mh1020 Music Semiconductors, Inc., mh1020 Datasheet - Page 18

• Manufacturer Part Number: mh1020
• Description: Hla Packaged Asynchronous Data Recognition And Recall Processor
• Manufacturer: Music Semiconductors, Inc.

initialization, all devices are empty, thus the top device in
the string responds to a TCO PA instruction, and loads its
PA register. A Set Full Flag (SFF) instruction advances to
the next device in the string and is active only for the
device with /FI LOW and /FF HIGH. The SFF instruction
changes the first device’s /FF to LOW, although the device
really is empty, which allows the next device in the string
to respond to the TCO PA instruction and load its PA
register. The initialization proceeds through the chain in a
similar manner filling all the PA registers in turn. Each
device must have a unique Page Address value stored in
its PA register, or contention results. After all the PA
registers are filled, the entire string is reset through the
Control register, which does not change the values stored
in the individual PA registers. After the reset, the Device
Select registers usually are set to FFFFH to enable
operation in Case 1 of Table 4 on page 11. The Control
registers and the Segment Control registers are then set to
their normal operating values for the application.
Table 5: Initialization Routine Example
Notes:
1.
2.
3.
4.
Cycle Type
Command read
Command write
Command write
Command write
Command write
Command write
Command write
Command write
Command write
Command write
Command write
Command write
Command write
Command write
Command write
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.
This instruction may be omitted for a single MH application.
The last SFF causes 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.
A typical MH control environment: Enable match flag; Enable full flag; 48 CAM bits, 16 RAM bits; Disable comparison masking; and Enable
address increment. See Table on page 24 for Control Register bit assignments
SPS M@HM
on DQ Bus
Op-Code
TCO DS
TCO SC
TCO CT
TCO PA
TCO CT
TCO CT
FFFFH
0000H
nnnnH
0000H
8040H
3808H
SFF
/E
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
Control Bus
/CM
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
/W
H
L
L
L
L
L
L
L
L
L
L
L
L
L
L
/EC
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Comments
Clear power-up anomalies
Target Device Select register to disable local device selection.
Disable Device Select feature.
Target Control register for reset.
Causes Reset.
Target Page Address register to set page for cascaded operation.
Page Address value.
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.
Target Control register for initial values.
Control register value.
Target Segment Count Control register
Set both Segment counters to write to Segment 1, 2, and 3, and
read from Segment 0.
Set Data reads from Segment 0 of the Highest-Priority match
18
Vertically Cascaded System Initialization
Table 5 shows an example of code that initializes a
daisy-chained string of MH 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 MH devices are set for a
typical application. Each Page Address register must
contain a unique value (not FFFFH) to prevent bus
contention.
For typical daisy chain operation, data is loaded into the
Comparand registers of all the devices in a string
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 Table 4 on page 11 for
preconditions for reading and writing. Initialization for a
single MH 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.
Notes
Rev. 1
2,3
1
2
2
1
1
4
4
4