Minor updates

examples/3_FM6126Panel/3_FM6126Panel.ino

@@ -0,0 +1,102 @@
+// How to use this library with a FM6126 panel, thanks goes to:
+// https://github.com/hzeller/rpi-rgb-led-matrix/issues/746
+
+#include <Arduino.h>
+#include <ESP32-HUB75-MatrixPanel-I2S-DMA.h>
+#include <FastLED.h>
+
+////////////////////////////////////////////////////////////////////
+// FM6126 support is still experimental
+
+// Output resolution and panel chain length configuration
+#define PANEL_RES_X 64 	   // Number of pixels wide of each INDIVIDUAL panel module. 
+#define PANEL_RES_Y 32 	   // Number of pixels tall of each INDIVIDUAL panel module.
+#define PANEL_CHAIN 1      // Total number of panels chained one to another
+
+
+// placeholder for the matrix object
+MatrixPanel_I2S_DMA *dma_display = nullptr;
+
+///////////////////////////////////////////////////////////////
+
+// FastLED variables for pattern output
+uint16_t time_counter = 0, cycles = 0, fps = 0;
+unsigned long fps_timer;
+
+CRGB currentColor;
+CRGBPalette16 palettes[] = {HeatColors_p, LavaColors_p, RainbowColors_p, RainbowStripeColors_p, CloudColors_p};
+CRGBPalette16 currentPalette = palettes[0];
+
+
+CRGB ColorFromCurrentPalette(uint8_t index = 0, uint8_t brightness = 255, TBlendType blendType = LINEARBLEND) {
+  return ColorFromPalette(currentPalette, index, brightness, blendType);
+}
+
+void setup(){
+	
+	/*
+		The configuration for MatrixPanel_I2S_DMA object is held in HUB75_I2S_CFG structure,
+		All options has it's predefined default values. So we can create a new structure and redefine only the options we need
+
+		Please refer to the '2_PatternPlasma.ino' example for detailed example of how to use the MatrixPanel_I2S_DMA configuration
+		if you need to change the pin mappings etc.
+	*/
+
+	HUB75_I2S_CFG mxconfig(
+				PANEL_RES_X,   // module width
+				PANEL_RES_Y,   // module height
+				PANEL_CHAIN    // Chain length
+	);
+
+	mxconfig.driver = HUB75_I2S_CFG::FM6126A;     // in case that we use panels based on FM6126A chip, we can set it here before creating MatrixPanel_I2S_DMA object
+
+	// OK, now we can create our matrix object
+	dma_display = new MatrixPanel_I2S_DMA(mxconfig);
+	
+    // If you experience ghosting, you will need to reduce the brightness level, not all RGB Matrix
+    // Panels are the same - some seem to display ghosting artefacts at lower brightness levels.
+    // In the setup() function do something like:
+
+    // let's adjust default brightness to about 75%
+    dma_display->setBrightness8(192);    // range is 0-255, 0 - 0%, 255 - 100%
+	
+    // Allocate memory and start DMA display
+    if( not dma_display->begin() )
+      Serial.println("****** !KABOOM! Insufficient memory - allocation failed ***********");	
+	
+    fps_timer = millis();
+	
+}
+
+void loop(){
+   for (int x = 0; x <  dma_display->width(); x++) {
+        for (int y = 0; y <  dma_display->height(); y++) {
+            int16_t v = 0;
+            uint8_t wibble = sin8(time_counter);
+            v += sin16(x * wibble * 3 + time_counter);
+            v += cos16(y * (128 - wibble)  + time_counter);
+            v += sin16(y * x * cos8(-time_counter) / 8);
+
+            currentColor = ColorFromPalette(currentPalette, (v >> 8) + 127); //, brightness, currentBlendType);
+            dma_display->drawPixelRGB888(x, y, currentColor.r, currentColor.g, currentColor.b);
+        }
+    }
+
+    ++time_counter;
+    ++cycles;
+    ++fps;
+
+    if (cycles >= 1024) {
+        time_counter = 0;
+        cycles = 0;
+        currentPalette = palettes[random(0,sizeof(palettes)/sizeof(palettes[0]))];
+    }
+
+    // print FPS rate every 5 seconds
+    // Note: this is NOT a matrix refresh rate, it's the number of data frames being drawn to the DMA buffer per second
+    if (fps_timer + 5000 < millis()){
+      Serial.printf_P(PSTR("Effect fps: %d\n"), fps/5);
+      fps_timer = millis();
+      fps = 0;
+    }
+}

