DSPIC30F6010_06 datasheet(35/222 Pages) MICROCHIP

35 / 222 page

DS70119E-page 33

dsPIC30F6010

4.2.1

START AND END ADDRESS

The Modulo Addressing scheme requires that a

starting and an end address be specified and loaded

into the 16-bit modulo buffer address registers:

XMODSRT, XMODEND, YMODSRT and YMODEND

(see Table 3-3)..

The length of a circular buffer is not directly specified. It

is determined by the difference between the corre-

sponding start and end addresses. The maximum pos-

sible length of the circular buffer is 32K words

(64 Kbytes).

4.2.2

W ADDRESS REGISTER

SELECTION

The Modulo and Bit-Reversed Addressing Control reg-

ister MODCON<15:0> contains enable flags as well as

a W register field to specify the W address registers.

The XWM and YWM fields select which registers will

operate with Modulo Addressing. If XWM = 15, X

RAGU and X WAGU Modulo Addressing are disabled.

Similarly, if YWM = 15, Y AGU Modulo Addressing is

disabled.

The X Address Space Pointer W register (XWM) to

which Modulo Addressing is to be applied, is stored in

MODCON<3:0> (see Table 3-3). Modulo Addressing is

enabled for X data space when XWM is set to any value

other than 15 and the XMODEN bit is set at

MODCON<15>.

The Y Address Space Pointer W register (YWM) to

which Modulo Addressing is to be applied, is stored in

MODCON<7:4>. Modulo Addressing is enabled for Y

data space when YWM is set to any value other than 15

and the YMODEN bit is set at MODCON<14>.

FIGURE 4-1:

MODULO ADDRESSING OPERATION EXAMPLE

Note:

Y-space Modulo Addressing EA calcula-

tions assume word-sized data (LSb of

every EA is always clear).

0x1100

0x1163

Start Addr = 0x1100

End Addr = 0x1163

Length = 0x0032 words

Byte

Address

MOV

#0x1100,W0

MOV

W0, XMODSRT

;set modulo start address

MOV

#0x1163,W0

MOV

W0,MODEND

;set modulo end address

MOV

#0x8001,W0

MOV

W0,MODCON

;enable W1, X AGU for modulo

MOV

#0x0000,W0

;W0 holds buffer fill value

MOV

#0x1110,W1

;point W1 to buffer

AGAIN,#0x31

;fill the 50 buffer locations

MOV

W0, [W1++]

;fill the next location

AGAIN:

INC

W0,W0

;increment the fill value

DSPIC30F6010 Folha de dados(PDF) 35 Page - Microchip Technology

DSPIC30F6010 Folha de dados(HTML) 35 Page - Microchip Technology

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

Folha de dados Download

Ligação URL