From 2d2ee8d1f0cf3155cb561d59b028f2d2cc40103c Mon Sep 17 00:00:00 2001
From: Mihai Tudor Panu <mihai.tudor.panu@intel.com>
Date: Thu, 25 Aug 2016 17:33:41 -0700
Subject: [PATCH] apa102: added extra functionality

Exposed call to MRAA SPI frequency for those super long strips where the clock signal will degrade and introduce glitches. Slowing down will fix it without the need for extra filtering or redrivers. Batch mode also helps since only one write per frame will be required.

Added functions that control brightness only for fade effects without the need to keep an extra copy of the pixel color map.

Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>
---
 src/apa102/apa102.cxx | 30 ++++++++++++++++++++++++++++++
 src/apa102/apa102.hpp | 35 +++++++++++++++++++++++++++++++----
 2 files changed, 61 insertions(+), 4 deletions(-)

diff --git a/src/apa102/apa102.cxx b/src/apa102/apa102.cxx
index a43004a9..264c7418 100644
--- a/src/apa102/apa102.cxx
+++ b/src/apa102/apa102.cxx
@@ -96,6 +96,12 @@ APA102::setLed(uint16_t ledIdx, uint8_t brightness, uint8_t r, uint8_t g, uint8_
     setLeds(ledIdx, ledIdx, brightness, r, g, b);
 }
 
+void
+APA102::setLedBrightness(uint16_t ledIdx, uint8_t brightness)
+{
+    setLedsBrightness(ledIdx, ledIdx, brightness);
+}
+
 void
 APA102::setAllLeds(uint8_t brightness, uint8_t r, uint8_t g, uint8_t b)
 {
@@ -120,6 +126,21 @@ APA102::setLeds(uint16_t startIdx, uint16_t endIdx, uint8_t brightness, uint8_t
     }
 }
 
+void
+APA102::setLedsBrightness(uint16_t startIdx, uint16_t endIdx, uint8_t brightness)
+{
+    uint16_t s_idx = (startIdx + 1) * 4;
+    uint16_t e_idx = (endIdx + 1) * 4;
+
+    for (uint16_t i = s_idx; i <= e_idx; i += 4) {
+        m_leds[i] = brightness | 224;
+    }
+
+    if (!m_batchMode) {
+        pushState();
+    }
+}
+
 void
 APA102::setLeds(uint16_t startIdx, uint16_t endIdx, uint8_t* colors)
 {
@@ -131,6 +152,15 @@ APA102::setLeds(uint16_t startIdx, uint16_t endIdx, uint8_t* colors)
     }
 }
 
+void
+APA102::setBusSpeed(int hz)
+{
+    if (m_spi->frequency(hz) != mraa::SUCCESS) {
+        throw std::runtime_error(std::string(__FUNCTION__) +
+                                    ": Failed to change SPI bus speed");
+    }
+}
+
 void
 APA102::pushState(void)
 {
diff --git a/src/apa102/apa102.hpp b/src/apa102/apa102.hpp
index 34033e8b..24437306 100644
--- a/src/apa102/apa102.hpp
+++ b/src/apa102/apa102.hpp
@@ -74,7 +74,7 @@ class APA102
     ~APA102();
 
     /**
-     * Change the color for a single led
+     * Change the color and brightness for a single led
      *
      * @param ledIdx        Index of the LED in the strip (0 based)
      * @param brightness    Brightness value (0-31)
@@ -85,7 +85,15 @@ class APA102
     void setLed(uint16_t ledIdx, uint8_t brightness, uint8_t r, uint8_t g, uint8_t b);
 
     /**
-     * Change the color for all leds
+     * Change the brightness for a single led
+     *
+     * @param ledIdx        Index of the LED in the strip (0 based)
+     * @param brightness    Brightness value (0-31)
+     */
+    void setLedBrightness(uint16_t ledIdx, uint8_t brightness);
+
+    /**
+     * Change the color and brightness for all leds
      *
      * @param brightness    Brightness value (0-31)
      * @param r             Red component (0-255)
@@ -95,7 +103,7 @@ class APA102
     void setAllLeds(uint8_t brightness, uint8_t r, uint8_t g, uint8_t b);
 
     /**
-     * Change the color for a range of leds
+     * Change the color and brightness for a range of leds
      *
      * @param startIdx      Start index of the range of LEDs in the strip (0 based)
      * @param endIdx        End index of the range of LEDs in the strip (0 based)
@@ -108,7 +116,17 @@ class APA102
     setLeds(uint16_t startIdx, uint16_t endIdx, uint8_t brightness, uint8_t r, uint8_t g, uint8_t b);
 
     /**
-     * (Advanced) Manually control the colors of a range of LEDS
+     * Change the brightness for a range of leds
+     *
+     * @param startIdx      Start index of the range of LEDs in the strip (0 based)
+     * @param endIdx        End index of the range of LEDs in the strip (0 based)
+     * @param brightness    Brightness value (0-31)
+     */
+    void
+    setLedsBrightness(uint16_t startIdx, uint16_t endIdx, uint8_t brightness);
+
+    /**
+     * (Advanced) Manually control the colors and brightness of a range of LEDS
      * Best used to maximize performance
      *
      * @param startIdx      Start index of the range of LEDs to update (0 based)
@@ -120,6 +138,15 @@ class APA102
      */
     void setLeds(uint16_t startIdx, uint16_t endIdx, uint8_t* colors);
 
+    /**
+     * Change the speed/frequency of the SPI bus
+     * Note: Slower speeds will allow driving longer strips without having to
+     * condition the clock signal with extra hardware
+     *
+     * @param hz    Desired bus speed in Hz
+     */
+    void setBusSpeed(int hz);
+
     /**
      * Outputs the current LED data to the SPI bus
      * Note: Only required if batch mode is set to TRUE