examples/3_FM6126Panel/FM6126A.md

@@ -0,0 +1,51 @@
+## The mystery of control registers for FM6126A chips
+
+  
+The only available Datasheet for this chips is in Chinese and does not shed a light on what those two control regs are.
+
+An excellent insight could be found here https://github.com/hzeller/rpi-rgb-led-matrix/issues/746#issuecomment-453860510
+
+  
+
+So there are two regs in this chip - **REG1** and **REG2**,
+one could be written with 12 clock pulses (and usually called reg12, dunno why :))
+the other one could be written with 13 clock pulses (and usually called reg13, dunno why :))
+  
+
+I've done some measurements on power consumption while toggling bits of **REG1** and it looks that it could provide a fine grained brightness control over the entire matrix with no need for bitbanging over RGB or EO pins.
+There are 6 bits (6 to 11) giving an increased brightness (compared to all-zeroes) and 4 bits (2-5) giving decreased brightness!!!
+Still unclear if FM6112A brightness control is internally PWMed or current limited, might require some poking with oscilloscope.
+
+So it seems that the most bright (and hungry for power) value is bool REG1[16] = {0,0,0,0,0, 1,1,1,1,1,1, 0,0,0,0,0}; and not {0,1,1,1,1, 1,1,1,1,1,1, 1,1,1,1,1} as it is usually used.
+I'm not sure about bit 1 - it is either not used or I was unable to measure it's influence to brightness/power.
+
+Giving at least 10 bits of hardware brightness control opens pretty nice options for offloading and simplifying matrix output. Should dig into this more deeper.
+
+Here are some of the measurements I've took for 2 64x64 panels filled with white color - reg value and corresponding current drain in amps.
+  
+
+|REG1 |bit value|Current, amps |
+|--|--|--|
+|REG1| 0111111 00000| >5 amps|
+|REG1| 0100010 00000| 3.890 amp|
+|REG1| 0100000 00000| 3.885 amp|
+|REG1| 0011110 00000| 3.640 amp|
+|REG1| 0011100 00000| 3.620 amp|
+|REG1| 0011000 00000| 3.240 amp|
+|REG1| 0010010 00000| 2.520 amp|
+|REG1| 0010001 00000| 2.518 amp|
+|REG1| 0010001 10000| 2.493 amp|
+|REG1| 0010000 00000| 2.490 amp|
+|REG1| 0010000 11110| 2.214 amp|
+|REG1| 0001100 00000| 2.120 amp|
+|REG1| 0001000 00000| 1.750 amp|
+|REG1| 0000100 00000| 1.375 amp|
+|REG1| 0000010 00000| 1.000 amp|
+|REG1| **0000000 00000**| 0.995 amp|
+|REG1| 0000001 11111| 0.700 amp|
+|REG1| 0000000 01111| 0.690 amp|
+|REG1| 0000000 10000| 0.690 amp|
+|REG1| 0000000 11110| 0.686 amp|
+
+
+/Vortigont/

examples/3_FM6126Panel/README.md

@@ -0,0 +1,3 @@
+## FM6126 based LED Matrix Panel Reset ##
+
+FM6216 panels require a special reset sequence before they can be used, check your panel chipset if you have issues. Refer to this example.

src/ESP32-HUB75-MatrixPanel-I2S-DMA.cpp

@@ -24,7 +24,7 @@ bool MatrixPanel_I2S_DMA::allocateDMAmemory()
 
         if (ptr->data == nullptr)
         {
-          ESP_LOGE(TAG, "ERROR: Couldn't malloc rowBitStruct %d! Critical fail.\r\n", malloc_num);
+          ESP_LOGE(TAG, "ERROR: Couldn't malloc rowBitStruct %d! Not enough memory for requested PIXEL_COLOUR_DEPTH_BITS. Please reduce colour depth. Critical fail.\r\n", malloc_num);
                     return false;
               // TODO: should we release all previous rowBitStructs here???
         }

src/ESP32-HUB75-MatrixPanel-I2S-DMA.h

@@ -4,15 +4,14 @@
 /* Core ESP32 hardware / idf includes!                                                 */
 #include <vector>
 #include <memory>
-#include <Arduino.h>
+//#include <Arduino.h>
 
+//#include "freertos/FreeRTOS.h"
+//#include "freertos/task.h"
+//#include "freertos/semphr.h"
+//#include "freertos/queue.h"
 
-#include "freertos/FreeRTOS.h"
+//#include "esp_heap_caps.h"
-#include "freertos/task.h"
-#include "freertos/semphr.h"
-#include "freertos/queue.h"
-
-#include "esp_heap_caps.h"
 #include "platforms/platform_detect.hpp"
 
 

src/platforms/platform_detect.hpp

@@ -50,6 +50,9 @@ Modified heavily for the ESP32 HUB75 DMA library by:
   #include "esp32/esp32_i2s_parallel_dma.hpp"  
   #include "esp32/esp32-default-pins.hpp"
 
+ #else
+    #error "Unknown ESP32 platform."
+  
  #endif