Add RXv1 port.
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Tiejun Zhou
164
ports/rxv1/ccrx/readme_threadx.txt
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164
ports/rxv1/ccrx/readme_threadx.txt
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Microsoft's Azure RTOS ThreadX for Renesas RXv1
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Using the CC-RX Tools
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1. Building the ThreadX run-time Library
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Please see the Samples repository on GitHub for the Azure RTOS demonstrations
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for the RXv1.
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2. Demonstration System
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Please see the Samples repository on GitHub for the Azure RTOS demonstrations
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for the RXv1
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3. System Initialization
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The system entry point using Renesas tools is at the label _PowerON_Reset_PC.
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Use the resetprg.c file that comes with your release. Most notable is that Threadx
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applications run in supervisor mode and do not use user mode. Hence switching to
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user mode has been commented out.
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The vector area is set up using either intprg.c or in the file tx_initialize_low_level.src.
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The file tx_initialize_low_level.src is responsible for setting up various system data
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structures, interrupt vectors, and a periodic timer. This is the ideal place add
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application specific hardware initialization code.
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ThreadX utilizes CMT0 as a periodic timer interrupt source. The CMT0 interrupt is
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typically setup for 10ms periodic interrupts and the interrupt priority level is set to
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level 7. You may change any of the timer parameters to suit your needs.
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In addition, _tx_initialize_low_level determines the first available address for use by
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the application, which is supplied as the sole input parameter to your application
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definition function, tx_application_define(). The mechanism is implemented by creating the
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FREEMEM section, this section should be linked last in the RAM area. tx_initialize_low_level
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will pick up the starting label of this section and put it in the global variable:
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_tx_initialize_unused_memory
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4. Context Switch, Register Usage and Stack Frames
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The RXv1 port for ThreadX uses the first software interrupt, SWINT, i.e., interrupt #17,
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to perform context switch. This ISR is thus reserved when using ThreadX and the SWINT
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should not be manipulated in any way by the application. The port will setup the
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interrupt within _tx_initialize_low_level and the compiler will automatically install
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the necessary interrupt vector. As such no additional initialization is necessary by the
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application.
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The following defines the saved context stack frame used by the ThreadX port. The
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state of the CPU registers at the time of a context switch is saved on the running
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thread's stack The top of the suspended thread's stack is pointed to by
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tx_thread_stack_ptr in the associated thread control block TX_THREAD.
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Offset Interrupted Stack Frame
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0x00 1
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0x04 ACC0
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0x0C R6
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0x10 R7
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0x14 R8
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0x18 R9
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0x1C R10
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0x20 R11
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0x24 R12
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0x28 R13
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0x30 R14
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0x34 R15
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0x38 R3
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0x3C R4
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0x40 R5
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0x44 R1
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0x48 R2
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0x4C PC - return address
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0x50 PSW
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Note: By default ccrx does not save the state of the accumulator register ACC0
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when entering an ISR. This means that if the ISR uses any of the DSP instructions the
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content of the register could be corrupted. Saving and restoring of the accumulator
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can be enabled by adding the -save_acc command line option.
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5. Improving Performance
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The distribution version of ThreadX is built without any compiler
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optimizations. This makes it easy to debug because you can trace or set
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breakpoints inside of ThreadX itself. Of course, this costs some
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performance. To make ThreadX run faster, you can change the ThreadX Library
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project to disable debug information and enable the desired optimizations.
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In addition, you can eliminate the ThreadX basic API error checking by
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compiling your application code with the symbol TX_DISABLE_ERROR_CHECKING
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defined before tx_api.h is included.
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6. Timer Processing
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Timer processign is performed by calling __tx_timer_interrupt(). This should usually be done
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from within the callback of a periodic timer with a period of 100Hz. In the sample projects
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a Renesas Fit CMT periodic timer module (rx_cmt) is used as the timer source.
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7. Interrupt Handling
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Interrupt handling is unaffected by the ThreadX port as such user interrupts can be
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written according to the toolchain's documentation. It is recommended not to use interrupt
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priority 15 as this is the priority of the context switch interrupt. However using interrupt
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priority 15 won't cause any negative side effectd but doing so may may slightly reduce
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performance. Please refer to the toolchain documentation for additional details on how to
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define interupt service routines.
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8. Execution Profiling
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The RX port adds support for the Execution Profiling Kit (EPK). The EPK consists
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of the files tx_execution_profile.c and tx_execution_profile.h. See the documentation
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of the EPK for generic usage details.
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To add the EPK to your RXv1 release make the following modifications:
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* Enable the following define for both the Threadx library and the application
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TX_EXECUTION_PROFILE_ENABLE
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* Setup CMT1 as a free running 16 bit timer.
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* In tx_execution_profile.h, change following around line 52:
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#ifdef TX_EXECUTION_64BIT_TIME
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typedef unsigned long long EXECUTION_TIME;
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#define TX_EXECUTION_MAX_TIME_SOURCE 0xFFFFFFFFFFFFFFFF
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#else
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typedef unsigned long EXECUTION_TIME;
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#define TX_EXECUTION_MAX_TIME_SOURCE 0xFFFF
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#endif
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/* Define basic constants for the execution profile kit. */
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#define TX_EXECUTION_TIME_SOURCE (EXECUTION_TIME) *((USHORT *) 0x8800A)
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Rebuild the Threadx library and the application.
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Refer to the EPK documentation how to interpret the results.
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9. Revision History
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For generic code revision information, please refer to the readme_threadx_generic.txt
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file, which is included in your distribution. The following details the revision
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information associated with this specific port of ThreadX:
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For generic code revision information, please refer to the readme_threadx_generic.txt
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file, which is included in your distribution. The following details the revision
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information associated with this specific port of ThreadX:
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08-02-2021 Initial ThreadX release for the RXv1 using CC-RXX tools, version 6.1.8
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Copyright(c) 1996-2021 Microsoft Corporation
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https://azure.com/rtos
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www.expresslogic.com
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