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drivers/leds/ws2812: Revert SPI frequency change

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0c3db448bb
added the option to generate the waveforms to drive ws2812 and similar LEDs using different
hardware (e.g. RP2040 PIO instead of SPI).

For that new mode, the concept of CONFIG_WS2812_FREQUENCY is different. Instead of
the SPI frequency (commonly a few MHz), it is the frequency of the actual output waveform
(commonly 400 or 800 kHz).

There was an attempt to express the SPI frequency divided by 10, but it's not actually the
case either (it would be divided by 8).

I think it is clearer to explain in Kconfig what CONFIG_WS2812_FREQUENCY means for each mode
and go back to the previous behaviour for the original SPI mode (also to avoid breaking
out-of-tree boards).
This commit is contained in:
Diego Herranz 2022-08-13 17:33:10 +02:00 committed by Brennan Ashton
parent 2234c005d1
commit e1e89b925f
2 changed files with 12 additions and 8 deletions
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12
drivers/leds/Kconfig
View File

@ -148,9 +148,13 @@ config WS2812_FREQUENCY
default 800000
depends on WS2812
---help---
This is should be set to the bit frequency of the
ws2812s being used. Newer chips use an 800 kHz
bit frequency (the default); although, some older
chips run at 400 kHz.
Frequency in Hz.
On SPI mode (WS2812_NON_SPI_DRIVER not selected), this is
the SPI frequency (commonly a few MHz) to generate the required
waveforms to represent a 0/1 symbol.
On non SPI mode (WS2812_NON_SPI_DRIVER selected), this should be set
to the bit frequency of the ws2812s being used. Newer chips use an
800 kHz bit frequency (the default); although, some older chips run
at 400 kHz.
endmenu # LED Support

8
drivers/leds/ws2812.c
View File

@ -78,10 +78,10 @@
* Reset: low signal >50us
*/
#if CONFIG_WS2812_FREQUENCY >= 360000 && CONFIG_WS2812_FREQUENCY <= 500000
#if CONFIG_WS2812_FREQUENCY >= 3600000 && CONFIG_WS2812_FREQUENCY <= 5000000
# define WS2812_ZERO_BYTE 0b01000000 /* 200ns at 5 MHz, 278ns at 3.6 MHz */
# define WS2812_ONE_BYTE 0b01110000 /* 600ns at 5 MHz, 833ns at 3.6 MHz */
#elif CONFIG_WS2812_FREQUENCY >= 590000 && CONFIG_WS2812_FREQUENCY <= 900000
#elif CONFIG_WS2812_FREQUENCY >= 5900000 && CONFIG_WS2812_FREQUENCY <= 9000000
# define WS2812_ZERO_BYTE 0b01100000 /* 222ns at 9 MHz, 339ns at 5.9 MHz */
# define WS2812_ONE_BYTE 0b01111100 /* 556ns at 9 MHz, 847ns at 5.9 MHz */
#else
@ -93,7 +93,7 @@
* Aiming for 60 us, safely above the 50us required.
*/
#define WS2812_RST_CYCLES (CONFIG_WS2812_FREQUENCY * 60 / 100000 / 8)
#define WS2812_RST_CYCLES (CONFIG_WS2812_FREQUENCY * 60 / 1000000 / 8)
#define WS2812_BYTES_PER_LED (8 * 3)
@ -389,7 +389,7 @@ static inline void ws2812_configspi(FAR struct spi_dev_s *spi)
SPI_SETMODE(spi, SPIDEV_MODE3);
SPI_SETBITS(spi, 8);
SPI_HWFEATURES(spi, 0);
SPI_SETFREQUENCY(spi, 10 * CONFIG_WS2812_FREQUENCY);
SPI_SETFREQUENCY(spi, CONFIG_WS2812_FREQUENCY);
}
/****************************************************************************