455 lines
13 KiB
C
455 lines
13 KiB
C
/****************************************************************************
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* drivers/leds/ws2812.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/spi/spi.h>
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#include <nuttx/leds/ws2812.h>
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#ifdef CONFIG_WS2812
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* In order to meet the signaling timing requirements, the waveforms required
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* to represent a 0/1 symbol are created by specific SPI bytes defined here.
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*
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* Only two target frequencies: 4 MHz and 8 MHz. However, given the tolerance
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* allowed in the WS2812 timing specs, two ranges around those target
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* frequencies can be used for better flexibility. Extreme frequencies
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* rounded to the nearest multiple of 100 kHz which meets the specs.
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* Try to avoid using the extreme frequencies.
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*
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* If using an LED different to the WS2812 (e.g. WS2812B) check its timing
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* specs, which may vary slightly, to decide which frequency is safe to use.
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*
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* WS2812 specs:
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* T0H range: 200ns - 500ns
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* T1H range: 550ns - 850ns
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* Reset: low signal >50us
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*/
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#if CONFIG_WS2812_FREQUENCY >= 3600000 && CONFIG_WS2812_FREQUENCY <= 5000000
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# define WS2812_ZERO_BYTE 0b01000000 /* 200ns at 5 MHz, 278ns at 3.6 MHz */
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# define WS2812_ONE_BYTE 0b01110000 /* 600ns at 5 MHz, 833ns at 3.6 MHz */
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#elif CONFIG_WS2812_FREQUENCY >= 5900000 && CONFIG_WS2812_FREQUENCY <= 9000000
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# define WS2812_ZERO_BYTE 0b01100000 /* 222ns at 9 MHz, 339ns at 5.9 MHz */
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# define WS2812_ONE_BYTE 0b01111100 /* 556ns at 9 MHz, 847ns at 5.9 MHz */
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#else
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# error "Unsupported SPI Frequency"
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#endif
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/* Reset bytes
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* Number of empty bytes to create the reset low pulse
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* Aiming for 60 us, safely above the 50us required.
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*/
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#define WS2812_RST_CYCLES (CONFIG_WS2812_FREQUENCY * 60 / 1000000 / 8)
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#define WS2812_BYTES_PER_LED (8 * 3)
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#define WS2812_RW_PIXEL_SIZE 4
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/* Transmit buffer looks like:
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* [<----N reset bytes---->|<-RGBn->...<-RGB0->|<----1 reset byte---->]
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*
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* It is important that this is shipped as close to one chunk as possible
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* in order to meet timing requirements and to keep MOSI from going high
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* between transactions. Some chips will leave MOSI at the state of the
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* MSB of the last byte for this reason it is recommended to shift the
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* bits that represents the zero or one waveform so that the MSB is 0.
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* The reset byte after the RGB data will pad the shortened low at the end.
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*/
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#define TXBUFF_SIZE(n) (WS2812_RST_CYCLES + n * WS2812_BYTES_PER_LED + 1)
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/****************************************************************************
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* Private Types
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****************************************************************************/
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struct ws2812_dev_s
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{
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FAR struct spi_dev_s *spi; /* SPI interface */
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uint16_t nleds; /* Number of addressable LEDs */
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uint8_t *tx_buf; /* Buffer for write transaction and state */
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sem_t exclsem; /* Assures exclusive access to the driver */
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};
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static inline void ws2812_configspi(FAR struct spi_dev_s *spi);
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static void ws2812_pack(FAR uint8_t *buf, uint32_t rgb);
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/* Character driver methods */
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static ssize_t ws2812_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t ws2812_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen);
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static off_t ws2812_seek(FAR struct file *filep, off_t offset, int whence);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations g_ws2812fops =
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{
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NULL, /* open */
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NULL, /* close */
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ws2812_read, /* read */
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ws2812_write, /* write */
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ws2812_seek, /* seek */
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NULL, /* ioctl */
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NULL /* poll */
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#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
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, NULL /* unlink */
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#endif
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};
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: ws2812_configspi
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*
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* Description:
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* Set the SPI bus configuration
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*
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****************************************************************************/
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static inline void ws2812_configspi(FAR struct spi_dev_s *spi)
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{
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/* Configure SPI for the WS2812
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* There is no CS on this device we just use MOSI and it is exclusive
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*/
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SPI_LOCK(spi, true); /* Exclusive use of the bus */
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SPI_SETMODE(spi, SPIDEV_MODE3);
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SPI_SETBITS(spi, 8);
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SPI_HWFEATURES(spi, 0);
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SPI_SETFREQUENCY(spi, CONFIG_WS2812_FREQUENCY);
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}
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/****************************************************************************
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* Name: ws2812_pack
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*
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* Description:
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* This writes the expanded SPI transaction to the transaction buffer
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* for a given 24bit RGB value.
