AD7719BR-REEL7 Analog Devices Inc, AD7719BR-REEL7 Datasheet - Page 29

• Manufacturer Part Number: AD7719BR-REEL7
• Description: IC ADC 16BIT 24BIT DUAL 28-SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD7719BR-REEL7

• Rohs Status: RoHS non-compliant
• Number Of Bits: 16/24
• Sampling Rate (per Second): 105
• Data Interface: DSP, MICROWIRE™, QSPI™, Serial, SPI™
• Number Of Converters: 2
• Power Dissipation (max): 4.5mW
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (0.300", 7.50mm Width)
• For Use With: EVAL-AD7719EB - BOARD EVAL FOR AD7719

AD7719-to-68HC11 Interface
Figure 12 shows an interface between the AD7719 and the 68HC11
microcontroller. The diagram shows the minimum (3-wire) inter-
face with CS on the AD7719 hardwired low. In this scheme, the
RDY bits of the Status register are monitored to determine
when the Data register is updated. RDY0 indicates the status of
the main ADC channel while RDY1 indicates the status of the
aux channel. An alternative scheme, which increases the number
of interface lines to four, is to monitor the RDY output line
from the AD7719. The monitoring of the RDY line can be done in
two ways. First, RDY can be connected to one of the 68HC11’s
port bits (such as PC0), which is configured as an input. This
port bit is then polled to determine the status of RDY. The
second scheme is to use an interrupt driven system, in which case
the RDY output is connected to the IRQ input of the 68HC11. For
interfaces that require control of the CS input on the AD7719,
one of the port bits of the 68HC11 (such as PC1) that is
configured as an output, can be used to drive the CS input.
The 68HC11 is configured in the master mode with its CPOL
bit set to a logic 1 and its CPHA bit set to a logic 1. When the
68HC11 is configured like this, its SCLK line idles high between
data transfers. The AD7719 is not capable of full duplex opera-
tion. If the AD7719 is configured for a write operation, no data appears
on the DOUT lines even when the SCLK input is active. Simi-
larly, if the AD7719 is configured for a read operation, data
presented to the part on the DIN line is ignored even when
SCLK is active.
REV. A
Figure 12. AD7719-to-68HC11 Interface
68HC11
MISO
MOSI
SCK
SS
V
DD
V
DD
DOUT
RESET
SCLK
DIN
CS
AD7719
–29–
AD7719-to-8xC51 Interface
An interface circuit between the AD7719 and the 8xC51 microcon-
troller is shown in Figure 13. The diagram shows the minimum
number of interface connections with CS on the AD7719 hard-
wired low. In the case of the 8xC51 interface, the minimum
number of interconnects is just two. In this scheme, the RDY
bits of the Status register are monitored to determine when the
Data register is updated. The alternative scheme, which increases
the number of interface lines to three, is to monitor the RDY output
line from the AD7719. The monitoring of the RDY line can be
done in two ways. First, RDY can be connected to one of the
8xC51’s port bits (such as P1.0) that is configured as an input.
This port bit is then polled to determine the status of RDY.
The second scheme is to use an interrupt-driven system, in which
case the RDY output is connected to the INT1 input of the
8xC51. For interfaces that require control of the CS input on
the AD7719, one of the port bits of the 8xC51 (such as P1.1)
that is configured as an output can be used to drive the CS
input. The 8xC51 is configured in its Mode 0 serial interface
mode. Its serial interface contains a single data line. As a result,
the DOUT and DIN pins of the AD7719 should be connected
together with a 10 kΩ pull-up resistor. The serial clock on the
8xC51 idles high between data transfers. The 8xC51 outputs the
LSB first in a write operation, while the AD7719 expects the
MSB first so the data to be transmitted has to be rearranged
before being written to the output serial register. Similarly, the
AD7719 outputs the MSB first during a read operation while
the 8xC51 expects the LSB first. Therefore, the data read into
the serial buffer needs to be rearranged before the correct data
word from the AD7719 is available in the accumulator.
Figure 13. AD7719-to-8XC51 Interface
8xC51
P3.0
P3.1
DV
DD
10k
DV
DD
DOUT
RESET
DIN
SCLK
CS
AD7719
AD7719