Add per-channel user-settable gamma correction (#171)

* Pi Zero W v1.1 support added to rpihw.c * Update rpihw.c (#164) added raspi Zero W * Device-tree auto-detect * Channel gamma support * Reverted to old detection, added 0x9200c1 * Changed gamma correction to match leds * Removed dead dt detect code * Re added "Pi Zero W v1.1", .hwver = 0x9000c1, (#181) * Added PCM and SPI support. Specifying the corresponding GPIO pin will (#170) select either PWM, PCM or SPI. PCM and SPI only support 1 channel. Increased version to 1.1.0. Updated README.md * Fix setting of brightness in go bindings (#174) Fixes #151 * Added delay to ensure reset time being met with low led counts (#157) * Fix includes as per #178 (#189) * clean up doco and strandtest (#187) * updated documentation on GPIO usage strandtest now defaults to GRB colour order added version.h to gitignore * updated python readme * more README cleanup * added notes on spi max transfer size
jgarff · Jul 6, 2017 · aee7ccc · aee7ccc
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diff --git a/.gitignore b/.gitignore
@@ -1,4 +1,5 @@
 .sconsign.dblite
+version.h
 *.pyc
 test
 newtest

diff --git a/README.md b/README.md
@@ -23,7 +23,36 @@ each bit is represented by 3 bits as follows.
     Bit 0 - 1 0 0
 
 
-### Hardware:
+### GPIO Usage:
+
+The GPIOs that can be used are limited by the hardware of the Pi and will
+vary based on the method used to drive them (PWM, PCM or SPI).
+Beware that the GPIO numbers are not the same as the physical pin numbers
+on the header.
+
+PWM:
+```
+        PWM0, which can be set to use GPIOs 12, 18, 40, and 52.
+        Only 12 (pin 32) and 18 (pin 12) are available on the B+/2B/3B
+
+        PWM1 which can be set to use GPIOs 13, 19, 41, 45 and 53.
+        Only 13 is available on the B+/2B/PiZero/3B, on pin 33
+```
+
+PCM:
+```
+        PCM_DOUT, which can be set to use GPIOs 21 and 31.
+        Only 21 is available on the B+/2B/PiZero/3B, on pin 40.
+```
+
+SPI:
+```
+        SPI0-MOSI is available on GPIOs 10 and 38.
+        Only GPIO 10 is available on all models.
+```
+
+
+### Power and voltage requirements
 
 WS281X LEDs are generally driven at 5V, which requires that the data
 signal be at the same level.  Converting the output from a Raspberry
@@ -52,10 +81,24 @@ reponsibility for damage, harm, or mistakes.
 
 ### Running:
 
-- Type 'sudo scons'.
 - Type 'sudo ./test' (default uses PWM channel 0).
 - That's it.  You should see a moving rainbow scroll across the
   display.
+- More options are available, ./test -h should show them:
+```
+./test version 1.1.0
+Usage: ./test
+-h (--help)    - this information
+-s (--strip)   - strip type - rgb, grb, gbr, rgbw
+-x (--width)   - matrix width (default 8)
+-y (--height)  - matrix height (default 8)
+-d (--dma)     - dma channel to use (default 5)
+-g (--gpio)    - GPIO to use
+                 If omitted, default is 18 (PWM0)
+-i (--invert)  - invert pin output (pulse LOW)
+-c (--clear)   - clear matrix on exit.
+-v (--version) - version information
+```
 
 ### Limitations:
 
@@ -71,6 +114,14 @@ blacklist the Broadcom audio kernel module by creating a file
 If the audio device is still loading after blacklisting, you may also
 need to comment it out in the /etc/modules file.
 
+On headless systems you may also need to force audio through hdmi
+Edit config.txt and add:
+
+    hdmi_force_hotplug=1
+    hdmi_force_edid_audio=1
+
+A reboot is required for this change to take effect
+
 Some distributions use audio by default, even if nothing is being played.
 If audio is needed, you can use a USB audio device instead.
 
@@ -84,10 +135,14 @@ uses the PCM hardware, but you can use analog audio.
 When using SPI the ledstring is the only device which can be connected to
 the SPI bus. Both digital (I2S/PCM) and analog (PWM) audio can be used.
 
