readme_threadx.txt
1 Microsoft's Azure RTOS ThreadX for Cortex-M23
2
3 Using the GNU Tools
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5
61. Building the ThreadX run-time Library
7
8An example .bat file is in the example_build directory.
9Files tx_thread_stack_error_handler.c and tx_thread_stack_error_notify.c
10replace the common files of the same name.
11
122. Demonstration System
13
14No demonstration example is provided.
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16
173. System Initialization
18
19The entry point in ThreadX for the Cortex-M23 using gnu tools uses the standard GNU
20Cortex-M23 reset sequence. From the reset vector the C runtime will be initialized.
21
22The ThreadX tx_initialize_low_level.S file is responsible for setting up
23various system data structures, the vector area, and a periodic timer interrupt
24source.
25
26In addition, _tx_initialize_low_level determines the first available
27address for use by the application, which is supplied as the sole input
28parameter to your application definition function, tx_application_define.
29
30
314. Register Usage and Stack Frames
32
33The following defines the saved context stack frames for context switches
34that occur as a result of interrupt handling or from thread-level API calls.
35All suspended threads have the same stack frame in the Cortex-M23 version of
36ThreadX. The top of the suspended thread's stack is pointed to by
37tx_thread_stack_ptr in the associated thread control block TX_THREAD.
38
39
40 Stack Offset Stack Contents
41
42 0x00 LR Interrupted LR (LR at time of PENDSV)
43 0x04 r8
44 0x08 r9
45 0x0C r10
46 0x10 r11
47 0x14 r4
48 0x18 r5
49 0x1C r6
50 0x20 r7
51 0x24 r0 (Hardware stack starts here!!)
52 0x28 r1
53 0x2C r2
54 0x30 r3
55 0x34 r12
56 0x38 lr
57 0x3C pc
58 0x40 xPSR
59
60
615. Improving Performance
62
63To make ThreadX and the application(s) run faster, you can enable
64all compiler optimizations.
65
66In addition, you can eliminate the ThreadX basic API error checking by
67compiling your application code with the symbol TX_DISABLE_ERROR_CHECKING
68defined.
69
70
716. Interrupt Handling
72
73ThreadX provides complete and high-performance interrupt handling for Cortex-M23
74targets. There are a certain set of requirements that are defined in the
75following sub-sections:
76
77
786.1 Vector Area
79
80The Cortex-M23 vectors start at the label __tx_vectors or similar. The application may modify
81the vector area according to its needs. There is code in tx_initialize_low_level() that will
82configure the vector base register.
83
84
856.2 Managed Interrupts
86
87ISRs can be written completely in C (or assembly language) without any calls to
88_tx_thread_context_save or _tx_thread_context_restore. These ISRs are allowed access to the
89ThreadX API that is available to ISRs.
90
91ISRs written in C will take the form (where "your_C_isr" is an entry in the vector table):
92
93void your_C_isr(void)
94{
95
96 /* ISR processing goes here, including any needed function calls. */
97}
98
99ISRs written in assembly language will take the form:
100
101
102 .global your_assembly_isr
103 .thumb_func
104your_assembly_isr:
105; VOID your_assembly_isr(VOID)
106; {
107 PUSH {r0, lr}
108;
109; /* Do interrupt handler work here */
110; /* BL <your interrupt routine in C> */
111
112 POP {r0, r1}
113 MOV lr, r1
114 BX lr
115; }
116
117
118Note: the Cortex-M23 requires exception handlers to be thumb labels, this implies bit 0 set.
119To accomplish this, the declaration of the label has to be preceded by the assembler directive
120.thumb_func to instruct the linker to create thumb labels. The label __tx_IntHandler needs to
121be inserted in the correct location in the interrupt vector table. This table is typically
122located in either your runtime startup file or in the tx_initialize_low_level.S file.
123
124
1257. Revision History
126
127For generic code revision information, please refer to the readme_threadx_generic.txt
128file, which is included in your distribution. The following details the revision
129information associated with this specific port of ThreadX:
130
13106-02-2021 Release 6.1.7 changes:
132 tx_thread_secure_stack_initialize.S New file
133 tx_thread_schedule.S Added secure stack initialize to SVC hander
134 tx_thread_secure_stack.c Fixed stack pointer save, initialize in handler mode
135
13604-02-2021 Release 6.1.6 changes:
137 tx_port.h Updated macro definition
138 tx_thread_schedule.s Added low power support
139
14003-02-2021 The following files were changed/added for version 6.1.5:
141 tx_port.h Added ULONG64_DEFINED
142
14312-31-2020 The following files were
144 changed/added for port specific version 6.1.3:
145
146 tx_port.h Remove unneeded include files,
147 use builtin functions,
148 modified comments.
149
150 tx_thread_secure_stack.c Remove unneeded include file,
151 use inline get/set functions,
152 modified comments.
153
15409-30-2020 Initial ThreadX 6.1 version for Cortex-M23 using GNU tools.
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156
157Copyright(c) 1996-2020 Microsoft Corporation
158
159
160https://azure.com/rtos
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162
