DSPIC30F2012-20I/SP Microchip Technology, DSPIC30F2012-20I/SP Datasheet - Page 46

• Manufacturer Part Number: DSPIC30F2012-20I/SP
• Description: IC DSPIC MCU/DSP 12K 28DIP
• Manufacturer: Microchip Technology
• Series: dsPIC™ 30Fr

Specifications of DSPIC30F2012-20I/SP

• Core Processor: dsPIC
• Core Size: 16-Bit
• Speed: 20 MIPS
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 20
• Program Memory Size: 12KB (4K x 24)
• Program Memory Type: FLASH
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.5 V ~ 5.5 V
• Data Converters: A/D 10x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Core Frequency: 40MHz
• Embedded Interface Type: I2C, SPI, UART
• No. Of I/o's: 20
• Flash Memory Size: 12KB
• Supply Voltage Range: 2.5V To 5.5V
• Operating Temperature Range: -40°C To
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: DSPIC30F201220ISP

dsPIC30F2011/2012/3012/3013
4.2.3
Modulo addressing can be applied to the effective
address (EA) calculation associated with any W regis-
ter. It is important to realize that the address bound-
aries check for addresses less than, or greater than the
upper (for incrementing buffers), and lower (for decre-
menting buffers) boundary addresses (not just equal
to). Address changes may, therefore, jump beyond
boundaries and still be adjusted correctly.
4.3
Bit-reversed addressing 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.
4.3.1
Bit-reversed addressing is enabled when:
1.
2.
3.
DS70139C-page 44
Note:
BWM (W register selection) in the MODCON
register is any value other than ‘15’ (the stack
cannot
addressing) and
the BREN bit is set in the XBREV register and
the addressing mode used is Register Indirect
with Pre-Increment or Post-Increment.
Bit-Reversed Addressing
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 correction is per-
formed but the contents of the register
remain unchanged.
BIT-REVERSED ADDRESSING
IMPLEMENTATION
be
accessed
using
bit-reversed
Preliminary
If the length of a bit-reversed buffer is M = 2
then 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 will only be
executed 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 will be gener-
ated instead. When bit-reversed addressing is active,
the W address pointer will always be added to the
address modifier (XB) and the offset associated with
the Register Indirect Addressing mode will be ignored.
In addition, as word sized data is a requirement, the LS
bit 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 (LS bit of every EA is
always clear). The XB value is scaled
accordingly to generate compatible (byte)
addresses.
Modulo
addressing should not be enabled together.
In the event that the user attempts to do
this, bit-reversed addressing will assume
priority when active for the X WAGU, and X
WAGU modulo addressing will be disabled.
However, modulo addressing will continue
to function in the X RAGU.
addressing
© 2005 Microchip Technology Inc.
and
bit-reversed
N
bytes,