Working on a sort of secret-santa gift for members of my truck club, I decided to do something with the WS2812B RGB LED’s. There’s a metric buttload of blog articles about these so I thought I would try to add something.<\/p>\n
From what I can see, people are spending a lot of time dealing with timing. Nodemcu can do it but not if WIFI is enabled; or at least reliably anyway.. Since I’d had some success with the hardware SPI on the ESP8266 talking to a thermocouple amplifier, I thought I would try to get the SPI hardware to do my bitbanging for me. Turns out it’s actually quite trivial and ‘just worked’. Thanks to Joost Damad<\/a> for the pattern which saved me the effort of figuring it out myself. Isn’t the internet amazing? Whenever you get a bright idea, turns out someone’s already done it.<\/p>\n First initialize the hardware SPI interface per David Ogilvy’s blog<\/a>:<\/p>\n Then simply load the bit in question into the SPI data register:<\/p>\n and that’s it. To send an RGB sequence for a single LED:<\/p>\n I haven’t really put any effort into optimizing this. I suppose it might be possible to pre-generate a pattern and blow the whole thing out the SPI but I wasn’t in the mood. What I’ve got works fairly well.<\/p>\n Here it is in action<\/a><\/p>\n Code is available here<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" Working on a sort of secret-santa gift for members of my truck club, I decided to do something with the WS2812B RGB LED’s. There’s a metric buttload of blog articles about these so I thought I would try to add something. From what I can see, people are spending a lot of time dealing with… Continue reading »<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-48","post","type-post","status-publish","format-standard","hentry","category-tech-stuff"],"_links":{"self":[{"href":"https:\/\/www.beer.org\/blog\/index.php\/wp-json\/wp\/v2\/posts\/48","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.beer.org\/blog\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.beer.org\/blog\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.beer.org\/blog\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.beer.org\/blog\/index.php\/wp-json\/wp\/v2\/comments?post=48"}],"version-history":[{"count":1,"href":"https:\/\/www.beer.org\/blog\/index.php\/wp-json\/wp\/v2\/posts\/48\/revisions"}],"predecessor-version":[{"id":49,"href":"https:\/\/www.beer.org\/blog\/index.php\/wp-json\/wp\/v2\/posts\/48\/revisions\/49"}],"wp:attachment":[{"href":"https:\/\/www.beer.org\/blog\/index.php\/wp-json\/wp\/v2\/media?parent=48"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.beer.org\/blog\/index.php\/wp-json\/wp\/v2\/categories?post=48"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.beer.org\/blog\/index.php\/wp-json\/wp\/v2\/tags?post=48"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}bool\r\nICACHE_FLASH_ATTR\r\nws2812b_init(void)\r\n{\r\n if (initialized || sysCfg.board_id != BOARD_ID_PHROB_WS2812B)\r\n return true;\r\n spi_init_gpio(SPI_DEV, SPI_CLK_USE_DIV);\r\n spi_clock(SPI_DEV, SPI_CLK_PREDIV, SPI_CLK_CNTDIV);\r\n spi_tx_byte_order(SPI_DEV, SPI_BYTE_ORDER_HIGH_TO_LOW);\r\n spi_rx_byte_order(SPI_DEV, SPI_BYTE_ORDER_HIGH_TO_LOW);\r\n SET_PERI_REG_MASK(SPI_USER(SPI_DEV), SPI_CS_SETUP|SPI_CS_HOLD);\r\n CLEAR_PERI_REG_MASK(SPI_USER(SPI_DEV), SPI_FLASH_MODE);\r\n initialized = 1;\r\n pcfg.stringlen = 16;\r\n pcfg.ms_delay = 500;\r\n os_timer_setfn(&PatternTimer, PatternTimerHandler, NULL);\r\n return true;\r\n}\r\n<\/pre>\nws2812b_send_zero(void)\r\n{\r\n\r\n int xtemp;\r\n xtemp = spi_transaction(1, 8, 0x80, 0, 0, 0, 0, 0, 0);\r\n}\r\n\r\nws2812b_send_one(void)\r\n{\r\n int xtemp;\r\n xtemp = spi_transaction(1, 8, 0xe0, 0, 0, 0, 0, 0, 0);\r\n}\r\n<\/pre>\nstatic inline void\r\nws2812b_send_color(uint8_t c)\r\n{\r\n uint8_t bit=0x80;\r\n while(bit) {\r\n if (c&bit)\r\n ws2812b_send_one();\r\n else\r\n ws2812b_send_zero();\r\n bit>>=1;\r\n }\r\n}\r\n\r\nvoid\r\nws2812b_send_rgb(uint8_t r, uint8_t g, uint8_t b)\r\n{\r\n ws2812b_send_color(g);\r\n ws2812b_send_color(r);\r\n ws2812b_send_color(b);\r\n}\r\n<\/pre>\n