LMC1992 NSC [National Semiconductor], LMC1992 Datasheet - Page 11

• Manufacturer Part Number: LMC1992
• Description: LMC1992 Digitally-Controlled Stereo Tone and Volume Circuit with Four-Channel Input-Selector
• Manufacturer: NSC [National Semiconductor]

ure 6 are examples of COPS
Applications Information
DATA TRANSFER EXAMPLE
The following routines based on the flowchart shown in Fig-
code that can be used to control the LMC1992 (see Nation-
al Semiconductor’s COPS Microcontrollers Databook for
more information) These routines arbitrarily select COPS
register 0 for I O purposes When these routines are en-
tered it is assumed that chip select is high SK (clock) is
low and SO (data) is low These routines exit with chip se-
lect high and SK and SO low Output port G0 is arbitrarily
chosen to send the chip select signal to the LMC1992
The 11 data bits needed to control the LMC1992 are as-
sumed to be in the 4-bit registers 13–15 with the 4 MSBs
in register 13 With this configuration there is an extra bit for
a data stream that is 12 bits long As previously mentioned
there can be any number of extra bits between the device
address and the function address
DATA TRANSFER ROUTINE 1
This general purpose routine handles all the overhead ex-
cept loading data into registers 13–15 It sends the data
according to the conditions discussed above The data will
be lost at the conclusion of the routine This routine con-
sumes only 17 ROM memory locations
OUT1
SEND
LBI
SC
OGI
LEI
LD
XAS
XIS
JP
RC
OGI
LEI
RET
0 13
14
8
SEND
15
0
POINT TO START OF DATA
WORD
SET C TO ENABLE SK CLOCK
SELECT EXTERNAL DEVICE G0
ENABLE SHIFT REGISTER
OUTPUT
DATA TRANSMISSION LOOP
TURN-ON CLOCK
DE-SELECT EXTERNAL
DEVICE
SET S0 TO 0
0
TM
microcontroller instruction
(Continued)
11
DATA TRANSFER ROUTINE 2
This routine performs the same function as routine 1 while
preserving the contents of the data registers This routine
takes only 21 ROM memory locations
OUT1
SEND1
SEND2
LBI
SC
OGI
LEI
JP
XAS
LD
XIS
JP
XAS
RC
CLRA
NOP
XAS
OGI
LEI
RET
0 13
14
8
SEND2
SEND1
15
0
GO
POINT TO START OF DATA
WORD
SET C TO ENABLE SK CLOCK
SELECT EXTERNAL DEVICE
ENABLE SHIFT REGISTER
OUTPUT
DATA TRANSMISSION LOOP
TURN-ON CLOCK
SEND LAST DATA
WAIT 4 CYCLES - DATA
GOING OUT
TURN SK CLOCK OFF
DE-SELECT DEVICE
SET S0 TO 0
0