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AD7265
Rev. A | Page 24 of 28
AD7265 to ADSP-BF53x
AD7265 TO TMS320C541
The ADSP-BF53x family of DSPs interface directly to the
AD7265 without any glue logic required. The availability of
secondary receive registers on the serial ports of the Blackfin
DSPs means only one serial port is necessary to read from both
D
The serial interface on the TMS320C541 uses a continuous
serial clock and frame synchronization signals to synchronize
the data transfer operations with peripheral devices like the
AD7265. The CS input allows easy interfacing between the
TMS320C541 and the AD7265 without any glue logic required.
The serial ports of the TMS320C541 are set up to operate in
burst mode with internal CLKX0 (TX serial clock on Serial
Port 0) and FSX0 (TX frame sync from Serial Port 0). The serial
port control registers (SPC) must have the following setup.
OUT
pins simultaneously. Figure 44 shows both DOUTA and DOUTB of the AD7265 connected to Serial Port 0 of the
ADSP-BF53x. The SPORT0 Receive Configuration 1 register
and SPORT0 Receive Configuration 2 register should be set up
SERIAL
DEVICE A
(PRIMARY)
SERIAL
DEVICE B
(SECONDARY)
DOUTA
CS
SCLK
ADSP-BF53x1
1ADDITIONAL PINS OMITTED FOR CLARITY.
DR0PRI
DR0SEC
RFS0
VDRIVE
VDD
DOUTB
RCLK0
04674-037
SPORT0
AD72651
Table 11. Serial Port Control Register Setup
SPC
FO
FSM
MCM
TXM
SPC0
0
1
SPC1
0
1
0
The format bit, FO, may be set to 1 to set the word length to
8 bits to implement the power-down modes on the AD7265.
The connection diagram is shown in
Figure 45. For signal
processing applications, it is imperative that the frame
synchronization signal from the TMS320C541 provide
equidistant sampling. The VDRIVE pin of the AD7265 takes the
same supply voltage as that of the TMS320C541. This allows the
ADC to operate at a higher voltage than its serial interface, and
therefore, the TMS320C541, if necessary.
Figure 44. Interfacing the AD7265 to the ADSP-BF53x
Table 9. The SPORT0 Receive Configuration 1 Register
(SPORT0_RCR1)
Setting
Description
FSR1
FSR0
SCLK
TMS320C5411
1ADDITIONAL PINS OMITTED FOR CLARITY.
CLKX0
DR1
CLKR1
CLKX1
DOUTB
DOUTA
VDRIVE
VDD
CS
FSX0
DR0
CLKR0
04674-038
AD72651
RCKFE = 1
Sample data with falling edge of RSCLK
LRFS = 1
Active low frame signal
RFSR = 1
Frame every word
IRFS = 1
Internal RFS used
RLSBIT = 0
Receive MSB first
RDTYPE = 00
Zero fill
IRCLK = 1
Internal receive clock
RSPEN = 1
Receive enabled
16-bit data-word (or may be set to 1101
for 14-bit data-word)
SLEN = 1111
TFSR = RFSR = 1
Table 10. The SPORT0 Receive Configuration 2 Register
(SPORT0_RCR2)
Figure 45. Interfacing the AD7265 to the TMS320C541
Setting
Description
RXSE = 1
Secondary side enabled
SLEN = 1111
16-bit data-word (or may be set to 1101
for 14-bit data-word)
To implement the power-down modes, SLEN should be set to
1001 to issue an 8-bit SCLK burst. A Blackfin driver for the