From 664e1c88ac55cd0cde605deacf98878e86abd736 Mon Sep 17 00:00:00 2001
From: Roger Clark <roger@rogerclark.net>
Date: Mon, 30 Mar 2015 06:47:26 +1100
Subject: [PATCH] Second attempt at SPI::DMATransfer. Now uses separate tx and
 rx buffers, and I also added code to wait for tx to complete and SPI to not
 be busy before exiting the function. Note. Operation of rx buffer has not
 been tested

---
 .../Adafruit_ILI9341/Adafruit_ILI9341.cpp     | 10 +++---
 STM32F1/libraries/SPI/src/SPI.cpp             | 33 ++++++++++++-------
 STM32F1/libraries/SPI/src/SPI.h               |  5 ++-
 3 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/STM32F1/libraries/Adafruit_ILI9341/Adafruit_ILI9341.cpp b/STM32F1/libraries/Adafruit_ILI9341/Adafruit_ILI9341.cpp
index e8eba84..4233716 100644
--- a/STM32F1/libraries/Adafruit_ILI9341/Adafruit_ILI9341.cpp
+++ b/STM32F1/libraries/Adafruit_ILI9341/Adafruit_ILI9341.cpp
@@ -457,19 +457,21 @@ void Adafruit_ILI9341::fillRect(int16_t x, int16_t y, int16_t w, int16_t h,  uin
 	if (true)
 	{
 		// Use DMA
-		byte lineBuffer[h*2];// Buffer to be sent via DMA
+		byte txBuf[h*2];// Buffer to be sent via DMA
+		byte rxBuf[h*2];// Buffer to be sent via DMA
 	  
 	    // need to build a buffer of the required height  (h) 
 		// Note I suspect there is a faster way to do this
 		for(int i=0;i<h*2;i++)
 		{
-			lineBuffer[i++] = hi&0xff;
-			lineBuffer[i]   = lo&0xff;
+			txBuf[i++] = hi&0xff;
+			txBuf[i]   = lo&0xff;
 		}
 		// Tansfer each line by DMA
 		for(int i=0;i<w;i++)
 		{
-			SPI.DMATransfer(lineBuffer,h*2);
+			//memcpy(rxBuf,txBuf,h*2);
+			SPI.DMATransfer(txBuf,rxBuf,h*2);
 		}
 	}
 	else
diff --git a/STM32F1/libraries/SPI/src/SPI.cpp b/STM32F1/libraries/SPI/src/SPI.cpp
index b9caaad..e17d265 100644
--- a/STM32F1/libraries/SPI/src/SPI.cpp
+++ b/STM32F1/libraries/SPI/src/SPI.cpp
@@ -330,24 +330,33 @@ uint8 SPIClass::transfer(uint8 byte) {
     return b;
 }
 
-uint8 SPIClass::DMATransfer(uint8 *data, uint32 length) {
+uint8 SPIClass::DMATransfer(uint8 *transmitBuf, uint8 *receiveBuf, uint32 length) {
 	uint8 b;
-	
 
-	
 	dma1_ch3_Active=true;
-	
-    spi_tx_dma_enable(SPI1);
-    dma_init(DMA1);
-	
 
-    dma_attach_interrupt(DMA1, DMA_CH3, &SPIClass::DMA1_CH3_Event);
+    dma_init(DMA1);
+
+    dma_attach_interrupt(DMA1, DMA_CH2, &SPIClass::DMA1_CH3_Event);
+
+	// RX
+	spi_rx_dma_enable(SPI1);
+	dma_setup_transfer(DMA1, DMA_CH2, &SPI1->regs->DR, DMA_SIZE_8BITS,
+                     receiveBuf, DMA_SIZE_8BITS, (DMA_MINC_MODE | DMA_TRNS_CMPLT | DMA_TRNS_ERR));// receive buffer DMA
+	dma_set_num_transfers(DMA1, DMA_CH2, length);
+		
+	// TX
+    spi_tx_dma_enable(SPI1);				 
     dma_setup_transfer(DMA1, DMA_CH3, &SPI1->regs->DR, DMA_SIZE_8BITS,
-                       data, DMA_SIZE_8BITS, (DMA_MINC_MODE |  DMA_FROM_MEM | DMA_TRNS_CMPLT));
+                       transmitBuf, DMA_SIZE_8BITS, (DMA_MINC_MODE |  DMA_FROM_MEM | DMA_TRNS_CMPLT));// Transmit buffer DMA
+    dma_set_num_transfers(DMA1, DMA_CH3, length); 
+	  
+	dma_enable(DMA1, DMA_CH2);// enable receive
+	dma_enable(DMA1, DMA_CH3);// enable transmit
 	
-	  dma_set_num_transfers(DMA1, DMA_CH3, length); // 2 bytes per pixel
-	  dma_enable(DMA1, DMA_CH3);
-	  while (dma1_ch3_Active);
+	while (dma1_ch3_Active);
+	while (spi_is_tx_empty(this->spi_d) == 0); // "5. Wait until TXE=1 ..."
+	while (spi_is_busy(this->spi_d) != 0); // "... and then wait until BSY=0 before disabling the SPI."   
 	
     return b;
 }
diff --git a/STM32F1/libraries/SPI/src/SPI.h b/STM32F1/libraries/SPI/src/SPI.h
index 3a32e39..7a8ea0d 100644
--- a/STM32F1/libraries/SPI/src/SPI.h
+++ b/STM32F1/libraries/SPI/src/SPI.h
@@ -228,7 +228,7 @@ public:
      */
     uint8 transfer(uint8 data);
 
-    uint8 DMATransfer(uint8 *data, uint32 length);
+	uint8 DMATransfer(uint8 *transmitBuf, uint8 *receiveBuf, uint32 length);
 
     /*
      * Pin accessors
@@ -303,6 +303,9 @@ private:
 	static inline void DMA1_CH3_Event() {
 		dma1_ch3_Active = 0;
 		dma_disable(DMA1, DMA_CH3);
+		dma_disable(DMA1, DMA_CH2);
+		
+		// To Do. Need to wait for 
 	}
 	spi_dev *spi_d;
 	uint8_t _SSPin;