Configure Swo Output After Device Reset; Target Example Code For Terminal Output - Segger J-Link User Manual

Syntax
-swofreq <SWOFreq>
Example
-swofreq 6000
3.7.3

Configure SWO output after device reset

In some situations it might happen that the target application is reset and it is
desired to log the SWO output of the target after reset during the booting process.
For such situations, the target application itself needs to initialize the CPU for SWO
output, since the SWO Viewer is not restarted but continuously running.
Example code for enabling SWO out of the target application
#define ITM_ENA
#define ITM_TPR
#define ITM_TCR
#define ITM_LSR
#define DHCSR
#define DEMCR
#define TPIU_ACPR
#define TPIU_SPPR
#define DWT_CTRL
#define FFCR
U32 _ITMPort = 0; // The stimulus port from which SWO data is received and displayed.
U32 TargetDiv = 1;// Has to be calculated according to
static void _EnableSWO() {
U32 StimulusRegs;
//
// Enable access to SWO registers
//
DEMCR |= (1 << 24);
ITM_LSR = 0xC5ACCE55;
//
// Initially disable ITM and stimulus port
// To make sure that nothing is transferred via SWO
// when changing the SWO prescaler etc.
//
Stimulusregs = ITM_ENA;
StimulusRegs &= ~(1 << _ITMPort);
ITM_ENABLE = StimulusRegs;
ITM_TCR = 0;
//
// Initialize SWO (prescaler, etc.)
//
TPIU_SPPR = 0x00000002;
TPIU_ACPR = TargetDiv - 1;
ITM_TPR = 0x00000000;
DWT_CTRL = 0x400003FE;
FFCR = 0x00000100;
//
// Enable ITM and stimulus port
//
ITM_TCR
ITM_ENA
}
3.7.4

Target example code for terminal output

/*********************************************************************
*
* Solutions for real time microcontroller applications
**********************************************************************
*
* (c) 2012-2013
*
* www.segger.com
J-Link / J-Trace (UM08001)
(*(volatile unsigned int*)0xE0000E00) // ITM Enable
(*(volatile unsigned int*)0xE0000E40) // Trace Privilege Register
(*(volatile unsigned int*)0xE0000E80) // ITM Trace Control Reg.
(*(volatile unsigned int*)0xE0000FB0) // ITM Lock Status Register
(*(volatile unsigned int*)0xE000EDF0) // Debug register
(*(volatile unsigned int*)0xE000EDFC) // Debug register
(*(volatile unsigned int*)0xE0040010) // Async Clock
(*(volatile unsigned int*)0xE00400F0) // Selected Pin Protocol
(*(volatile unsigned int*)0xE0001000) // DWT Control Register
(*(volatile unsigned int*)0xE0040304) // Formatter and flush
// the CPU speed and the output baud rate
= 0x1000D;
= StimulusRegs | (1 << _ITMPort));
SEGGER MICROCONTROLLER GmbH & Co KG
SEGGER Microcontroller GmbH & Co KG
Support: support@segger.com
// presacler register
// Register
// Control Register
// Disable ITM stimulus port
// Disable ITM
// Select NRZ mode
// Example: 72/48 = 1,5 MHz
// Enable ITM
// Enable ITM stimulus port
© 2004-2013 SEGGER Microcontroller GmbH & Co. KG
105
\
\
\
\
*
*
*
*
*
*