drivers/ws281x: add SPI backend #22003
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| Original file line number | Diff line number | Diff line change |
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| /* | ||
| * SPDX-FileCopyrightText: 2026 ML!PA Consulting GmbH. | ||
| * SPDX-License-Identifier: LGPL-2.1-only | ||
| */ | ||
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| /** | ||
| * @ingroup drivers_ws281x | ||
| * @{ | ||
| * | ||
| * @file | ||
| * @brief Implementation of WS281x interface through SPI | ||
| * | ||
| * @author Hugues Larrive <hlarrive@pm.me> | ||
| * @author Fabian Hüßler <fabian.huessler@ml-pa.com> | ||
| * | ||
| * @} | ||
| */ | ||
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| #include <assert.h> | ||
| #include <errno.h> | ||
| #include <stdint.h> | ||
| #include <string.h> | ||
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| #include "compiler_hints.h" | ||
| #include "macros/math.h" | ||
| #include "od.h" | ||
| #include "periph/gpio.h" | ||
| #include "periph/spi.h" | ||
| #include "string_utils.h" | ||
| #include "time_units.h" | ||
| #include "ztimer.h" | ||
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| #include "ws281x.h" | ||
| #include "ws281x_constants.h" | ||
| #include "ws281x_params.h" | ||
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| #define ENABLE_DEBUG 0 | ||
| #include "debug.h" | ||
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| /* Trying to reduce the number of parameters, but you can still overwrite them */ | ||
| /* Duration of one SPI bit in nanoseconds */ | ||
| #define _SPI_NS_PER_BIT (NS_PER_SEC / WS281X_SPI_CLK) | ||
| /* Total SPI bits per WS281x bit (rounded) */ | ||
| #define _SPI_BITS_PER_WS DIV_ROUND(WS281X_T_DATA_NS, _SPI_NS_PER_BIT) | ||
| /* Number of HIGH SPI bits for WS 0 */ | ||
| #define _SPI_BITS_ZERO DIV_ROUND(WS281X_T_DATA_ZERO_NS, _SPI_NS_PER_BIT) | ||
| /* Number of HIGH SPI bits for WS 1 */ | ||
| #define _SPI_BITS_ONE DIV_ROUND_UP(WS281X_T_DATA_ONE_NS, _SPI_NS_PER_BIT) | ||
| /* MSB aligned bit pattern for WS 0 */ | ||
| #define _SPI_NIBBLE_0 (((1U << _SPI_BITS_ZERO) - 1) \ | ||
| << (_SPI_BITS_PER_WS - _SPI_BITS_ZERO)) | ||
| /* MSB aligned bit pattern for WS 1 */ | ||
| #define _SPI_NIBBLE_1 (((1U << _SPI_BITS_ONE) - 1) \ | ||
| << (_SPI_BITS_PER_WS - _SPI_BITS_ONE)) | ||
| /* Number of SPI 0-bytes to trigger a reset */ | ||
| #define _SPI_RESET_BYTES ((WS281X_T_END_US * NS_PER_US) / _SPI_NS_PER_BIT / 8U) | ||
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| MAYBE_UNUSED | ||
| static const uint8_t _WS281X_SPI_NIBBLE_0 = (uint8_t)_SPI_NIBBLE_0; | ||
| MAYBE_UNUSED | ||
| static const uint8_t _WS281X_SPI_NIBBLE_1 = (uint8_t)_SPI_NIBBLE_1; | ||
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| #ifndef WS281X_SPI_NIBBLE_0 | ||
| # define WS281X_SPI_NIBBLE_0 _WS281X_SPI_NIBBLE_0 /* e.g., 0x08: 1000: short high */ | ||
| #endif | ||
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| #ifndef WS281X_SPI_NIBBLE_1 | ||
| # define WS281X_SPI_NIBBLE_1 _WS281X_SPI_NIBBLE_1 /* e.g., 0x0E: 1110: long high */ | ||
| #endif | ||
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| #ifndef WS281X_SPI_BITS_PER_WS_BIT | ||
| # define WS281X_SPI_BITS_PER_WS_BIT _SPI_BITS_PER_WS /* e.g., 4: 4 SPI bits per WS bit */ | ||
| #endif | ||
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crasbe marked this conversation as resolved.
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| typedef struct ws281x_spi_data { | ||
| uint8_t data[WS281X_BYTES_PER_DEVICE * WS281X_SPI_BITS_PER_WS_BIT]; | ||
| } ws281x_spi_data_t; | ||
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| /* Add space for one RESET pulse to eat phantom bit */ | ||
| static uint8_t _spi_buf[_SPI_RESET_BYTES + WS281X_PARAM_NUMOF * sizeof(ws281x_spi_data_t)]; | ||
| static size_t _spi_size; | ||
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| int ws281x_init(ws281x_t *dev, const ws281x_params_t *params) | ||
| { | ||
| if (!dev || !params || !params->buf) { | ||
| return -EINVAL; | ||
| } | ||
| memset(dev, 0, sizeof(*dev)); | ||
| dev->params = *params; | ||
| gpio_clear(dev->params.pin); | ||
| gpio_init(dev->params.pin, GPIO_OUT); | ||
| DEBUG("WS281x SPI encoding: %u bits per WS bit (0: 0x%02X, 1: 0x%02X)\n", | ||
| (unsigned)WS281X_SPI_BITS_PER_WS_BIT, | ||
| WS281X_SPI_NIBBLE_0, | ||
| WS281X_SPI_NIBBLE_1); | ||
| return 0; | ||
| } | ||
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| void ws281x_prepare_transmission(ws281x_t *dev) | ||
| { | ||
| (void)dev; | ||
| memset(_spi_buf, 0, sizeof(_spi_buf)); | ||
| _spi_size = _SPI_RESET_BYTES; | ||
| } | ||
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| void ws281x_end_transmission(ws281x_t *dev) | ||
| { | ||
| (void)dev; | ||
| /* spi_periph_reconfigure is required to keep MOSI line stable low before and after transfer */ | ||
| spi_init_pins(WS281X_SPI_DEV); | ||
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maribu marked this conversation as resolved.
