HSP50215 데이터 시트보기 (PDF) - Intersil
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HSP50215 Datasheet PDF : 21 Pages
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HSP50215
Cascade Input
The cascade input allows multiple modulated signals to be
summed together prior to routing to a DAC. Figure 12 is a
block diagram of the cascade circuitry. CAS(15:0) is the
input when cascading with other DUC’s. The CASZ is used
to zero the CAS(15:0) input when it is not used. Both the
CAS(15:0) and the modulator data path are registered, prior
to summation. The output of the summation is saturated to
prevent roll-over.
16
CAS(15:0)
CASZ
R
E
>G
∑
SATURATE 16
CIRCUITRY
FROM
MODULATOR
† ALL REGISTERS ARE
CLOCKED AT REFLCK
16
R
E
>G
FIGURE 12. CASCADE INPUT BLOCK DIAGRAM
Output Formatter
The output can be either twos complement or offset binary
format. The OFM signal is used to select the output format.
OFM = 1 is twos complement. OFM = 0 is Offset Binary
format. The OE signal is used to enable the data bus output.
OE = 0 enables the output.
NOTE: The HSP43216 can be used to double the output sample
rate of the DUC, in applications where a higher sample
rate into the DAC is required.
Microprocessor Interface
The microprocessor interface is a memory mapped direct
access interface. The control pins are RD, WR and CE. The
10-bit address bus is A(9:0) [address space is 1024 words]
and the 16-bit data bus is C(15:0). The CE signal gates the
RD and WR. Care must be taken in changing the address
and data lines, as the addresses are updated asynchronous
to REFCLK except in the cases noted in the Microprocessor
Write Section. Most addresses are intended to be
programmed after RESET and before the Start Sequence,
and left alone after that. See the RESET and Start
Sequence sections from more details on initiating operation
of the part.
Reads are asynchronous to clock. The shaping filter
coefficients cannot be read. See the Configuration Control
Register Bit Definitions section for programming details of
the 14 Control Words and the 512 Coefficient Registers.
Microprocessor Write
The Microprocessor Write Interface is used for loading data
into the DUC control registers. Write registers are accessed
via the 10-bit address bus (A9:0) and the 16-bit data bus
(C15:0). The address map for these registers is given in the
Configuration Control Register Bit Definition section.
Configuration data is written into the HSP50215 by setting up
the address (A9:0) and data (C15:0) and generating a rising
edge on WR. A DUC configuration sequence is shown in
Figure 13. Figure 13 assumes that CE is asserted. The filter
coefficients for the shaping filter are loaded in a similar
manner into Control Word addresses 512 - 1023.
WR
A(10:0) 2 3 4 5 16 17 18 19 22 23
C(15:0)
LOAD CONFIGURATION DATA
FIGURE 13. CONTROL REGISTER LOADING SEQUENCE
The Re-Sampler NCO Center Frequency data is double
buffered and transfers from the Microprocessor Interface
holding registers to the Center Frequency Register on the
assertion of SYNCIN or a Write to Configuration Control
Word 3. The timing waveforms for this process are shown in
Figure 14.
REFCLK
WR
SYNCIN
A0-2
02
03
C0-7
MSB
LSB
CW02
MSB
CW03
LSB
SR(29:0)
NEW SR
VALUE
FIGURE 14. RESAMPLER CENTER FREQUENCY CONTROL
REGISTER LOADING SEQUENCE
When SYNCIN is sampled “high” by the rising edge of clock,
the contents of the holding registers are transferred to the
Sample Center Frequency Register. Caution should be
taken when using the SYNCIN since the holding register
contents will be transferred to the Sample Center Frequency
Register whenever SYNCIN is asserted (and external sync
is selected via CW22).
Shaping filter I coefficients are loaded from the first coefficient
(C0) in address 0x200h to the last address in 0x2FFh.
Because interpolation by 16 is possible, the coefficient
addresses are structured in blocks of 16, one address for
each phase of the interpolation. With a 256 tap filter using an
interpolation of 16, there are 16 multiplies required to
implement the filter. Tables 4 and 5 detail the coefficient
address allocation, with the Interpolation Phase indicated by
the IP number on the left, and the multiplier number
indicated by the numbers 0 through 15 across the top.
3-432
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