Merge branch 'master' of https://twinetfs.visualstudio.com/Tango/_git/Tango

1 files changed, 13 insertions, 8 deletions

diff --git a/Software/Embedded_SW/Embedded/Drivers/I2C_Communication/I2C_Comm.c b/Software/Embedded_SW/Embedded/Drivers/I2C_Communication/I2C_Comm.c
index 99c865d87..9bcdec476 100644
--- a/Software/Embedded_SW/Embedded/Drivers/I2C_Communication/I2C_Comm.c
+++ b/Software/Embedded_SW/Embedded/Drivers/I2C_Communication/I2C_Comm.c
@@ -54,7 +54,7 @@ uint32_t I2C_WriteBuff(uint32_t I2C_BASE, unsigned char addr, unsigned char* dat
     if (len == 1)
     {
         I2CMasterControl(I2C_BASE, I2C_MASTER_CMD_SINGLE_SEND);
-        SysCtlDelay(I2C_BUSY_DELAY);
+        SysCtlDelay(I2C_BUSY_DELAY);//The CPU waits for the Command processing to begin before it goes to check if the command is processed
         while(I2CMasterBusy(I2C_BASE));
         status |= I2CMasterErr(I2C_BASE);
     }
@@ -62,7 +62,7 @@ uint32_t I2C_WriteBuff(uint32_t I2C_BASE, unsigned char addr, unsigned char* dat
     {
         // Start sending consecutive data
         I2CMasterControl(I2C_BASE, I2C_MASTER_CMD_BURST_SEND_START);
-        SysCtlDelay(I2C_BUSY_DELAY);
+        SysCtlDelay(I2C_BUSY_DELAY);//The CPU waits for the Command processing to begin before it goes to check if the command is processed
         while(I2CMasterBusy(I2C_BASE));
         status |= I2CMasterErr(I2C_BASE);
 
@@ -73,7 +73,7 @@ uint32_t I2C_WriteBuff(uint32_t I2C_BASE, unsigned char addr, unsigned char* dat
         while(len > 1){
             I2CMasterDataPut(I2C_BASE, *data);
             I2CMasterControl(I2C_BASE, I2C_MASTER_CMD_BURST_SEND_CONT);
-            SysCtlDelay(I2C_BUSY_DELAY);
+            SysCtlDelay(I2C_BUSY_DELAY);//The CPU waits for the Command processing to begin before it goes to check if the command is processed
             while(I2CMasterBusy(I2C_BASE));
             status |= I2CMasterErr(I2C_BASE);
 
@@ -84,7 +84,7 @@ uint32_t I2C_WriteBuff(uint32_t I2C_BASE, unsigned char addr, unsigned char* dat
         // Send last piece of data
         I2CMasterDataPut(I2C_BASE, *data);
         I2CMasterControl(I2C_BASE, I2C_MASTER_CMD_BURST_SEND_FINISH);
-        SysCtlDelay(I2C_BUSY_DELAY);
+        SysCtlDelay(I2C_BUSY_DELAY);//The CPU waits for the Command processing to begin before it goes to check if the command is processed
         while(I2CMasterBusy(I2C_BASE));
         status |= I2CMasterErr(I2C_BASE);
     }
@@ -113,7 +113,12 @@ uint32_t I2C_ReadBuff(uint32_t I2C_BASE, unsigned char addr, unsigned char* data
     if (len == 1)
     {
         I2CMasterControl(I2C_BASE, I2C_MASTER_CMD_SINGLE_RECEIVE);
-        SysCtlDelay(I2C_BUSY_DELAY);
+        //On the TM4C129 we discovered a design behavior that due to higher system clock frequency and lower I2C baud rate,
+        //the CPU when it starts a I2C Transaction or writes a new I2C Command, for the I2C to respond to it takes time.
+        //So in effect the I2CMasterBusy statement gets skipped which causes The I2C controller to lose data.
+        //see: https://e2e.ti.com/support/microcontrollers/other/f/908/t/368493?Why-is-a-delay-needed-before-writing-the-first-byte-from-I2C-Master-
+        //therefore we need delay before waiting until bus is not busy  - it doesn't work as expected without it or with while(!(I2CMasterBusy(I2C0_BASE)
+        SysCtlDelay(I2C_BUSY_DELAY);//The CPU waits for the Command processing to begin before it goes to check if the command is processed
         while(I2CMasterBusy(I2C_BASE));
         *data = I2CMasterDataGet(I2C_BASE);
         status |= I2CMasterErr(I2C_BASE);
@@ -123,7 +128,7 @@ uint32_t I2C_ReadBuff(uint32_t I2C_BASE, unsigned char addr, unsigned char* data
 
         // Start receiving consecutive data
         I2CMasterControl(I2C_BASE, I2C_MASTER_CMD_BURST_RECEIVE_START);
-        SysCtlDelay(I2C_BUSY_DELAY);
+        SysCtlDelay(I2C_BUSY_DELAY);//The CPU waits for the Command processing to begin before it goes to check if the command is processed
         while(I2CMasterBusy(I2C_BASE));
         *data = I2CMasterDataGet(I2C_BASE);
         status |= I2CMasterErr(I2C_BASE);
@@ -135,7 +140,7 @@ uint32_t I2C_ReadBuff(uint32_t I2C_BASE, unsigned char addr, unsigned char* data
         // Continue receiving consecutive data
         while(len > 1){
             I2CMasterControl(I2C_BASE, I2C_MASTER_CMD_BURST_RECEIVE_CONT);
-           SysCtlDelay(I2C_BUSY_DELAY);
+           SysCtlDelay(I2C_BUSY_DELAY);//The CPU waits for the Command processing to begin before it goes to check if the command is processed
            while(I2CMasterBusy(I2C_BASE));
             *data = I2CMasterDataGet(I2C_BASE);
             status |= I2CMasterErr(I2C_BASE);
@@ -146,7 +151,7 @@ uint32_t I2C_ReadBuff(uint32_t I2C_BASE, unsigned char addr, unsigned char* data
 
         // Receive last piece of data
         I2CMasterControl(I2C_BASE, I2C_MASTER_CMD_BURST_RECEIVE_FINISH);
-        SysCtlDelay(I2C_BUSY_DELAY);
+        SysCtlDelay(I2C_BUSY_DELAY);//The CPU waits for the Command processing to begin before it goes to check if the command is processed
         while(I2CMasterBusy(I2C_BASE));
         *data = I2CMasterDataGet(I2C_BASE);
         status |= I2CMasterErr(I2C_BASE);