PIC16F688

Manufacturer Part NumberPIC16F688
ManufacturerMicrochip Technology Inc.
PIC16F688 datasheet
 


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
117
118
119
120
121
Page 121
122
Page 122
123
Page 123
124
Page 124
125
Page 125
126
Page 126
127
Page 127
128
Page 128
129
Page 129
130
Page 130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
Page 124/202:

Context Saving During Interrupts

Download datasheet (4Mb)Embed
PrevNext
PIC16F688
11.4

Context Saving During Interrupts

During an interrupt, only the return PC value is saved
on the stack. Typically, users may wish to save key
registers during an interrupt (e.g., W and Status
registers). This must be implemented in software.
Since the lower 16 bytes of all banks are common in the
PIC16F688 (see Figure 2-2), temporary holding
registers, W_TEMP and STATUS_TEMP, should be
placed in here. These 16 locations do not require
banking and therefore, make it easier to context save
and restore. The same code shown in Example 11-1
can be used to:
• Store the W register
• Store the Status register
• Execute the ISR code
• Restore the Status (and Bank Select Bit register)
• Restore the W register
Note:
The PIC16F688 normally does not require
saving
the
PCLATH.
computed GOTO’s are used in the ISR and
the main code, the PCLATH must be
saved and restored in the ISR.
EXAMPLE 11-1:
SAVING STATUS AND W REGISTERS IN RAM
MOVWF
W_TEMP
;Copy W to TEMP register
SWAPF
STATUS,W
;Swap status to be saved into W
;Swaps are used because they do not affect the status bits
MOVWF
STATUS_TEMP
;Save status to bank zero STATUS_TEMP register
:
:(ISR)
;Insert user code here
:
SWAPF
STATUS_TEMP,W
;Swap STATUS_TEMP register into W
;(sets bank to original state)
MOVWF
STATUS
;Move W into STATUS register
SWAPF
W_TEMP,F
;Swap W_TEMP
SWAPF
W_TEMP,W
;Swap W_TEMP into W
DS41203D-page 122
However,
if
© 2007 Microchip Technology Inc.