+Many distributions have a maximum SPI transfer of 4096 bytes. This can be
+changed in /boot/config.txt
+    spidev.bufsiz=32768
+
 ### Comparison PWM/PCM/SPI
 
 Both PWM and PCM use DMA transfer to output the control signal for the LEDs.
-The max size of a DMA transfer is 65536 bytes. SInce each LED needs 12 bytes
+The max size of a DMA transfer is 65536 bytes. Since each LED needs 12 bytes
 (4 colors, 8 symbols per color, 3 bits per symbol) this means you can
 control approximately 5400 LEDs for a single strand in PCM and 2700 LEDs per string
 for PWM (Only PWM can control 2 independent strings simultaneously)

diff --git a/golang/ws2811/ws2811.go b/golang/ws2811/ws2811.go
@@ -47,7 +47,7 @@ import (
 func Init(gpioPin int, ledCount int, brightness int) error {
 	C.ledstring.channel[0].gpionum = C.int(gpioPin)
 	C.ledstring.channel[0].count = C.int(ledCount)
-	C.ledstring.channel[0].brightness = C.int(brightness)
+	C.ledstring.channel[0].brightness = C.uint8_t(brightness)
 	res := int(C.ws2811_init(&C.ledstring))
 	if res == 0 {
 		return nil

diff --git a/mailbox.c b/mailbox.c
@@ -37,7 +37,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <unistd.h>
 #include <sys/mman.h>
 #include <sys/ioctl.h>
-#include <sys/types.h>
+#include <sys/sysmacros.h>
 #include <sys/stat.h>
 
 #include "mailbox.h"

diff --git a/main.c b/main.c
@@ -265,7 +265,7 @@ void parseargs(int argc, char **argv, ws2811_t *ws2811)
 	PWM0, which can be set to use GPIOs 12, 18, 40, and 52. 
 	Only 12 (pin 32) and 18 (pin 12) are available on the B+/2B/3B
 	PWM1 which can be set to use GPIOs 13, 19, 41, 45 and 53. 
-	Only 13 is available on the B+/2B/PiZero/3B, on pin 35
+	Only 13 is available on the B+/2B/PiZero/3B, on pin 33
 	PCM_DOUT, which can be set to use GPIOs 21 and 31.
 	Only 21 is available on the B+/2B/PiZero/3B, on pin 40.
 	SPI0-MOSI is available on GPIOs 10 and 38.

diff --git a/python/README.md b/python/README.md
@@ -1,10 +1,19 @@
 # Build
 
+As this is just a python wrapper for the library you must first follow
+the build instructions in the parent directory.
+When complete, you can build this python wrapper:
 ```
   sudo apt-get install python-dev swig
   python ./setup.py build
 ```
 
