| 206 |
Kevin |
1 |
#include <xc.h>
|
|
|
2 |
#include <plib.h>
|
|
|
3 |
#include "defines.h"
|
|
|
4 |
#include "TIMER4.h"
|
|
|
5 |
|
|
|
6 |
static TIMER4_DATA *timer_data_ptr;
|
|
|
7 |
|
|
|
8 |
void TIMER4_Init(TIMER4_DATA *data, void (*callback)(void), unsigned int time_us) {
|
|
|
9 |
if (data != NULL) // if ptr is null, use existing data
|
|
|
10 |
timer_data_ptr = data;
|
|
|
11 |
|
|
|
12 |
timer_data_ptr->callback_function = callback;
|
|
|
13 |
|
|
|
14 |
INTDisableInterrupts();
|
|
|
15 |
|
|
|
16 |
T4CON = 0x0;
|
|
|
17 |
|
|
|
18 |
// PR5 is 16 bits wide, so we need to determine what pre-scaler to use
|
|
|
19 |
int time;
|
|
|
20 |
if (time_us < 13107) {
|
|
|
21 |
time = 5 * time_us;
|
|
|
22 |
T4CONSET = 0x0040; // Prescaler at 1:16
|
|
|
23 |
} else if (time_us < 26214) {
|
|
|
24 |
time = 2.5 * time_us;
|
|
|
25 |
T4CONSET = 0x0050; // Prescaler at 1:32
|
|
|
26 |
} else if (time_us < 52428) {
|
|
|
27 |
time = 1.25 * time_us;
|
|
|
28 |
T4CONSET = 0x0060; // Prescaler at 1:64
|
| 207 |
Kevin |
29 |
} else {
|
|
|
30 |
time = 0.3125 * time_us; // Minimum time_us of 209712
|
| 206 |
Kevin |
31 |
T4CONSET = 0x0070; // Prescaler at 1:256
|
|
|
32 |
}
|
|
|
33 |
|
|
|
34 |
Nop();
|
|
|
35 |
TMR4 = 0x0; // Clear timer register
|
|
|
36 |
PR4 = time; // Load period register
|
|
|
37 |
IPC4SET = 0x00000011; // Set priority level = 4, sub-priority level = 1
|
|
|
38 |
IFS0CLR = 0x00010000; // Clear timer interrupt flag
|
|
|
39 |
IEC0SET = 0x00010000; // Enable timer interrupt
|
|
|
40 |
|
|
|
41 |
INTEnableInterrupts();
|
|
|
42 |
}
|
|
|
43 |
|
|
|
44 |
void TIMER4_Start(void) {
|
|
|
45 |
T4CONSET = 0x8000; // Start timer
|
|
|
46 |
}
|
|
|
47 |
|
|
|
48 |
void TIMER4_Stop(void) {
|
|
|
49 |
T4CONCLR = 0x8000; // Stop timer
|
|
|
50 |
}
|
|
|
51 |
|
|
|
52 |
void __ISR(_TIMER_4_VECTOR, ipl4) __TIMER_4_Interrupt_Handler(void) {
|
|
|
53 |
// Call the saved callback function
|
|
|
54 |
(*timer_data_ptr->callback_function)();
|
|
|
55 |
|
|
|
56 |
IFS0CLR = 0x00010000; // Clear the timer interrupt flag
|
|
|
57 |
}
|