#include "LedDeviceSk6822SPI.h" /* From the data sheet: (TH+TL=1.7μs±600ns) T0H, 0 code, high level time, 0.35µs ±0.150ns T0L, 0 code, low level time, 1.36µs ±0.150ns T1H, 1 code, high level time, 1.36µs ±0.150ns T1L, 1 code, low level time, 0.35µs ±0.150ns WT, Wait for the processing time, 12µs ±0.150ns Trst, Reset code,low level time, 50µs To normalise the pulse times so they fit in 4 SPI bits: Use timings at upper end of tolerance: 1.36 -> 1.50 uS 0.35 -> 0.50 uS A SPI bit time of 0.50uS = 2Mbit/sec T0 is sent as 1000 T1 is sent as 1110 With a bit of excel testing, we can work out the maximum and minimum speeds: 2000000 MIN 2230000 AVG 2460000 MAX Wait time: using the min of 2000000, the bit time is 0.500 Wait time is 12uS = 24 bits = 3 bytes Reset time: using the min of 2000000, the bit time is 0.500 Reset time is 50uS = 100 bits = 13 bytes */ LedDeviceSk6822SPI::LedDeviceSk6822SPI(const QJsonObject &deviceConfig) : ProviderSpi() , SPI_BYTES_PER_COLOUR(4) , SPI_BYTES_WAIT_TIME(3) , SPI_FRAME_END_LATCH_BYTES(13) , bitpair_to_byte { 0b10001000, 0b10001110, 0b11101000, 0b11101110, } { _devConfig = deviceConfig; _deviceReady = false; } LedDevice* LedDeviceSk6822SPI::construct(const QJsonObject &deviceConfig) { return new LedDeviceSk6822SPI(deviceConfig); } bool LedDeviceSk6822SPI::init(const QJsonObject &deviceConfig) { _baudRate_Hz = 2230000; bool isInitOK = ProviderSpi::init(deviceConfig); if ( isInitOK ) { WarningIf(( _baudRate_Hz < 2000000 || _baudRate_Hz > 2460000 ), _log, "SPI rate %d outside recommended range (2000000 -> 2460000)", _baudRate_Hz); _ledBuffer.resize( (_ledRGBCount * SPI_BYTES_PER_COLOUR) + (_ledCount * SPI_BYTES_WAIT_TIME ) + SPI_FRAME_END_LATCH_BYTES, 0x00); // Debug(_log, "_ledBuffer.resize(_ledRGBCount:%d * SPI_BYTES_PER_COLOUR:%d) + ( _ledCount:%d * SPI_BYTES_WAIT_TIME:%d ) + SPI_FRAME_END_LATCH_BYTES:%d, 0x00)", _ledRGBCount, SPI_BYTES_PER_COLOUR, _ledCount, SPI_BYTES_WAIT_TIME, SPI_FRAME_END_LATCH_BYTES); } return isInitOK; } int LedDeviceSk6822SPI::write(const std::vector &ledValues) { unsigned spi_ptr = 0; const int SPI_BYTES_PER_LED = sizeof(ColorRgb) * SPI_BYTES_PER_COLOUR; for (const ColorRgb& color : ledValues) { uint32_t colorBits = ((unsigned int)color.red << 16) | ((unsigned int)color.green << 8) | color.blue; for (int j=SPI_BYTES_PER_LED - 1; j>=0; j--) { _ledBuffer[spi_ptr+j] = bitpair_to_byte[ colorBits & 0x3 ]; colorBits >>= 2; } spi_ptr += SPI_BYTES_PER_LED; spi_ptr += SPI_BYTES_WAIT_TIME; // the wait between led time is all zeros } /* // debug the whole SPI packet char debug_line[2048]; int ptr=0; for (unsigned int i=0; i < _ledBuffer.size(); i++) { if (i%16 == 0) { ptr += snprintf (ptr+debug_line, sizeof(debug_line)-ptr, "%03x: ", i); } ptr += snprintf (ptr+debug_line, sizeof(debug_line)-ptr, "%02x ", _ledBuffer.data()[i]); if ( (i%16 == 15) || ( i == _ledBuffer.size()-1 ) ) { Debug(_log, debug_line); ptr = 0; } } */ return writeBytes(_ledBuffer.size(), _ledBuffer.data()); }