MA330013 Microchip Technology, MA330013 Datasheet - Page 72

• Manufacturer Part Number: MA330013
• Description: MODULE PLUG-IN DSPIC33 100TQFP
• Manufacturer: Microchip Technology

Specifications of MA330013

• Accessory Type: Plug-In Module (PIM) - dsPIC33FJ256MC710
• Tool / Board Applications: General Purpose MCU, MPU, DSP, DSC
• Mcu Supported Families: DsPIC33
• Silicon Manufacturer: Microchip
• Core Architecture: DsPIC
• Core Sub-architecture: DsPIC33
• Silicon Core Number: DsPIC33F
• Silicon Family Name: DsPIC33FJxxMCxxx
• Rohs Compliant: Yes
• For Use With: DM330023 - BOARD DEV DSPICDEM MCHV
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: Explorer 16 (DM240001 or DM240002)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Not applicable / Not applicable

dsPIC33F
3.4.3
Modulo Addressing can be applied to the Effective
Address (EA) calculation associated with any W
register. It is important to realize that the address
boundaries check for addresses less than, or greater
than, the upper (for incrementing buffers) and lower (for
decrementing buffers) boundary addresses (not just
equal to). Address changes may, therefore, jump
beyond boundaries and still be adjusted correctly.
3.5
Bit-Reversed Addressing mode is intended to simplify
data re-ordering for radix-2 FFT algorithms. It is
supported by the X AGU for data writes only.
The modifier, which may be a constant value or register
contents, is regarded as having its bit order reversed. The
address source and destination are kept in normal order.
Thus, the only operand requiring reversal is the modifier.
3.5.1
Bit-Reversed Addressing mode is enabled when:
1.
2.
3.
DS70165E-page 70
Note:
BWM bits (W register selection) in the
MODCON register are any value other than ‘15’
(the
Bit-Reversed Addressing).
The BREN bit is set in the XBREV register.
The addressing mode used is Register Indirect
with Pre-Increment or Post-Increment.
Bit-Reversed Addressing
stack
MODULO ADDRESSING
APPLICABILITY
The modulo corrected effective address is
written back to the register only when
Pre-Modify or Post-Modify Addressing
mode is used to compute the effective
address. When an address offset (e.g.,
[W7+W2]) is used, Modulo Address cor-
rection is performed but the contents of
the register remain unchanged.
BIT-REVERSED ADDRESSING
IMPLEMENTATION
cannot
be
accessed
using
Preliminary
If the length of a bit-reversed buffer is M = 2
the last ‘N’ bits of the data buffer start address must
be zeros.
XB<14:0> is the Bit-Reversed Address modifier, or
‘pivot point’, which is typically a constant. In the case of
an FFT computation, its value is equal to half of the FFT
data buffer size.
When enabled, Bit-Reversed Addressing is only exe-
cuted for Register Indirect with Pre-Increment or
Post-Increment Addressing and word sized data writes.
It will not function for any other addressing mode or for
byte sized data and normal addresses are generated
instead. When Bit-Reversed Addressing is active, the
W Address Pointer is always added to the address
modifier (XB) and the offset associated with the Regis-
ter Indirect Addressing mode is ignored. In addition, as
word sized data is a requirement, the LSb of the EA is
ignored (and always clear).
If Bit-Reversed Addressing has already been enabled
by setting the BREN (XBREV<15>) bit, then a write to
the XBREV register should not be immediately followed
by an indirect read operation using the W register that
has been designated as the bit-reversed pointer.
Note:
Note:
All bit-reversed EA calculations assume
word sized data (LSb of every EA is
always clear). The XB value is scaled
accordingly to generate compatible (byte)
addresses.
Modulo Addressing and Bit-Reversed
Addressing
together. In the event that the user attempts
to do so, Bit-Reversed Addressing will
assume priority when active for the X
WAGU and X WAGU Modulo Addressing
will
Addressing will continue to function in the X
RAGU.
be
disabled.
© 2007 Microchip Technology Inc.
should
However,
not
be
enabled
N
Modulo
bytes,