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*
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* Input Parameters:
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* buf - The location in the transmit buffer to write.
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* rgb - A 24bit RGB color 8bit red, 8-bit green, 8-bit blue
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*
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****************************************************************************/
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static void ws2812_pack(FAR uint8_t *buf, uint32_t rgb)
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{
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uint8_t bit_idx;
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uint8_t byte_idx;
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uint8_t offset = 0;
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uint8_t color;
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uint32_t grb;
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grb = (rgb & 0x00ff00) << 8;
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grb |= (rgb & 0xff0000) >> 8;
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grb |= rgb & 0x0000ff;
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for (byte_idx = 0; byte_idx < 3; byte_idx++)
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{
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color = (uint8_t)(grb >> (8 * (2 - byte_idx)));
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for (bit_idx = 0; bit_idx < 8; bit_idx++)
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{
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if (color & (1 << (7 - bit_idx)))
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{
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buf[offset] = WS2812_ONE_BYTE;
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}
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else
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{
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buf[offset] = WS2812_ZERO_BYTE;
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}
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offset++;
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}
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}
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}
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/****************************************************************************
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* Name: ws2812_read
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****************************************************************************/
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static ssize_t ws2812_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen)
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{
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return -ENOSYS;
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}
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/****************************************************************************
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* Name: ws2812_write
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*
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* Description:
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* This routine is called when writing to the WS2812 device. Data buffer
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* should be an array of 32bit values holding 24bits of color information
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* in host byte ordering 0x**rrggbb.
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*
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****************************************************************************/
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static ssize_t ws2812_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen)
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{
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FAR struct inode *inode = filep->f_inode;
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FAR struct ws2812_dev_s *priv = inode->i_private;
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FAR uint8_t *tx_pixel;
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FAR uint32_t *pixel_buf = (FAR uint32_t *)buffer;
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size_t cur_led;
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size_t start_led;
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size_t end_led;
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size_t written = 0;
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if (buffer == NULL)
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{
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lederr("ERROR: Buffer is null\n");
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return -EINVAL;
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}
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/* We need at least one LED, so 1 byte */
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if (buflen < 1)
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{
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lederr("ERROR: You need to control at least 1 LED!\n");
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return -EINVAL;
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}
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if ((buflen % WS2812_RW_PIXEL_SIZE) != 0)
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{
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lederr("ERROR: LED values must be 24bit packed in 32bit\n");
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return -EINVAL;
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}
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nxsem_wait(&priv->exclsem);
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start_led = filep->f_pos / WS2812_RW_PIXEL_SIZE;
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tx_pixel = priv->tx_buf + WS2812_RST_CYCLES + \
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start_led * WS2812_BYTES_PER_LED;
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end_led = start_led + (buflen / WS2812_RW_PIXEL_SIZE) - 1;
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ledinfo("Start: %d End: %d\n", start_led, end_led);
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if (end_led > (priv->nleds -1))
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{
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end_led = priv->nleds - 1;
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}
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for (cur_led = start_led; cur_led <= end_led; cur_led++)
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{
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ws2812_pack(tx_pixel, *pixel_buf & 0xffffff);
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pixel_buf++;
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tx_pixel += WS2812_BYTES_PER_LED;
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written += WS2812_RW_PIXEL_SIZE;
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}
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SPI_SNDBLOCK(priv->spi, priv->tx_buf, TXBUFF_SIZE(priv->nleds));
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/* Update LED position and handle case were we wrote the last LED */
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filep->f_pos += written;
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if (end_led == (priv->nleds - 1))
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{
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filep->f_pos -= WS2812_RW_PIXEL_SIZE;
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}
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nxsem_post(&priv->exclsem);
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return written;
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}
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/****************************************************************************
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* Name: ws2812_seek
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*
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* Description:
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* This routine is called when seeking the WS2812 device. This can be used
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* to address the starting LED to write. This should be done on a full
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* color boundary which is 32bits. e.g. LED0 - offset 0, LED 8 - offset 32
