ST9 datasheet(19/146 Pages) STMICROELECTRONICS

19 / 146 page

19/146

ST9 USER GUIDE

inc R19

; increment the same register again

The following table summarizes the use of the srp instruction and its effect in terms of group

selection.

Table 1.

Notes:

Though it is possible, it normally makes no sense to set the working register group either to

group E (14) or F (15), since the registers in these groups have pre-defined meanings. You can-

not use them to store intermediate values of calculations without greatly affecting the behavior

of the microcontroller in an unpredictable way. However, bit-level instructions are only available

using working register addressing, so when you need to do bit manipulations in these groups,

setting the register pointer to either 28 or 30 is an efficient way of programming when accessing

these two groups.

The srp instruction is the only one you have to use to switch register groups, and is the way

working registers are used in most programs. However, the working register scheme includes

a subtlety that is seldom used, but that could give you even more flexibility in some cases. This

is what is described in the next paragraph.

The same register group number can be selected by an odd or even number. In fact, the for-

mula is:

srp

2*n+1

; for group n

srp

2*n

; for group n

Hexadecimal

number

Decimal

number

Function

decimal

(hexadecimal)

srp #n

instruction to select a

group to provide r0-r15

F0-FF

240-255

Paged registers

15 (F)

srp #30

E0-EF

224-239

System registers

14 (E)

srp #28

D0-DF

208-223

General

purpose

registers

13 (D)

srp #26

C0-CF

192-207

12 (C)

srp #24

B0-BF

176-191

11 (B)

srp #22

A0-AF

160-175

10 (A)

srp #20

90-9F

144-159

srp #18

80-8F

128-143

srp #16

70-7F

112-127

srp #14

60-6F

96-111

srp #12

50-5F

80-95

srp #10

40-4F

64-79

srp #8

30-3F

48-63

srp #6

20-2F

32-47

srp #4

10-1F

16-31

srp #2

00-0F

00-15

srp #0

ST9 Datasheet(PDF) 19 Page - STMicroelectronics

ST9 Datasheet(HTML) 19 Page - STMicroelectronics

Html Pages

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 ...More

Datasheet Download

Link URL