DSPIC30F2010-30I/SP Microchip Technology, DSPIC30F2010-30I/SP Datasheet - Page 33

• Manufacturer Part Number: DSPIC30F2010-30I/SP
• Description: IC DSPIC MCU/DSP 12K 28DIP
• Manufacturer: Microchip Technology
• Series: dsPIC™ 30Fr

Specifications of DSPIC30F2010-30I/SP

• Core Processor: dsPIC
• Core Size: 16-Bit
• Speed: 30 MIPs
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, Motor Control PWM, QEI, POR, PWM, WDT
• Number Of I /o: 20
• Program Memory Size: 12KB (4K x 24)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.5 V ~ 5.5 V
• Data Converters: A/D 6x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Core Frequency: 40MHz
• Core Supply Voltage: 5.5V
• Embedded Interface Type: I2C, SPI, UART
• No. Of I/o's: 20
• Flash Memory Size: 12KB
• Supply Voltage Range: 2.5V To 5.5V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: DV164005 - KIT ICD2 SIMPLE SUIT W/USB CABLE
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: DSPIC30F2010-30I; DSPIC30F2010-30I; DSPIC30F2010-30I/SPG; DSPIC30F201030ISP

4.2
Modulo addressing is a method of providing an auto-
mated means to support circular data buffers using
hardware. The objective is to remove the need for soft-
ware 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 only be
configured to operate in one direction, as there are
certain restrictions on the buffer start address (for
incrementing buffers) or end address (for decrementing
buffers) based upon the direction of the buffer.
The only exception to the usage restrictions is for
buffers which have a power-of-2 length. As these
buffers satisfy the start and end address criteria, they
may operate in a Bidirectional mode, (i.e., address
boundary checks will be performed on both the lower
and upper address boundaries).
© 2011 Microchip Technology Inc.
Modulo Addressing
4.2.1
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
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
possible length of the circular buffer is 32K words
(64 Kbytes).
4.2.2
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
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:
Table
3-3).
START AND END ADDRESS
Y space Modulo Addressing EA calcula-
tions assume word-sized data (LSb of
every EA is always clear).
W ADDRESS REGISTER
SELECTION
dsPIC30F2010
Table
3-3). Modulo addressing is
DS70118J-page 33