+If you are rebuilding after fetching some updated commits, you might need to
+remove the build directory first
+```
+  rm -rf ./build
+```
+
 # Run a demo
 
 ```

diff --git a/python/examples/strandtest.py b/python/examples/strandtest.py
@@ -10,11 +10,15 @@
 
 # LED strip configuration:
 LED_COUNT      = 16      # Number of LED pixels.
-LED_PIN        = 18      # GPIO pin connected to the pixels (must support PWM!).
+LED_PIN        = 18      # GPIO pin connected to the pixels (18 uses PWM!).
+#LED_PIN        = 10      # GPIO pin connected to the pixels (10 uses SPI /dev/spidev0.0).
 LED_FREQ_HZ    = 800000  # LED signal frequency in hertz (usually 800khz)
 LED_DMA        = 5       # DMA channel to use for generating signal (try 5)
 LED_BRIGHTNESS = 255     # Set to 0 for darkest and 255 for brightest
 LED_INVERT     = False   # True to invert the signal (when using NPN transistor level shift)
+LED_CHANNEL    = 0       # set to '1' for GPIOs 13, 19, 41, 45 or 53
+LED_STRIP      = ws.WS2811_STRIP_GRB   # Strip type and colour ordering
+
 
 
 # Define functions which animate LEDs in various ways.
@@ -78,21 +82,21 @@ def theaterChaseRainbow(strip, wait_ms=50):
 # Main program logic follows:
 if __name__ == '__main__':
 	# Create NeoPixel object with appropriate configuration.
-	strip = Adafruit_NeoPixel(LED_COUNT, LED_PIN, LED_FREQ_HZ, LED_DMA, LED_INVERT, LED_BRIGHTNESS)
+	strip = Adafruit_NeoPixel(LED_COUNT, LED_PIN, LED_FREQ_HZ, LED_DMA, LED_INVERT, LED_BRIGHTNESS, LED_CHANNEL, LED_STRIP)
 	# Intialize the library (must be called once before other functions).
 	strip.begin()
 
 	print ('Press Ctrl-C to quit.')
 	while True:
-		# Color wipe animations.
+		print ('Color wipe animations.')
 		colorWipe(strip, Color(255, 0, 0))  # Red wipe
 		colorWipe(strip, Color(0, 255, 0))  # Blue wipe
 		colorWipe(strip, Color(0, 0, 255))  # Green wipe
-		# Theater chase animations.
+		print ('Theater chase animations.')
 		theaterChase(strip, Color(127, 127, 127))  # White theater chase
 		theaterChase(strip, Color(127,   0,   0))  # Red theater chase
 		theaterChase(strip, Color(  0,   0, 127))  # Blue theater chase
-		# Rainbow animations.
+		print ('Rainbow animations.')
 		rainbow(strip)
 		rainbowCycle(strip)
 		theaterChaseRainbow(strip)
diff --git a/rpihw.c b/rpihw.c
@@ -210,6 +210,20 @@ static const rpi_hw_t rpi_hw_info[] = {
         .videocore_base = VIDEOCORE_BASE_RPI,
         .desc = "Pi Zero v1.3",
     },
+    {
+        .hwver  = 0x9000c1,
+        .type = RPI_HWVER_TYPE_PI1,
+        .periph_base = PERIPH_BASE_RPI,
+        .videocore_base = VIDEOCORE_BASE_RPI,
+        .desc = "Pi Zero W v1.1",
+    },
+    {
+        .hwver  = 0x9200c1,
+        .type = RPI_HWVER_TYPE_PI1,
+        .periph_base = PERIPH_BASE_RPI,
+        .videocore_base = VIDEOCORE_BASE_RPI,
+        .desc = "Pi Zero W v1.1",
+    },
 
     //
     // Model A+
@@ -293,7 +307,6 @@ static const rpi_hw_t rpi_hw_info[] = {
 
 };
 
-
 const rpi_hw_t *rpi_hw_detect(void)
 {
     FILE *f = fopen("/proc/cpuinfo", "r");

diff --git a/ws2811.c b/ws2811.c
@@ -33,14 +33,14 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <signal.h>
 #include <linux/types.h>
 #include <linux/spi/spidev.h>
+#include <time.h>
 
 #include "mailbox.h"
 #include "clk.h"
@@ -63,6 +63,9 @@
 #define LED_BIT_COUNT(leds, freq)                ((leds * LED_COLOURS * 8 * 3) + ((LED_RESET_uS * \
                                                   (freq * 3)) / 1000000))
 
+/* Minimum time to wait for reset to occur in microseconds. */
+#define LED_RESET_WAIT_TIME                      300
+
 // Pad out to the nearest uint32 + 32-bits for idle low/high times the number of channels
 #define PWM_BYTE_COUNT(leds, freq)               (((((LED_BIT_COUNT(leds, freq) >> 3) & ~0x7) + 4) + 4) * \
                                                   RPI_PWM_CHANNELS)
@@ -111,6 +114,22 @@ typedef struct ws2811_device
     int max_count;
 } ws2811_device_t;
 
+/**
+ * Provides monotonic timestamp in microseconds.
+ *
+ * @returns  Current timestamp in microseconds or 0 on error.
+ */
+static uint64_t get_microsecond_timestamp()
+{
+    struct timespec t;
+
+    if (clock_gettime(CLOCK_MONOTONIC_RAW, &t) != 0) {
+        return 0;
+    }
+
