Revision 2:ef928f61a770, committed 2014-12-21

Comitter:

wim

Date:

Sun Dec 21 15:09:10 2014 +0000

Parent:

1:bae4cff278f6

Child:

3:e5af2e131b95

Commit message:

Added comments and documentation

Changed in this revision

--- a/SWO.cpp	Sat Dec 20 22:30:12 2014 +0000
+++ b/SWO.cpp	Sun Dec 21 15:09:10 2014 +0000
@@ -1,7 +1,7 @@
 /* mbed SWO Library
- *  Copyright (c) 2014, v01: WH. Ported from Segger example
+ *  Copyright (c) 2014, v01: WH. Ported from Segger example (www.segger.com)
  *
- * Simple implementation for tracing via Single Wire Output(SWO) for Cortex-M processors.
+ * Simple implementation for tracing via Serial Wire Output(SWO) for Cortex-M processors.
  * It can be used with Host PC software such as ST-LINK Utility or Segger J-Link SWO viewer.
  * This sample implementation ensures that output via SWO is enabled in order to guarantee
  * that the application does not hang.
@@ -24,22 +24,100 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
-
+#include "mbed.h"
 #include "SWO.h"
 
 /**
- *
  * Defines for Cortex-M debug unit
  */
 #define ITM_STIM_U32(n) (*(volatile unsigned int*)(0xE0000000+4*n))  // Stimulus Port n Register word access
-#define ITM_STIM_U8(n)  (*(volatile         char*)(0xE0000000+n))    // Stimulus Port n Register byte access
+#define ITM_STIM_U8(n)  (*(volatile         char*)(0xE0000000+4*n))  // Stimulus Port n Register byte access
 //#define ITM_STIM_U32_0  (*(volatile unsigned int*)0xE0000000)        // Stimulus Port 0 Register word access
 //#define ITM_STIM_U8_0   (*(volatile         char*)0xE0000000)        // Stimulus Port 0 Register byte access
 #define ITM_ENA         (*(volatile unsigned int*)0xE0000E00)        // Trace Enable Ports Register
 #define ITM_TCR         (*(volatile unsigned int*)0xE0000E80)        // Trace control register
 
