1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
/*
* Copyright (c) 2020-2021 Arm Limited. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/****************************************************************************
* Includes
****************************************************************************/
#include "tx_api.h"
#include <stdio.h>
/****************************************************************************
* Defines
****************************************************************************/
#define SYSTEM_CLOCK 6000000
#define SYSTICK_CYCLES ((SYSTEM_CLOCK / 100) - 1)
/****************************************************************************
* Externs
****************************************************************************/
void _tx_timer_interrupt(void);
/****************************************************************************
* Functions
****************************************************************************/
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _tx_initialize_low_level Cortex-M4/GNU */
/* 6.1 */
/* */
/* DESCRIPTION */
/* */
/* This function is responsible for any low-level processor */
/* initialization, including setting up interrupt vectors, setting */
/* up a periodic timer interrupt source, saving the system stack */
/* pointer for use in ISR processing later, and finding the first */
/* available RAM memory address for tx_application_define. */
/* this function has an empty implementation in this example. */
/* */
/* INPUT */
/* */
/* None */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* CALLS */
/* */
/* None */
/* */
/* CALLED BY */
/* */
/* _tx_initialize_kernel_enter ThreadX entry function */
/* */
/**************************************************************************/
VOID _tx_initialize_low_level(VOID) {
__asm__ volatile(
/* Disable interrupts during ThreadX initialization. */
" CPSID i\n"
/* Enable the cycle count register. */
" LDR r0, =0xE0001000\n" // Build address of DWT register
" LDR r1, [r0]\n" // Pickup the current value
" ORR r1, r1, #1\n" // Set the CYCCNTENA bit
" STR r1, [r0]\n" // Enable the cycle count register
/* Configure SysTick for 100Hz clock, or 16384 cycles if no reference. */
" MOV r0, #0xE000E000\n" // Build address of NVIC registers
" LDR r1, =59999\n" // 59,999 = SYSTICK_CYCLES = ((6,000,000 / 100) -1)
" STR r1, [r0, #0x14]\n" // Setup SysTick Reload Value
" MOV r1, #0x7\n" // Build SysTick Control Enable Value
" STR r1, [r0, #0x10]\n" // Setup SysTick Control
/* Configure handler priorities. */
" LDR r1, =0x00000000\n" // Rsrv, UsgF, BusF, MemM
" STR r1, [r0, #0xD18]\n" // Setup System Handlers 4-7 Priority Registers
" LDR r1, =0xFF000000\n" // SVCl, Rsrv, Rsrv, Rsrv
" STR r1, [r0, #0xD1C]\n" // Setup System Handlers 8-11 Priority Registers
// Note: SVC must be lowest priority, which is 0xFF
" LDR r1, =0x40FF0000\n" // SysT, PnSV, Rsrv, DbgM
" STR r1, [r0, #0xD20]\n" // Setup System Handlers 12-15 Priority Registers
// Note: PnSV must be lowest priority, which is 0xFF
/* Return to caller. */
" BX lr\n");
}
/* SysTick_Handler has a generic interrupt handler template. */
/* to implement a new handler, replace the call to */
/* _tx_timer_interrupt to some other c function */
VOID SysTick_Handler(VOID) {
#ifdef TX_ENABLE_EXECUTION_CHANGE_NOTIFY
_tx_execution_isr_enter(); // Call the ISR enter function
#endif
_tx_timer_interrupt();
#ifdef TX_ENABLE_EXECUTION_CHANGE_NOTIFY
_tx_execution_isr_exit(); // Call the ISR exit function
#endif
return;
}
|