+    return t.tv_sec * 1000000 + t.tv_nsec / 1000;
+}
+
 /**
  * Iterate through the channels and find the largest led count.
  *
@@ -590,6 +609,11 @@ void ws2811_cleanup(ws2811_t *ws2811)
             free(ws2811->channel[chan].leds);
         }
         ws2811->channel[chan].leds = NULL;
+        if (ws2811->channel && ws2811->channel[chan].gamma)
+        {
+            free(ws2811->channel[chan].gamma);
+        }
+        ws2811->channel[chan].gamma = NULL;
     }
 
     if (device->mbox.handle != -1)
@@ -929,6 +953,13 @@ ws2811_return_t ws2811_init(ws2811_t *ws2811)
           channel->strip_type=WS2811_STRIP_RGB;
         }
 
+        // Set default uncorrected gamma table
+        channel->gamma = malloc(sizeof(uint8_t) * 256);
+        int x;
+        for(x = 0; x < 256; x++){
+          channel->gamma[x] = x;
+        }
+
         channel->wshift = (channel->strip_type >> 24) & 0xff;
         channel->rshift = (channel->strip_type >> 16) & 0xff;
         channel->gshift = (channel->strip_type >> 8)  & 0xff;
@@ -1067,33 +1098,43 @@ ws2811_return_t  ws2811_render(ws2811_t *ws2811)
     int i, k, l, chan;
     unsigned j;
     ws2811_return_t ret = WS2811_SUCCESS;
+    uint32_t protocol_time = 0;
 
     bitpos = (driver_mode == SPI ? 7 : 31);
 
     for (chan = 0; chan < RPI_PWM_CHANNELS; chan++)         // Channel
     {
         ws2811_channel_t *channel = &ws2811->channel[chan];
+
         int wordpos = chan; // PWM & PCM
         int bytepos = 0;    // SPI
-        const int scale   = (channel->brightness & 0xff) + 1;
+        const int scale = (channel->brightness & 0xff) + 1;
+        uint8_t array_size = 3; // Assume 3 color LEDs, RGB
+
+        // 1.25µs per bit
+        const uint32_t channel_protocol_time = channel->count * array_size * 8 * 1.25;
+
+        // If our shift mask includes the highest nibble, then we have 4 LEDs, RBGW.
+        if (channel->strip_type & SK6812_SHIFT_WMASK)
+        {
+            array_size = 4;
+        }
+
+        // Only using the channel which takes the longest as both run in parallel
+        if (channel_protocol_time > protocol_time)
+        {
+            protocol_time = channel_protocol_time;
+        }
 
         for (i = 0; i < channel->count; i++)                // Led
         {
             uint8_t color[] =
             {
-                (((channel->leds[i] >> channel->rshift) & 0xff) * scale) >> 8, // red
-                (((channel->leds[i] >> channel->gshift) & 0xff) * scale) >> 8, // green
-                (((channel->leds[i] >> channel->bshift) & 0xff) * scale) >> 8, // blue
-                (((channel->leds[i] >> channel->wshift) & 0xff) * scale) >> 8, // white
+                channel->gamma[(((channel->leds[i] >> channel->rshift) & 0xff) * scale) >> 8], // red
+                channel->gamma[(((channel->leds[i] >> channel->gshift) & 0xff) * scale) >> 8], // green
+                channel->gamma[(((channel->leds[i] >> channel->bshift) & 0xff) * scale) >> 8], // blue
+                channel->gamma[(((channel->leds[i] >> channel->wshift) & 0xff) * scale) >> 8], // white
             };
-            uint8_t array_size = 3; // Assume 3 color LEDs, RGB
-
-            // If our shift mask includes the highest nibble, then we have 4
-            // LEDs, RBGW.
-            if (channel->strip_type & SK6812_SHIFT_WMASK)
-            {
-                array_size = 4;
-            }
 
             for (j = 0; j < array_size; j++)               // Color
             {
@@ -1158,15 +1199,26 @@ ws2811_return_t  ws2811_render(ws2811_t *ws2811)
         return ret;
     }
 
+    if (ws2811->render_wait_until != 0) {
+        const uint64_t current_timestamp = get_microsecond_timestamp();
+
+        if (ws2811->render_wait_until > current_timestamp) {
+            usleep(ws2811->render_wait_until - current_timestamp);
+        }
+    }
+
     if (driver_mode != SPI)
     {
         dma_start(ws2811);
     }
-    else if ((ret = spi_transfer(ws2811)) != WS2811_SUCCESS)
+    else
     {
-        return ret;
+        ret = spi_transfer(ws2811);
     }
 
+    // LED_RESET_WAIT_TIME is added to allow enough time for the reset to occur.
+    ws2811->render_wait_until = get_microsecond_timestamp() + protocol_time + LED_RESET_WAIT_TIME;
+
     return ret;
 }