MU9C2480A/L
OPERATIONAL CHARACTERISTICS Continued
simultaneously by setting DS=FFFFH. Since reading is
prohibited when DS=FFFFH (except for the device with
a match), for a diagnostic operation you need to select a
specific device by setting DS=PA for the desired device
to be able to read from it. Refer to Tables 5a and 5b on
page 12 for preconditions for reading and writing.
Vertically Cascaded System Initialization
Table 6 shows an example of code that initializes a daisy-
chained string of LANCAM devices. The initialization
example shows how to set the Page Address registers of
each of the devices in the chain through the use of the
Set Full Flag instruction, and how the Control registers
and Segment counters of all the LANCAM devices are
set for a typical application. Each Page Address register
must contain a unique value (not FFFFH) to prevent bus
contention.
Initialization for a single LANCAM is similar. The Device
Select register in this case is usually set to equal the
Page Address register for normal operations. Also, the
dedicated /MA flag output can be used instead of /MF,
allowing /EC to be tied HIGH.
For typical daisy chain operation, data is loaded into the
Comparand registers of all the devices in a string
Notes
Control bus
Cycle type
Op-Code
Comments
on DQ Bus
/E /CM /W /EC
Command read
Command write
Command write
Commandwrite
Command write
Command write
Command write
Command write
Clear power-up anomalies.
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
L
L
L
L
L
L
L
TCO DS
FFFFH
TCO CT
0000H
TCO PA
nnnnH
SFF
Target Device Select Register to disable local device selction.
Disable Device Select feature.
Target Control register for reset.
Causes Reset.
1
2
Target Page Address register to set page for cascaded operation.
Page Address value.
2
H
H
Set Full flag; allows access to next device (repeat previous
two cycles plus this one for each device in chain.
Target Control register for reset of Full flags, but not Page address.
Causes Reset.
2,3
Command write
Commandwrite
Command write
Command write
Command write
Command write
TCO CT
0000H
1
1
4
4
L
L
L
L
L
L
L
L
L
L
L
L
H
H
H
H
L
L
L
L
L
L
TCO CT
8040H
Target Control register for initial values.
Control register value.
TCO SC
3808H
Target Segment Count Control register
H
H
Set both Segment Counters to write to Segment 1, 2 and 3, and
read from Segment 0.
4
Set Data Reads from Segment 0 of the Highest-Priority match.
Command write
H
SPS M@HM
L
L
L
Notes:
1. Toggling the /Reset pin generates the same effect as this reset of the Control register, but good programming
practice dictates a software reset for initialization to account for all possible prior conditions.
2. This instruction may be omitted for a single LANCAM application.
3. The last SFF will cause the /FF pin in the last chip in a daisy chain to go LOW. In a daisy chain, DS needs to be set equal to PA
to read out a particular chip prior to a match condition.
4. A typical LANCAM control environment: Enable match flag; Enable full flag; 48 CAM bits, 16 RAM bits; Disable comparison
masking; and Enable address increment. See Table 8 on page 21 for Control Register bit assignments.
Table 6: Example Initialization Routine
Rev. 1a
16
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