From 76177aa280494bb36d7a0bcbda1078d4db717020 Mon Sep 17 00:00:00 2001 From: Ali Labbene Date: Mon, 9 Dec 2019 11:25:19 +0100 Subject: Official ARM version: v4.5 --- .../Core/html/group___i_t_m___debug__gr.html | 280 +++++++++++++++++++++ 1 file changed, 280 insertions(+) create mode 100644 Documentation/Core/html/group___i_t_m___debug__gr.html (limited to 'Documentation/Core/html/group___i_t_m___debug__gr.html') diff --git a/Documentation/Core/html/group___i_t_m___debug__gr.html b/Documentation/Core/html/group___i_t_m___debug__gr.html new file mode 100644 index 0000000..5c40fd2 --- /dev/null +++ b/Documentation/Core/html/group___i_t_m___debug__gr.html @@ -0,0 +1,280 @@ + + + + + +Debug Access +CMSIS-CORE: Debug Access + + + + + + + + + + + + + + + +
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CMSIS-CORE +  Version 4.30 +
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CMSIS-CORE support for Cortex-M processor-based devices
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+Functions | +Variables
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Debug Access
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Debug Access to the Instrumented Trace Macrocell (ITM) +More...

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+Functions

uint32_t ITM_SendChar (uint32_t ch)
 Transmits a character via channel 0.
 
int32_t ITM_ReceiveChar (void)
 ITM Receive Character.
 
int32_t ITM_CheckChar (void)
 ITM Check Character.
 
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volatile int32_t ITM_RxBuffer
 external variable to receive characters
 
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Description

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CMSIS provides additional debug functions to enlarge the Debug Access. Data can be transmitted via a certain global buffer variable towards the target system.

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The Cortex-M3 / Cortex-M4 / Cortex-M7 incorporates the Instrumented Trace Macrocell (ITM) that provides together with the Serial Viewer Output (SVO) trace capabilities for the microcontroller system. The ITM has 32 communication channels; two ITM communication channels are used by CMSIS to output the following information:

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  • ITM Channel 0: implements the ITM_SendChar function which can be used for printf-style output via the debug interface.
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  • ITM Channel 31: is reserved for the RTOS kernel and can be used for kernel awareness debugging.
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Remarks
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  • ITM channels have 4 groups with 8 channels each, whereby each group can be configured for access rights in the Unprivileged level.
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  • The ITM channel 0 can be enabled for the user task.
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  • ITM channel 31 can be accessed only in Privileged mode from the RTOS kernel itself. The ITM channel 31 has been selected for the RTOS kernel because some kernels may use the Privileged level for program execution.
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+ITM Debugger Support

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A debugger may support a Debug (printf) Viewer window to display data.

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Direction: Microcontroller –> Debugger:

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  • Characters received via ITM communication channel 0 are written in a printf-style to the Debug (printf) Viewer window.
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Direction: Debugger –> Microcontroller:

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  • Check if ITM_RxBuffer variable is available (only performed once).
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  • Read the character from the Debug (printf) Viewer window.
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  • If ITM_RxBuffer is empty, write character to ITM_RxBuffer.
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Note
The current solution does not use a buffer mechanism for transmitting the characters.
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+Example:

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Example for the usage of the ITM Channel 31 for RTOS Kernels:

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// check if debugger connected and ITM channel enabled for tracing
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if ((CoreDebug->DEMCR & CoreDebug_DEMCR_TRCENA) &&
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(ITM->TCR & ITM_TCR_ITMENA) &&
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(ITM->TER & (1UL >> 31))) {
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// transmit trace data
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while (ITM->PORT31_U32 == 0);
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ITM->PORT[31].u8 = task_id; // id of next task
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while (ITM->PORT[31].u32 == 0);
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ITM->PORT[31].u32 = task_status; // status information
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}
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Function Documentation

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int32_t ITM_CheckChar (void )
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This function reads the external variable ITM_RxBuffer and checks whether a character is available or not.

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Returns
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  • =0 - No character available
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  • =1 - Character available
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int32_t ITM_ReceiveChar (void )
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This function inputs a character via the external variable ITM_RxBuffer. It returns when no debugger is connected that has booked the output. It is blocking when a debugger is connected, but the previously sent character has not been transmitted.

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Returns
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  • Received character
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  • =1 - No character received
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uint32_t ITM_SendChar (uint32_t ch)
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This function transmits a character via the ITM channel 0. It returns when no debugger is connected that has booked the output. It is blocking when a debugger is connected, but the previously sent character has not been transmitted.

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Parameters
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[in]chCharacter to transmit
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Returns
Character to transmit
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Variable Documentation

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volatile int32_t ITM_RxBuffer
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+ + + + -- cgit