www.ti.com ................................................................................................................................................. SBOS438C – AUGUST 2008 – REVISED AUGUST 2009
Communication may be terminated by sending a
5. Send a STOP condition on the bus.
premature STOP or START condition on the bus, or
The BUF08821 acknowledges each data byte. If the
by not sending the acknowledge bit. The reading of
master terminates communication early by sending a
registers
DieID,
DieRev,
and
MaxBank
is
not
STOP or START condition on the bus, the specified
supported in this mode of operation (they must be
nonvolatile
register
is
not
updated.
Writing
a
read using the single register read method).
nonvolatile register also updates the DAC/VCOM
The register pointer increments directly from 000111
register and output voltage.
through 010010 to allow all eight gamma channels
The DAC/VCOM register and DAC/VCOM output voltage
plus the VCOM channel to be updated in one
are updated immediately, while the programming of
transaction.
the nonvolatile memory takes up to 250
μs. Once a
nonvolatile register write command has been issued,
Write: Nonvolatile Memory for the DAC Register
no communication with the BUF08821 should take
The BUF08821 is able to write to the nonvolatile
place for at least 250
μs. Writing or reading over the
memory
of
a
single
DAC/VCOM
in
a
single
serial interface while the nonvolatile memory is being
communication
transaction.
In
contrast
to
the
written jeopardizes the integrity of the data being
BUF20820, writing to multiple nonvolatile memory
stored.
words in a single transaction is not supported. Valid
DAC/VCOM pointer addresses begin with 000000
Read: Nonvolatile Memory for the DAC Register
(which corresponds to OUT1) through 000111 (which
To read the data present in nonvolatile register for a
corresponds to OUT8). Address 010010 is for VCOM.
particular DAC/VCOM channel, the master must first
When programming the nonvolatile memory, the
issue a general acquire command, or a single acquire
analog supply voltage must be between 9V and 20V.
command with the appropriate DAC/VCOM channel
Write commands are performed by setting the
chosen. This action updates both the DAC/VCOM
read/write bit low.
register(s) and DAC/VCOM output voltage(s). The
master
may
then
read
from
the
appropriate
To write to a single nonvolatile register:
DAC/VCOM register as described earlier.
1. Send a START condition on the bus.
Table 4. DAC Register Pointer Addresses
2. Send the device address and read/write bit =
LOW. The BUF08821 acknowledges this byte.
DAC REGISTER
POINTER ADDRESS
The
BUF08821
acknowledges,
stores,
and
OUT1
000000
returns data only from these addresses:
OUT2
000001
–
000000 through 000111
OUT3
000010
–
010010
OUT4
000011
See Table 4 for DAC/VCOM addresses. OUT5
000100
3. Send a DAC/VCOM pointer address byte. Set bit
OUT6
000101
D7 = 0 and D6 = 0. Bits D5–D0 are the
OUT7
000110
DAC/VCOM address.
OUT8
000111
4. Send two bytes of data for the nonvolatile register
of the specified DAC/VCOM. Begin by sending the
VCOM
010010
most significant byte first (bits D15–D8, of which
OTHER REGISTER
POINTER ADDRESS
only bits D9 and D8 are data bits, and bits
Die_Rev
111100
D15–D14 must be 01), followed by the least
Die_ID
111101
significant byte (bits D7–D0). The register is
MaxBank
111111
updated after receiving the second byte.
Copyright 2008–2009, Texas Instruments Incorporated
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