Minor changes

* Fix double buffer example
* Remove the I2S user clock config for simplicity - ESP32 turns out to be massively limited anyway to 20Mhz...

4 files changed, 56 insertions, 45 deletions

diff --git a/ESP32-HUB75-MatrixPanel-I2S-DMA.cpp b/ESP32-HUB75-MatrixPanel-I2S-DMA.cpp
index 89f24ae..5a7bf34 100644
--- a/ESP32-HUB75-MatrixPanel-I2S-DMA.cpp
+++ b/ESP32-HUB75-MatrixPanel-I2S-DMA.cpp
@@ -100,11 +100,11 @@ bool MatrixPanel_I2S_DMA::allocateDMAmemory()
         
         Serial.println(F("DMA memory blocks available before any malloc's: "));
         heap_caps_print_heap_info(MALLOC_CAP_DMA);
-        
+		Serial.println(F("******************************************************************"));
         Serial.printf_P(PSTR("We're going to need %d bytes of SRAM just for the frame buffer(s).\r\n"), _frame_buffer_memory_required);  
         Serial.printf_P(PSTR("The total amount of DMA capable SRAM memory is %d bytes.\r\n"), heap_caps_get_free_size(MALLOC_CAP_DMA));
         Serial.printf_P(PSTR("Largest DMA capable SRAM memory block is %d bytes.\r\n"), heap_caps_get_largest_free_block(MALLOC_CAP_DMA));          
-		
+		Serial.println(F("******************************************************************"));		
     #endif
 
     // Can we potentially fit the framebuffer into the DMA capable memory that's available?
@@ -180,11 +180,16 @@ bool MatrixPanel_I2S_DMA::allocateDMAmemory()
 
     Serial.printf_P(PSTR("Raised lsbMsbTransitionBit to %d/%d to fit in remaining RAM\r\n"), lsbMsbTransitionBit, PIXEL_COLOR_DEPTH_BITS - 1);
 
-
+   //#define IGNORE_REFRESH_RATE 1 
    #ifndef IGNORE_REFRESH_RATE	
+   
+	#if SERIAL_DEBUG  
+	  Serial.printf_P(PSTR("Requested I2S clock / gpio output frequency is %d Mhz\r\n"), ESP32_I2S_CLOCK_SPEED/1000000);        	  
+	#endif
+		
     // calculate the lowest LSBMSB_TRANSITION_BIT value that will fit in memory that will meet or exceed the configured refresh rate
     while(1) {           
-        int psPerClock = 1000000000000UL/m_cfg.i2sspeed;
+        int psPerClock = 1000000000000UL/ESP32_I2S_CLOCK_SPEED;
         int nsPerLatch = ((PIXELS_PER_ROW + CLKS_DURING_LATCH) * psPerClock) / 1000;
 
         // add time to shift out LSBs + LSB-MSB transition bit - this ignores fractions...
@@ -198,9 +203,9 @@ bool MatrixPanel_I2S_DMA::allocateDMAmemory()
         int actualRefreshRate = 1000000000UL/(nsPerFrame);
         calculated_refresh_rate = actualRefreshRate;
 
-        #if SERIAL_DEBUG  
+        #if SERIAL_DEBUG     	
           Serial.printf_P(PSTR("lsbMsbTransitionBit of %d gives %d Hz refresh: \r\n"), lsbMsbTransitionBit, actualRefreshRate);        
-		    #endif
+		#endif
 
