AD6642 Analog Devices, AD6642 Datasheet - Page 26

• Manufacturer Part Number: AD6642
• Description: Dual IF Receiver
• Manufacturer: Analog Devices

AD6642
MEMORY MAP
READING THE MEMORY MAP REGISTER TABLE
Each row in the memory map register table has eight bit loca-
tions (see Table 13). The memory map is roughly divided into
four sections: the chip configuration registers (Address 0x00
and Address 0x01); the channel index and transfer registers
(Address 0x05 and Address 0xFF); the ADC function registers,
including setup, control, and test (Address 0x08 to Address 0x25);
and the digital feature control registers (Address 0x3A to
Address 0x3E).
The memory map register table (see Table 13) provides the
default hexadecimal value for each hexadecimal address shown.
The column with the heading (MSB) Bit 7 is the start of the
default hexadecimal value given. Application Note AN-877,
Interfacing to High Speed ADCs via SPI, documents the functions
controlled by Register 0x00 to Register 0xFF. The remaining
registers, Register 0x3A to Register 0x3E, are documented in
the Memory Map Register Descriptions section.
Open Locations
All address and bit locations that are not included in Table 13 are
not currently supported for this device. Unused bits of a valid
address location should be written with 0s. Writing to these
locations is required only when part of an address location is
open (for example, Address 0x18). If the entire address location
is open (for example, Address 0x13), this address location
should not be written.
Default Values
After the AD6642 is reset, critical registers are loaded with
default values. The default values for the registers are given in
the memory map register table (see Table 13).
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Logic Levels
An explanation of logic level terminology follows:
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Transfer Register Map
Address 0x08 to Address 0x3E are shadowed. Writes to these
addresses do not affect part operation until a transfer command
is issued by writing 0x01 to Address 0xFF, setting the transfer
bit. This allows these registers to be updated internally and
simultaneously when the transfer bit is set. The transfer bit is
autoclearing.
Channel-Specific Registers
Some channel setup functions, such as the NSR control func-
tion, can be programmed differently for each channel. In these
cases, channel address locations are internally duplicated for
each channel. These registers and bits are designated in Table 13
as local. Local registers and bits can be accessed by setting the
appropriate channel bits in Register 0x05.
If multiple channel bits are set, the subsequent write affects the
registers of all selected channels. In a read cycle, only a single
channel should be selected to read one of the registers. If multiple
channels are selected during a SPI read cycle, the part returns
the value for Channel A only. Registers and bits designated as
global in Table 13 affect the entire part or the channel features
for which there are no independent per-channel settings. The
settings in Register 0x05 do not affect the global registers and bits.
“Bit is set” is synonymous with “bit is set to Logic 1” or
“writing Logic 1 for the bit. ”
“Clear a bit” is synonymous with “bit is set to Logic 0” or
“writing Logic 0 for the bit. ”