Difference: NeoPixel (2 vs. 3)

Revision 32021-04-10 - PeterSchmid

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META TOPICPARENT	name="MecrispCubeF405"

NeoPixel

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Timing

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WS2812B https://cdn-shop.adafruit.com/datasheets/WS2812B.pdf

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WS2812B Neopixel

WS2812B data sheet https://cdn-shop.adafruit.com/datasheets/WS2812B.pdf

T0H	0code, high voltage time	0.4us ±150ns
T1H	1code, high voltage time	0.8us ±150ns

Line: 11 to 13

T1L	1code, low voltage time	0.45us ±150ns
RES	low voltage time	Above 50μs

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1 bit takes 1.25 us, 24 bit take 30 us
Timer resolution 0.25 us
MSB first

Line: 18 to 23

HTML Color 0xRRGGBB

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Set/Reset Portpin

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F405

Cyclus = 1 / 168 MHz = 6 ns
Timer Resolution = 1 / 42 MHz = 23.8 ns

#define T0H		15	// 0.4 us, 0.4 us / 23.8 ns = 16.8
#define T1H		32	// 0.8 us, 33.6
#define T0L		34	// 0.85 us, 35.7
#define T1L		17	// 0.45 us, 18.9
#define TRES  	420	// 10 us, 420

WB55

Cyclus = 1 / 32 MHz = 31 ns
Timer Resolution =  1 / 32 MHz = 31 ns

Set/Reset Portpin

GPIO port bit set/reset register GPIOx_BSRR

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Address offset: 0x18, x = A..K

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Address offset: 0x18, x = A..K, D8 = PC0

bit0 .. bit15 bit set
bit16 .. bit31 bit reset

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D8 =

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#define GPIOC_BASE            (AHB1PERIPH_BASE + 0x0800UL)
#define AHB1PERIPH_BASE       (PERIPH_BASE + 0x00020000UL)
#define PERIPH_BASE           0x40000000UL /*!< Peripheral base address in the alias region                                */

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Set Counter

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GPIOC->BSRR

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Set Time Period

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autoreload

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Timer

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Clear Update Flag

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TIM6

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Enable/Disable Timer Interrupt

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Set Counter

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Start/Stop Timer

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TIM6->CNT;

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Set Time Period

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TIM6->ARR; // autoreload

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Clear Update Flag

TIM6->SR; // UIF update interrupt flag

Enable/Disable Timer Interrupt

TIM6->DIER; // UIE update interrupt enable

Start/Stop Timer

TIM6->CR1; // UDIS update disable, CEN counter enable

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Peter Schmid - 2021-04-05

timing-neopixel.png:

META FILEATTACHMENT	attachment="timing-neopixel.png" attr="" comment="" date="1617633491" name="timing-neopixel.png" path="timing-neopixel.png" size="19590" user="PeterSchmid" version="1"

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