driver for WS2812B LED, modified for better compatibility with LPC812 and LPC1549
Fork of wsDrive by
wsDrive.h
- Committer:
- JojoS
- Date:
- 2016-12-10
- Revision:
- 6:270a9728ee29
- Parent:
- 3:3c48065d20ff
File content as of revision 6:270a9728ee29:
#ifndef __wsDrive_h__ #define __wsDrive_h__ #include "BurstSPI.h" /**************************************************************** * An alternative WS2811/2812 driver using the BusrtSPI library * Credit for the inspiration goes to Jacob for his pixelArray library * http://developer.mbed.org/users/JacobBramley/code/PixelArray/ * * This version was written mainly to help me understand what was going on * While the end result is the same the code is completely from scratch. * *****************************************************************/ /** A structure used to hold a single pixel or a pixel colour * * Each colour can be set to any value between about -32,768 and +32,767 (the 16 bit signed number range) * 0 or negative values mean that colour is off, 255 or more mean on at full brightness. * In between means partially on. * If you are never going to go outside the 0-255 range then use pixelInfo, it uses half the memory. * however if you are calculating pixel values when superimposing two images and don't want to worry about wrap around then use this version. * * Note, lots of LEDs on bright will use a lot of power, make sure your supply can cope. * * @param G The green component * @param R The red component * @param B The blue component */ typedef struct pixelInfo16 { int16_t G; int16_t R; int16_t B; } pixelInfo16; /** A structure used to hold a single pixel or a pixel colour * * Each colour can be set to any value between 0 and 255. * 0 = off, 255 = full brightness. * * Note, lots of LEDs on bright will use a lot of power, make sure your supply can cope. * * @param G The green component * @param R The red component * @param B The blue component */ typedef struct pixelInfo { unsigned char G; unsigned char R; unsigned char B; } pixelInfo; /** Drives a WS2812 LED chain * * An alternative WS2811/2812 driver using the BusrtSPI library * * Credit for the inspiration goes to Jacob for his pixelArray library * http://developer.mbed.org/users/JacobBramley/code/PixelArray/ * * This version was written mainly to help me understand what was going on and is a little more basic. * While the end result is muc the same the code is completely from scratch. * * BurstSPI is used to generate the timing so support is limited to the parts supported by that library. * * Also note that while all 3 SPI pins are specified only the MOSI pin is actually needed and should connect to the data in on the LEDs * * Values for each LED are stored in either an array of pixelInfo or pixelInfo16 structures * Each LED only supports 0-255 for each colour, the limits of the pixelInfo data type. * * The 16 bit version is for when you are adding/subtracting values in order to avoid * wraparound issues. When displayed the values outside the range are clamped to the limits. * This allows tricks like having a point with negative brighnesses moving along the line to add a * dark spot without having to worry about what happens if a number goes negative. * * * Example code to run a single lit led along a chain * * @code * * #include "mbed.h" * #include "wsDrive.h" * * // update period in ms * #define updatePeriod 100 * // number of LEDs * #define chainLen 8 * * DigitalIn dummy(MOSI,PullDown); // first activate the pulldown on the pin. * wsDrive ledDriver(MOSI,MISO,CLK); // create the SPI bus. You can normally list the MISO and CLK as NC but some mbed library versions don't like that * * // pixel storage buffer * pixelInfo pixelData[chainLen]; * * Timer updateRateTimer; * * void blankBuffer(pixelInfo *Ptr) * { * memset( (void *)Ptr, 0, chainLen*sizeof(pixelInfo) ); * } * * void setPixel(unsigned int index, pixelInfo *colourToUse) { * if (index < chainLen) { * pixelData[index].R = colourToUse->R; * pixelData[index].G = colourToUse->G; * pixelData[index].B = colourToUse->B; * } * } * * void clearPixel(unsigned int index) { * if (index < chainLen) { * pixelData[index].R = 0; * pixelData[index].G = 0; * pixelData[index].B = 0; * } * } * * int main () { * * int litLed = 0; * * pixelInfo colour; * colour.R = 0x80; * colour.G = 0x00; * colour.B = 0x00; * * // Tell the driver where the data is stored * ledDriver.setData(pixelData, chainLen); * * // Set the buffer to the pattern we want * blankBuffer(pixelData); * setPixel(litLed, &colour); * * updateRateTimer.start(); * while (true) { * * ledDriver.sendData(); // send the LED data * * // modify the buffer ready for the next update * clearPixel(litLed); * litLed++; * if (litLed == chainLen) * litLed = 0; * setPixel(litLed, &colour); * * // wait until the correct time since the last update... * while (updateRateTimer.read_ms() < updatePeriod) { * } * updateRateTimer.reset(); * } * } * @endcode * * Troubleshooting: * * If the LEDs aren't lighting up correctly then check that your power supply is up to the job (or decrease the brightness you are using) * * Also check the supply voltage, on paper when running off 5V the WS2812 needs 4V on the data in pin to detect a high. Mbed based boards rarely output much over 3.1V. * This problem is normally indicated by the very first pattern send on power up being displayed but then no further updates being recieved. Dropping the supply voltage * to about 4.2 - 4.3 V will normally fix this problem without any meaningful impact on the LED output. * */ class wsDrive : private BurstSPI { public: /** create the driver */ wsDrive(PinName mosi, PinName miso, PinName clk); /** Set the data pointer Before data can be sent the driver must be given a pointer to the pixel data to use. Setting this is normally a one time operation unless you want to switch between buffers. Calling this function will replace any prior buffers including pixelInfo16 ones. @param dataStart The start of an array of pixelInfo items. This will be sent to the chain in order. @param dataLen The length of the array. */ void setData(pixelInfo *dataStart, uint16_t dataLen); /** Set the data pointer Before data can be sent the driver must be given a pointer to the pixel data to use. Setting this is normally a one time operation unless you want to switch between buffers. Calling this function will replace any prior buffers including pixelInfo ones. @param dataStart The start of an array of pixelInfo16 items. This will be sent to the chain in order. @param dataLen The length of the array. */ void setData(pixelInfo16 *dataStart, uint16_t dataLen); /** Sends the data to the LEDs * setData() must be called prior to this. */ void sendData(); private: void sendByte(unsigned char value); void sendPixel(pixelInfo *pixToSend); void sendPixel(pixelInfo16 *pixToSend); pixelInfo *pixArray; pixelInfo16 *pixArray16; uint16_t pixelLen; }; #endif