From 47323abef3896f85d87aadf3d6ef849176cd44d8 Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Sat, 30 Jun 2018 10:54:16 +0200
Subject: [PATCH] Whoa! Interrupt-driven I2C is working!

---
 Inc/app.h          |  4 ++
 Src/bmp085.c       | 94 +++++++++++++---------------------------------
 Src/stm32f1xx_it.c | 46 +++++++++++++++++++++++
 3 files changed, 76 insertions(+), 68 deletions(-)

diff --git a/Inc/app.h b/Inc/app.h
index 9eb2b0d..acae0ae 100644
--- a/Inc/app.h
+++ b/Inc/app.h
@@ -19,5 +19,9 @@ void tx_packet_send(void);
 extern s16 adjusted_temp;
 extern s16 adjusted_press;
 
+extern volatile byte *bmp_i2c_ptr;
+extern volatile byte bmp_i2c_len;
+extern volatile byte bmp_i2c_addr;
+
 void bmp_init(void);
 void bmp_step(void);
diff --git a/Src/bmp085.c b/Src/bmp085.c
index 76c6481..d150b90 100644
--- a/Src/bmp085.c
+++ b/Src/bmp085.c
@@ -4,82 +4,37 @@
 #include "util.h"
 #include "app.h"
 
+static byte bmp_i2c_buf[4];
+volatile byte *bmp_i2c_ptr;
+volatile byte bmp_i2c_len;
+volatile byte bmp_i2c_addr;
+
 static uint bmp_read(uint reg, uint bytes)
 {
+  bmp_i2c_buf[0] = reg;
+  bmp_i2c_ptr = bmp_i2c_buf;
+  bmp_i2c_len = 1;
+  bmp_i2c_addr = 0xee;
+
   LL_I2C_GenerateStartCondition(I2C1);
-  while (!LL_I2C_IsActiveFlag_SB(I2C1))
-    ;
-  LL_I2C_TransmitData8(I2C1, 0xee);
-  while (!LL_I2C_IsActiveFlag_ADDR(I2C1))
-    ;
-  LL_I2C_ClearFlag_ADDR(I2C1);
-  while (!LL_I2C_IsActiveFlag_TXE(I2C1))
-    ;
-  LL_I2C_TransmitData8(I2C1, reg);
-  while (!LL_I2C_IsActiveFlag_TXE(I2C1))
+  LL_I2C_EnableIT_TX(I2C1);
+
+  while (bmp_i2c_len)
     ;
-  LL_I2C_GenerateStopCondition(I2C1);
+
+  bmp_i2c_ptr = bmp_i2c_buf;
+  bmp_i2c_len = bytes;
+  bmp_i2c_addr = 0xef;
 
   LL_I2C_GenerateStartCondition(I2C1);
-  while (!LL_I2C_IsActiveFlag_SB(I2C1))
-    ;
-  LL_I2C_DisableBitPOS(I2C1);
-  LL_I2C_TransmitData8(I2C1, 0xef);
-  while (!LL_I2C_IsActiveFlag_ADDR(I2C1))
+  LL_I2C_EnableIT_RX(I2C1);
+
+  while (bmp_i2c_len)
     ;
 