         if (actualRefreshRate > min_refresh_rate) // HACK Hard Coded: 100
           break;
@@ -416,7 +421,7 @@ void MatrixPanel_I2S_DMA::configureDMA(const HUB75_I2S_CFG& _cfg)
     i2s_parallel_config_t cfg={
         .gpio_bus={_cfg.gpio.r1, _cfg.gpio.g1, _cfg.gpio.b1, _cfg.gpio.r2, _cfg.gpio.g2, _cfg.gpio.b2, _cfg.gpio.lat, _cfg.gpio.oe, _cfg.gpio.a, _cfg.gpio.b, _cfg.gpio.c, _cfg.gpio.d, _cfg.gpio.e, -1, -1, -1},
         .gpio_clk=_cfg.gpio.clk,
-        .clkspeed_hz=_cfg.i2sspeed,   //ESP32_I2S_CLOCK_SPEED,  formula used is 80000000L/(cfg->clkspeed_hz + 1), must result in >=2.  Acceptable values 26.67MHz, 20MHz, 16MHz, 13.34MHz...
+        .clkspeed_hz=ESP32_I2S_CLOCK_SPEED,   //ESP32_I2S_CLOCK_SPEED,  formula used is 80000000L/(cfg->clkspeed_hz + 1), must result in >=2.  Acceptable values 26.67MHz, 20MHz, 16MHz, 13.34MHz...
         .bits=ESP32_I2S_DMA_MODE,     //ESP32_I2S_DMA_MODE,
         .bufa=0,
         .bufb=0,
diff --git a/ESP32-HUB75-MatrixPanel-I2S-DMA.h b/ESP32-HUB75-MatrixPanel-I2S-DMA.h
index e1c1067..57a79fb 100644
--- a/ESP32-HUB75-MatrixPanel-I2S-DMA.h
+++ b/ESP32-HUB75-MatrixPanel-I2S-DMA.h
@@ -230,11 +230,6 @@ struct  HUB75_I2S_CFG {
    */
   enum shift_driver {SHIFT=0, FM6124, FM6126A, ICN2038S};
 
-  /**
-   * I2S clock speed selector
-   */
-  enum clk_speed {HZ_10M=10000000, HZ_13340K=13340000, HZ_16M=16000000, HZ_20M=20000000, HZ_26670K=26670000};
-
   // Structure Variables
 
   // physical width of a single matrix panel module (in pixels, usually it is 64 ;) )
@@ -252,8 +247,7 @@ struct  HUB75_I2S_CFG {
 
   // Matrix driver chip type - default is a plain shift register
   shift_driver driver;
-  // I2S clock speed
-  clk_speed i2sspeed;
+  
   // use DMA double buffer (twice as much RAM required)
   bool double_buff;
   // How many clock cycles to blank OE before/after LAT signal change, default is 1 clock
@@ -271,13 +265,12 @@ struct  HUB75_I2S_CFG {
       LAT_PIN_DEFAULT, OE_PIN_DEFAULT, CLK_PIN_DEFAULT },
     shift_driver _drv = SHIFT,
     bool _dbuff = false,
-    clk_speed _i2sspeed = HZ_10M,
     uint16_t _latblk = 1
   ) : mx_width(_w),
       mx_height(_h),
       chain_length(_chain),
       gpio(_pinmap),
-      driver(_drv), i2sspeed(_i2sspeed),
+      driver(_drv),
       double_buff(_dbuff),
       latch_blanking(_latblk) {}
 }; // end of structure HUB75_I2S_CFG
diff --git a/esp32_i2s_parallel.c b/esp32_i2s_parallel.c
index d29b771..58cd7fe 100644
--- a/esp32_i2s_parallel.c
+++ b/esp32_i2s_parallel.c
@@ -196,12 +196,18 @@ void i2s_parallel_setup_without_malloc(i2s_dev_t *dev, const i2s_parallel_config
     else
         dev->sample_rate_conf.tx_bck_div_num=1; // datasheet says this must be 2 or greater (but 1 seems to work)
     
-    dev->clkm_conf.val=0;
-    dev->clkm_conf.clka_en=0;
-    dev->clkm_conf.clkm_div_a=63;
-    dev->clkm_conf.clkm_div_b=63;
+    dev->clkm_conf.val=0;				// Clear the clkm_conf struct
+    dev->clkm_conf.clka_en=0;			// Use the 160mhz system clock (PLL_D2_CLK) when '0'
+    dev->clkm_conf.clkm_div_a=1;		// Page 310 of Technical Reference Manual - Clock denominator
+    dev->clkm_conf.clkm_div_b=1;		// Page 310 of Technical Reference Manual - Clock numerator
     //We ignore the possibility for fractional division here, clkspeed_hz must round up for a fractional clock speed, must result in >= 2
-    dev->clkm_conf.clkm_div_num=80000000L/(cfg->clkspeed_hz + 1);
+	
+	// It's confusing, but the max output the ESP32 can pump out when using I2S *parallel* output is 20Mhz.
+	// https://easyvolts.com/2018/08/14/esp32-40msps-oscilloscope-project-is-closed-and-here-is-why/
+	// and https://github.com/espressif/esp-idf/issues/2251
+	// Igor - "Frequencies above 20MHz do not work in I2S mode."
+    dev->clkm_conf.clkm_div_num=80000000L/(cfg->clkspeed_hz + 1); // combination of this and tx_bck_div_num
+	
 
