32_t)p[bOffset];
962 // Adjust this back up to the true color, as setting a pixel color will
963 // scale it back down again.
964 if(brightness) { // See notes in setBrightness()
965 //Cast the color to a byte array
966 uint8_t * c_ptr =reinterpret_cast<uint8_t*>(&c);
967 c_ptr[0] = (c_ptr[0] << 8)/brightness;
968 c_ptr[1] = (c_ptr[1] << 8)/brightness;
969 c_ptr[2] = (c_ptr[2] << 8)/brightness;
970 }
971 return c; // Pixel # is out of bounds
972 }
973
974 // Returns pointer to pixels[] array. Pixel data is stored in device-
975 // native format and is not translated here. Application will need to be
976 // aware whether pixels are RGB vs. GRB and handle colors appropriately.
977 uint8_t *Adafruit_NeoPixel::getPixels(void) const {
978 return pixels;
979 }
980
981 uint16_t Adafruit_NeoPixel::numPixels(void) const {
982 return numLEDs;
983 }
984
985 // Adjust output brightness; 0=darkest (off), 255=brightest. This does
986 // NOT immediately affect what's currently displayed on the LEDs. The
987 // next call to show() will refresh the LEDs at this level. However,
988 // this process is potentially "lossy," especially when increasing
989 // brightness. The tight timing in the WS2811/WS2812 code means there
990 // aren't enough free cycles to perform this scaling on the fly as data
991 // is issued. So we make a pass through the existing color data in RAM
992 // and scale it (subsequent graphics commands also work at this
993 // brightness level). If there's a significant step up in brightness,
994 // the limited number of steps (quantization) in the old data will be
995 // quite visible in the re-scaled version. For a non-destructive
996 // change, you'll need to re-render the full strip data. C'est la vie.
997 void Adafruit_NeoPixel::setBrightness(uint8_t b) {
998 // Stored brightness value is different than what's passed.
999 // This simplifies the actual scaling math later, allowing a fast
1000 // 8x8-bit multiply and taking the MSB. 'brightness' is a uint8_t,
1001 // adding 1 here may (intentionally) roll over...so 0 = max brightness
1002 // (color values are interpreted literally; no scaling), 1 = min
1003 // brightness (off), 255 = just below max brightness.
1004 uint8_t newBrightness = b + 1;
1005 if(newBrightness != brightness) { // Compare against prior value
1006 // Brightness has changed -- re-scale existing data in RAM
1007 uint8_t c,
1008 *ptr = pixels,
1009 oldBrightness = brightness - 1; // De-wrap old brightness value
1010 uint16_t scale;
1011 if(oldBrightness == 0) scale = 0; // Avoid /0
1012 else if(b == 255) scale = 65535 / oldBrightness;
1013 else scale = (((uint16_t)newBrightness << 8) - 1) / oldBrightness;
1014 for(uint16_t i=0; i<numBytes; i++) {
1015 c = *ptr;
1016 *ptr++ = (c * scale) >> 8;
1017 }
1018 brightness = newBrightness;
1019 }
1020 }
1021
1022 //Return the brightness value
1023 uint8_t Adafruit_NeoPixel::getBrightness(void) const {
1024 return brightness - 1;
1025 }
1026
1027 void Adafruit_NeoPixel::clear() {
1028 memset(pixels, 0, numBytes);
1029 }