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*
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****************************************************************************/
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static off_t ws2812_seek(FAR struct file *filep, off_t offset, int whence)
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{
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FAR struct inode *inode = filep->f_inode;
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FAR struct ws2812_dev_s *priv = inode->i_private;
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off_t maxpos;
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off_t pos;
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if ((offset % WS2812_RW_PIXEL_SIZE) != 0)
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{
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return (off_t)-EINVAL;
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}
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nxsem_wait(&priv->exclsem);
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maxpos = (priv->nleds - 1) * WS2812_RW_PIXEL_SIZE;
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pos = filep->f_pos;
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switch (whence)
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{
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case SEEK_CUR:
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pos += offset;
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if (pos > maxpos)
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{
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pos = maxpos;
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}
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else if (pos < 0)
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{
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pos = 0;
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}
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filep->f_pos = pos;
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break;
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case SEEK_SET:
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pos = offset;
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if (pos > maxpos)
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{
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pos = maxpos;
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}
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else if (pos < 0)
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{
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pos = 0;
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}
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filep->f_pos = pos;
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break;
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case SEEK_END:
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pos = maxpos + offset;
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if (pos > maxpos)
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{
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pos = maxpos;
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}
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else if (pos < 0)
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{
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pos = 0;
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}
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filep->f_pos = pos;
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break;
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default:
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/* Return EINVAL if the whence argument is invalid */
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pos = (off_t)-EINVAL;
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break;
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}
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nxsem_post(&priv->exclsem);
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return pos;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: ws2812_leds_register
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*
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* Description:
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* Register the WS2812 character device as 'devpath'
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*
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* Input Parameters:
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* devpath - The full path to the driver to register. E.g., "/dev/leds0"
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* spi - An instance of the SPI interface to use to communicate with
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* WS2812
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* nleds - Number of addressable LEDs
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*
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* Returned Value:
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* Zero (OK) on success; a negated errno value on failure.
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*
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****************************************************************************/
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int ws2812_leds_register(FAR const char *devpath, FAR struct spi_dev_s *spi,
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uint16_t nleds)
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{
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FAR struct ws2812_dev_s *priv;
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int ret;
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int led;
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/* Initialize the WS2812 device structure */
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priv = (FAR struct ws2812_dev_s *)kmm_malloc(sizeof(struct ws2812_dev_s));
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if (!priv)
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{
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lederr("ERROR: Failed to allocate instance\n");
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return -ENOMEM;
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}
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priv->nleds = nleds;
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priv->tx_buf = (FAR uint8_t *)kmm_zalloc(TXBUFF_SIZE(priv->nleds));
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if (!priv->tx_buf)
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{
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lederr("ERROR: Failed to allocate tx buffer\n");
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kmm_free(priv);
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return -ENOMEM;
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}
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/* Mark LED section of TX buffer as off */
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for (led = 0; led < priv->nleds; led++)
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{
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ws2812_pack(
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priv->tx_buf + WS2812_RST_CYCLES + led * WS2812_BYTES_PER_LED,
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0);
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}
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priv->spi = spi;
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ws2812_configspi(priv->spi);
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nxsem_init(&priv->exclsem, 0, 1);
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SPI_SNDBLOCK(priv->spi, priv->tx_buf, TXBUFF_SIZE(priv->nleds));
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/* Register the character driver */
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ret = register_driver(devpath, &g_ws2812fops, 0666, priv);
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if (ret < 0)
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{
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lederr("ERROR: Failed to register driver: %d\n", ret);
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kmm_free(priv->tx_buf);
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kmm_free(priv);
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}
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return ret;
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}
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#endif /* CONFIG_WS2812 */
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