     dev->fifo_conf.val=0;
     dev->fifo_conf.rx_fifo_mod_force_en=1;
diff --git a/examples/DoubleBufferSwap/DoubleBufferSwap.ino b/examples/DoubleBufferSwap/DoubleBufferSwap.ino
index 81e116d..76e2ea2 100644
--- a/examples/DoubleBufferSwap/DoubleBufferSwap.ino
+++ b/examples/DoubleBufferSwap/DoubleBufferSwap.ino
@@ -10,8 +10,8 @@
  * for different resolutions / panel chain lengths within the sketch 'setup()'.
  * 
  */
-MatrixPanel_I2S_DMA     display(true);      // Note the TRUE -> Turns of secondary buffer - "double buffering"!
-                                                    // Double buffering is not enabled by default with the library.
+
+MatrixPanel_I2S_DMA *display = nullptr;
 
 const byte row0 = 2+0*10;
 const byte row1 = 2+1*10;
@@ -26,30 +26,37 @@ void setup()
 
   Serial.println("...Starting Display");
   
-  display.begin();  // setup display with pins as per defined in the library
-  display.setTextColor(display.color565(128, 128, 128));  
+  HUB75_I2S_CFG mxconfig;
+  mxconfig.double_buff = true; // Turn of double buffer
+
+  // OK, now we can create our matrix object
+  display = new MatrixPanel_I2S_DMA(mxconfig);  
+  
+  
+  display->begin();  // setup display with pins as per defined in the library
+  display->setTextColor(display->color565(255, 255, 255));  
 
   
   // Buffer 0 test
-  display.fillScreen(display.color565(128, 0, 0));  
-  display.setCursor(3, row0);
-  display.print(F("Buffer 0"));
-  display.setCursor(3, row1);
-  display.print(F(" Buffer 0"));
+  display->fillScreen(display->color565(128, 0, 0));  
+  display->setCursor(3, row0);
+  display->print(F("Buffer 0"));
+  display->setCursor(3, row1);
+  display->print(F(" Buffer 0"));
   Serial.println("Wrote to to Buffer 0");
-  display.showDMABuffer(); 
+  display->showDMABuffer(); 
   delay(1500);
   
   // Buffer 1 test
-  display.flipDMABuffer();
-  display.fillScreen(display.color565(0, 128, 0)); // shouldn't see this
-  display.setCursor(3, row0);
-  display.print(F("Buffer 1"));
-  display.setCursor(3, row2);
-  display.print(F(" Buffer 1"));
+  display->flipDMABuffer();
+  display->fillScreen(display->color565(0, 128, 0)); // shouldn't see this
+  display->setCursor(3, row0);
+  display->print(F("Buffer 1"));
+  display->setCursor(3, row2);
+  display->print(F(" Buffer 1"));
  
   Serial.println("Wrote to to Buffer 1");
-  display.showDMABuffer();  
+  display->showDMABuffer();  
   delay(1500);
 
 }
@@ -57,31 +64,31 @@ void setup()
 void loop() {
   
   // Flip the back buffer
-  display.flipDMABuffer();
+  display->flipDMABuffer();
 
   // Write: Set bottow row to black
   for (int y=20;y<MATRIX_HEIGHT; y++)
   for (int x=0;x<MATRIX_WIDTH; x++)
   {
-    display.drawPixelRGB888( x, y, 0, 0, 0);
+    display->drawPixelRGB888( x, y, 0, 0, 0);
   }
 
   // Write:  Set bottom row to blue (this is what should show)
   for (int y=20;y<MATRIX_HEIGHT; y++)
   for (int x=0;x<MATRIX_WIDTH; x++)
   {
-    display.drawPixelRGB888( x, y, 0, 0, 64);
+    display->drawPixelRGB888( x, y, 0, 0, 64);
   }
 
   // Now show this back buffer
-  display.showDMABuffer();  
+  display->showDMABuffer();  
   delay(1000);
 
   // Flip back buffer
-  display.flipDMABuffer();   
+  display->flipDMABuffer();   
 
   // Show this buffer
-  display.showDMABuffer();   
+  display->showDMABuffer();   
   delay(1000); 
 
-}
+}
\ No newline at end of file