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| spi_acquire(WS281X_SPI_DEV, SPI_CS_UNDEF, SPI_MODE_0, WS281X_SPI_CLK); | ||
| spi_transfer_bytes(WS281X_SPI_DEV, SPI_CS_UNDEF, false, | ||
| _spi_buf, _spi_buf, _spi_size); | ||
| ztimer_sleep(ZTIMER_USEC, WS281X_T_END_US); | ||
| spi_release(WS281X_SPI_DEV); | ||
| gpio_clear(dev->params.pin); | ||
| spi_deinit_pins(WS281X_SPI_DEV); | ||
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benpicco marked this conversation as resolved.
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| gpio_init(dev->params.pin, GPIO_OUT); | ||
| /* Can get the size when LED chain tail is connected to MISO */ | ||
| const uint8_t *non_zero_spi_byte = memchk(_spi_buf, 0x00, sizeof(_spi_buf)); | ||
| if (non_zero_spi_byte) { | ||
| size_t led_numof = (non_zero_spi_byte - _spi_buf) / sizeof(ws281x_spi_data_t); | ||
| led_numof -= (_SPI_RESET_BYTES / sizeof(ws281x_spi_data_t)); | ||
| dev->params.numof = led_numof; | ||
| DEBUG("Detected %u LEDs in chain\n", (unsigned)dev->params.numof); | ||
| } | ||
| #if ENABLE_DEBUG && MODULE_OD | ||
| DEBUG("Received SPI data (%u bytes):\n", (unsigned)_spi_size); | ||
| od_hex_dump(_spi_buf, _spi_size, sizeof(ws281x_spi_data_t)); | ||
| #endif | ||
| } | ||
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| static void _ws281x_write_buffer_unaligned(const void *_buf, size_t size) | ||
| { | ||
| const uint8_t *buf = _buf; | ||
| uint8_t *out = _spi_buf + _spi_size; | ||
| size_t bit_pos = 0; | ||
| for (size_t i = 0; i < size; i++) { | ||
| uint8_t byte = buf[i]; | ||
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| for (int b = 7; b >= 0; b--) { | ||
| uint8_t nibble = (byte & (1u << b)) ? WS281X_SPI_NIBBLE_1 | ||
| : WS281X_SPI_NIBBLE_0; | ||
| /* Pack _SPI_BITS_PER_WS bits into _spi_buf */ | ||
| for (int k = WS281X_SPI_BITS_PER_WS_BIT - 1; k >= 0; k--) { | ||
| size_t byte_index = bit_pos / 8; | ||
| size_t bit_index = 7 - (bit_pos % 8); | ||
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| if (nibble & (1u << k)) { | ||
| out[byte_index] |= (1u << bit_index); | ||
| } | ||
| else { | ||
| out[byte_index] &= ~(1u << bit_index); | ||
| } | ||
| bit_pos++; | ||
| } | ||
| } | ||
| } | ||
| _spi_size += (bit_pos + 7) / 8; | ||
| } | ||
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| static void _ws281x_write_buffer_aligned(const void *_buf, size_t size) | ||
| { | ||
| const uint8_t *buf = _buf; | ||
| uint8_t *out = _spi_buf + _spi_size; | ||
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| const unsigned ws_bits_per_spi_byte = 8 / WS281X_SPI_BITS_PER_WS_BIT; | ||
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| for (size_t i = 0; i < size; i++) { | ||
| uint8_t byte = buf[i]; | ||
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| /* Encode multiple WS bits per SPI byte */ | ||
| for (unsigned bit = 0; bit < 8; bit += ws_bits_per_spi_byte) { | ||
| uint8_t spi_byte = 0; | ||
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| for (unsigned j = 0; j < ws_bits_per_spi_byte; j++) { | ||
| spi_byte <<= WS281X_SPI_BITS_PER_WS_BIT; | ||
| spi_byte |= (byte & 0x80) ? WS281X_SPI_NIBBLE_1 : WS281X_SPI_NIBBLE_0; | ||
| byte <<= 1; | ||
| } | ||
| *out++ = spi_byte; | ||
| } | ||
| } | ||
| _spi_size = out - _spi_buf; | ||
| } | ||
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| void ws281x_write_buffer(ws281x_t *dev, const void *_buf, size_t size) | ||
| { | ||
| assert(dev); | ||
| assert(size % WS281X_BYTES_PER_DEVICE == 0); | ||
| assert(size * WS281X_SPI_BITS_PER_WS_BIT <= sizeof(_spi_buf)); | ||
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| if (8 % WS281X_SPI_BITS_PER_WS_BIT) { | ||
| _ws281x_write_buffer_unaligned(_buf, size); | ||
| } | ||
| else { | ||
| _ws281x_write_buffer_aligned(_buf, size); | ||
| } | ||
| } | ||
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