+#define ITM_STIM_FIFOREADY                        0x00000001         // FIFO empty
+
+//Stuff below is for documentation and needs further testing
+// It seems that the Segger SWO Viewer and the ST-Link Utility do most/all of these
+// initialisations on the target before starting the session. This is probably not the case 
+// when using GDB/OpenOCD.
+//
+//
+#if(0)
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/gpio.h>
+
+#include <libopencm3/stm32/dbgmcu.h>
+#include <libopencm3/cm3/scs.h>
+#include <libopencm3/cm3/tpiu.h>
+#include <libopencm3/cm3/itm.h> 
+
 /**
+ * SWO_Setup() Example
  *
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de> 
+ * https://github.com/1divf/libopenstm32/blob/master/examples/stm32/stm32-h103/traceswo/traceswo.c
+ *
+ */
+void SWO_Setup(void) { 
+    /* Enable trace subsystem (we'll use ITM and TPIU) */
+    SCS_DEMCR |= SCS_DEMCR_TRCENA;
+
+    /* Use Manchester code for asynchronous transmission */
+    TPIU_SPPR = TPIU_SPPR_ASYNC_MANCHESTER;
+    TPIU_ACPR = 7;
+
+    /* Data width is 1 byte */
+    TPIU_CSPSR = TPIU_CSPSR_BYTE;
+
+    /* Formatter and flush control */
+    TPIU_FFCR &= ~TPIU_FFCR_ENFCONT;
+
+    /* Enable TRACESWO pin for async mode */
+    DBGMCU_CR = DBGMCU_CR_TRACE_IOEN | DBGMCU_CR_TRACE_MODE_ASYNC;
+
+    /* Unlock access to ITM registers */
+    /* FIXME: Magic numbers... Is this Cortex-M3 generic? */
+    *((volatile uint32_t*)0xE0000FB0) = 0xC5ACCE55;
+
+    /* Enable ITM with ID = 1 */
+    ITM_TCR = (1 << 16) | ITM_TCR_ITMENA;
+    /* Enable stimulus port 1 */
+    ITM_TER[0] = 1; 
+}
+
+/**
+ * SWO_Setup() Example
+ *
+ * http://forum.segger.com/index.php?page=Thread&threadID=608
+ *
+ */
+void SWO_Setup_1(void) { 
+  U32 SWOPrescaler;
+  U32 SWOSpeed;
+
+//<Init PLL, set CPU clock to 72 MHz>  // Optional, so I do not pos it here
+
+  SWOSpeed = 6000000;
+   *((volatile unsigned *)0xE000EDFC) = 0x01000000;   // "Debug Exception and Monitor Control Register (DEMCR)"
+   *((volatile unsigned *)0xE0042004) = 0x00000027;
+   *((volatile unsigned *)0xE00400F0) = 0x00000002;   // "Selected PIN Protocol Register": Select which protocol to use for trace output (2: SWO)
+  SWOPrescaler = (72000000 / SWOSpeed) - 1;  // SWOSpeed in Hz
+   *((volatile unsigned *)0xE0040010) = SWOPrescaler; // "Async Clock Prescaler Register". Scale the baud rate of the asynchronous output
+   *((volatile unsigned *)0xE0000FB0) = 0xC5ACCE55;   // ITM Lock Access Register, C5ACCE55 enables more write access to Control Register 0xE00 :: 0xFFC
+   *((volatile unsigned *)0xE0000E80) = 0x0001000D;   // ITM Trace Control Register
+   *((volatile unsigned *)0xE0000E40) = 0x0000000F;   // ITM Trace Privilege Register
+   *((volatile unsigned *)0xE0000E00) = 0x00000001;   // ITM Trace Enable Register. Enabled tracing on stimulus ports. One bit per stimulus port.
+   *((volatile unsigned *)0xE0001000) = 0x400003FE;   // DWT_CTRL
+   *((volatile unsigned *)0xE0040304) = 0x00000100;   // Formatter and Flush Control Register
+}
+#endif
+
+/**
  * SWO_PrintChar()
  *
  * @brief 
@@ -52,6 +130,13 @@
  */
 void SWO_PrintChar(char c) {
 
+#if(1)
+//Use CMSIS_core_DebugFunctions. See core_cm3.h
+  ITM_SendChar (c);
+
+#else
+//Use Segger example. Basically same as CMSIS
+
   // Check if ITM_TCR.ITMENA is set
   if ((ITM_TCR & 1) == 0) {
     return;
@@ -63,15 +148,17 @@
   }
 
   // Wait until STIMx FIFO is ready, then send data
-  while ((ITM_STIM_U8(0) & 1) == 0);
+//  while ((ITM_STIM_U8(0) & 1) == 0);
+  while (!(ITM_STIM_U8(0) & ITM_STIM_FIFOREADY));    
   ITM_STIM_U8(0) = c;
-
+  
 //  while ((ITM_STIM_U32(0) & 1) == 0);
 //  ITM_STIM_U32(0) = c;
+
+#endif
 }
 
 /**
- *
  * SWO_PrintString()
  *
  * @brief Print a string via SWO.

--- a/SWO.h	Sat Dec 20 22:30:12 2014 +0000
+++ b/SWO.h	Sun Dec 21 15:09:10 2014 +0000
@@ -1,7 +1,7 @@
 /* mbed SWO Library
  *  Copyright (c) 2014, v01: WH. Ported from Segger example
  *
- * Simple implementation for tracing via Single Wire Output(SWO) for Cortex-M processors.
+ * Simple implementation for tracing via Serial Wire Output(SWO) for Cortex-M processors.
  * It can be used with Host PC software such as ST-LINK Utility or Segger J-Link SWO viewer.
  * This sample implementation ensures that output via SWO is enabled in order to guarantee
  * that the application does not hang.