-  // This is quite tricky (see manual)
   uint d = 0;
-  if (bytes == 1)
-    {
-      LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_NACK);
-      LL_I2C_ClearFlag_ADDR(I2C1);
-      LL_I2C_GenerateStopCondition(I2C1);
-      while (!LL_I2C_IsActiveFlag_RXNE(I2C1))
-	;
-      d = (d << 8) | LL_I2C_ReceiveData8(I2C1);
-    }
-  else if (bytes == 2)
-    {
-      LL_I2C_EnableBitPOS(I2C1);
-      LL_I2C_ClearFlag_ADDR(I2C1);
-      LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_NACK);
-      while (!LL_I2C_IsActiveFlag_BTF(I2C1))
-	;
-      LL_I2C_GenerateStopCondition(I2C1);
-      for (uint i=0; i<2; i++)
-	d = (d << 8) | LL_I2C_ReceiveData8(I2C1);
-    }
-  else
-    {
-      LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_ACK);
-      LL_I2C_ClearFlag_ADDR(I2C2);
-
-      uint d = 0;
-      for (uint i=0; i<bytes; i++)
-	{
-	  if (i+3 < bytes || i+1 == bytes)
-	    {
-#if 0
-	      while (!LL_I2C_IsActiveFlag_RXNE(I2C1))
-		;
-#endif
-	    }
-	  else if (i+3 == bytes)
-	    {
-	      while (!LL_I2C_IsActiveFlag_BTF(I2C1))
-		;
-	      LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_NACK);
-	    }
-	  else if (i+2 == bytes)
-	    {
-	      while (!LL_I2C_IsActiveFlag_BTF(I2C1))
-		;
-	      LL_I2C_GenerateStopCondition(I2C1);
-	    }
-	  d = (d << 8) | LL_I2C_ReceiveData8(I2C1);
-	}
-    }
+  for (uint i=0; i<bytes; i++)
+    d = (d << 8) | bmp_i2c_buf[i];
 
   return d;
 }
@@ -158,7 +113,10 @@ static u16 bmp_constants[11];
 void bmp_init(void)
 {
   for (uint i=0; i<11; i++)
-    bmp_constants[i] = bmp_read(0xaa + 2*i, 2);
+    {
+      bmp_constants[i] = bmp_read(0xaa + 2*i, 2);
+      debug_printf("BMP: const[%d] = %u\n", i, bmp_constants[i]);
+    }
 }
 
 enum bmp_state {
diff --git a/Src/stm32f1xx_it.c b/Src/stm32f1xx_it.c
index 68d7309..c571e46 100644
--- a/Src/stm32f1xx_it.c
+++ b/Src/stm32f1xx_it.c
@@ -246,6 +246,52 @@ void TIM4_IRQHandler(void)
 void I2C1_EV_IRQHandler(void)
 {
   /* USER CODE BEGIN I2C1_EV_IRQn 0 */
+  u32 sr1 = I2C1->SR1;
+  if (sr1 & I2C_SR1_SB)
+    LL_I2C_TransmitData8(I2C1, bmp_i2c_addr);
+  else if (bmp_i2c_addr & 1)
+    {
+      // Receive
+      if (sr1 & I2C_SR1_ADDR)
+	{
+	  LL_I2C_DisableBitPOS(I2C1);
+	  if (bmp_i2c_len == 1)
+	    LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_NACK);
+	  LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_ACK);
+	  LL_I2C_ClearFlag_ADDR(I2C1);
+	}
+      else if (sr1 & I2C_SR1_RXNE)
+	{
+	  if (bmp_i2c_len > 0)
+	    {
+	      if (bmp_i2c_len == 1)
+		{
+		  LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_NACK);
+		  LL_I2C_GenerateStopCondition(I2C1);
+		}
+	      *bmp_i2c_ptr++ = LL_I2C_ReceiveData8(I2C1);
+	      bmp_i2c_len--;
+	    }
+	  else
+	    LL_I2C_DisableIT_RX(I2C1);
+	}
+    }
+  else
+    {
+      // Transmit
+      if (sr1 & I2C_SR1_ADDR)
+	LL_I2C_ClearFlag_ADDR(I2C1);
+      else if (sr1 & I2C_SR1_TXE)
+	{
+	  if (bmp_i2c_len)
+	    {
+	      LL_I2C_TransmitData8(I2C1, *bmp_i2c_ptr++);
+	      bmp_i2c_len--;
+	    }
+	  else
+	    LL_I2C_DisableIT_TX(I2C1);
+	}
+    }
 
   /* USER CODE END I2C1_EV_IRQn 0 */
   
-- 
2.39.2