DSPIC33FJ16MC304-E/PT Microchip Technology, DSPIC33FJ16MC304-E/PT Datasheet - Page 50

• Manufacturer Part Number: DSPIC33FJ16MC304-E/PT
• Description: 16-bit DSC, 16KB Flash,Motor,40 MIPS,nanoWatt 44 TQFP 10x10x1mm TRAY
• Manufacturer: Microchip Technology
• Series: dsPIC™ 33Fr

Specifications of DSPIC33FJ16MC304-E/PT

• Core Processor: dsPIC
• Core Size: 16-Bit
• Speed: 40 MIPs
• Connectivity: I²C, IrDA, LIN, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, DMA, Motor Control PWM, QEI, POR, PWM, WDT
• Number Of I /o: 35
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 9x10b/12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: DM240001 - BOARD DEMO PIC24/DSPIC33/PIC32
• Eeprom Size: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: DSPIC33FJ16MC304-E/PTTR; DSPIC33FJ16MC304-E/PTTR

dsPIC33FJ32MC202/204 and dsPIC33FJ16MC304
4.4
Modulo Addressing mode is a method of providing an
automated means to support circular data buffers using
hardware. The objective is to remove the need for
software to perform data address boundary checks
when executing tightly looped code, as is typical in
many DSP algorithms.
Modulo Addressing can operate in either data or program
space (since the data pointer mechanism is essentially
the same for both). One circular buffer can be supported
in each of the X (which also provides the pointers into
program space) and Y data spaces. Modulo Addressing
can operate on any W register pointer. However, it is not
advisable to use W14 or W15 for Modulo Addressing
since these two registers are used as the Stack Frame
Pointer and Stack Pointer, respectively.
In general, any particular circular buffer can be
configured to operate in only one direction as there are
certain restrictions on the buffer start address (for incre-
menting buffers), or end address (for decrementing
buffers), based upon the direction of the buffer.
The only exception to the usage restrictions is for
buffers that have a power-of-two length. As these
buffers satisfy the start and end address criteria, they
can operate in a bidirectional mode (that is, address
boundary checks are performed on both the lower and
upper address boundaries).
4.4.1
The Modulo Addressing scheme requires that a
starting and ending address be specified and loaded
into the 16-bit Modulo Buffer Address registers:
XMODSRT, XMODEND, YMODSRT and YMODEND
(see
FIGURE 4-5:
DS70283H-page 50
Table
Address
0x1100
0x1163
Byte
Modulo Addressing
4-1).
START AND END ADDRESS
Start Addr = 0x1100
End Addr = 0x1163
Length = 0x0032 words
MODULO ADDRESSING OPERATION EXAMPLE
MOV
MOV
MOV
MOV
MOV
MOV
MOV
MOV
DO
MOV
AGAIN: INC W0, W0
#0x1100, W0
W0, XMODSRT
#0x1163, W0
W0, MODEND
#0x8001, W0
W0, MODCON
#0x0000, W0
#0x1110, W1
AGAIN, #0x31
W0, [W1++]
The length of a circular buffer is not directly specified. It
is
corresponding start and end addresses. The maximum
possible length of the circular buffer is 32K words
(64 Kbytes).
4.4.2
The Modulo and Bit-Reversed Addressing Control
register, 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 the registers that will
operate with Modulo Addressing:
• If XWM = 15, X RAGU and X WAGU Modulo
• If YWM = 15, Y AGU Modulo Addressing is
The X Address Space Pointer W register (XWM), to
which Modulo Addressing is to be applied, is stored in
MODCON<3:0> (see
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>.
Note:
Addressing is disabled.
disabled.
determined
;set modulo start address
;set modulo end address
;enable W1, X AGU for modulo
;W0 holds buffer fill value
;point W1 to buffer
;fill the 50 buffer locations
;fill the next location
;increment the fill value
Y
calculations assume word-sized data
(LSb of every EA is always clear).
W ADDRESS REGISTER
SELECTION
space
by
Table
the
© 2011 Microchip Technology Inc.
Modulo
4-1). Modulo Addressing is
difference
Addressing
between
EA
the