CS7654 Просмотр технического описания (PDF) - Cirrus Logic
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CS7654 Datasheet PDF : 62 Pages
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CS7654
EPROM are aborted and the NODEV status bit is
set in status register at address 01h at SA 0x34h.
The data within the EPROM is formatted in three-
byte packets that represent the destination address,
register address, and data. After reading a packet,
the CS7654 initiates an I2C bus cycle using the first
byte as the device station address, the second byte
as the device register address, and the third byte as
the data being written to the device. If an acknowl-
edge is received from the target device, the CS7654
will fetch the next 3 bytes from the EPROM and re-
peat the process. The only exception being the
gamma table whose entire 256 bytes is transferred
in one I2C write cycle. This process will continue
until the total number of packets read equals the
value in the EEPROM count register (registers 1Ah
and 1Bh at SA 0x34h), a HALT command is exe-
cuted, or NO ACKNOWLEDGE is received from
the target device.
While the CS7654 is downloading from the
EPROM, the INITACT bit (register 01h bit3 at SA
0x34h) is set in the status register of CS7654. All
attempts to write to CS7654 registers by an external
controller will be ignored during this time.
Controlling the Configuration Process
The simplest configuration would consist of an
EPROM with one configuration file. In this case,
the first commands in the EPROM should write the
total number of packets in the EEPROM. This data
is written to the EEPROM count high and low byte
registers (registers 1Ah and 1Bh at SA 0x34h).
Subsequent bytes would contain all the necessary
data to configure the camera. This data will be read
in a sequential fashion.
If, however, multiple configurations are desired,
the EEPROM may be programmed with multiple
sets of data, and the CS7654 programmed to select
one of 8 configurations. The appropriate configura-
tion is defined by the 3 GPIO[2:0] pins. The
CS7654 incorporates 3 commands to handle multi-
ple configurations: SKIP, JUMP, and HALT.
The SKIP command tells the CS7654 to skip to the
address within the EEPROM specified by the Con-
figuration Control registers (30h - 3Fh at SA
0x34h). The Configuration Control registers are
used in pairs to provide a 11-bit EEPROM address.
The Configuration Index Register determines
which two of the 8 pairs will be used.
The Configuration Index Register is loaded auto-
matically after reset by the CS7654. The CS7654
will read from the GPIO port. If the read cycle is
successful, the Configuration Index Register will
contain the state of the lower 3 bits of the parallel
I/O port. A set of shunts or DIP switches attached
to the I/O port provides a convenient way to select
up to 8 configurations. The SKIP command is exe-
cuted by writing a 1 to bit 1 of the EEPROM Con-
trol Register (42h at SA 0x34h).
The JUMP is similar to the SKIP command. The
user loads a jump address into the Jump Control
Registers (40h and 41h at SA 0x34h) and then ex-
ecutes the JUMP command by setting bit 2 of the
EEPROM Control Register (42h at SA 0x34h) to a
1. The jump command may be used to reduce the
amount of required EEPROM space by allowing
multiple configurations to share common data. For
example, three configurations may be necessary to
adjust for three different CCD timings, but they
may all share a common gamma table.
The HALT command is used to stop the execution
of the boot state machine. When all necessary data
has been read from the EEPROM, writing a 1 to bit
0 (HALT) of the EEPROM Control Register will
safely stop the boot process.
The total number of packets that may be stored in
the external EEPROM is 2k/3 or 682 3-byte com-
mands. Gamma table packets contain 259bytes.
A typical map of the EPROM table is shown in Fig-
ure 17. The only exception to this organization is
data for the CS7654 gamma table. The data for the
gamma table is organized as shown in Figure 18.
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