Data Sheet

AS3588A

Rev. 3.1

Page 5 of 15

July 1999

of two data bytes and one command byte. Byte one

and two contain information about the PCM output line

and the PCM output channel and act as address

pointer to the specific connection memory location.

The command instruction is only executed if AS3588A

is selected by CS1=CS2=0 and if the condition A1=S1

and A2=S2 is met. If the device is only selected by

CS1 and CS2. this command is not executed and DR

remains high. If the instruction code was found to be

invalid, DR is driven low until a valid instruction code is

supplied; the registers are not modified.

3) BYTE INSERTION INTO A PCM OUTPUT

CHANNEL / CHANNEL DISCONNECTION

This function inserts a single byte from the micropro-

cessor into a PCM output channel. The control infor-

mation from the microprocessor consists of four data

bytes and one command byte. Byte one and two

contain the message byte from the microprocessor

which is stored in a connection memory location. Byte

three and four contain information about the PCM

output line and the PCM output channel and act as

address to the specific connection memory location

where the message byte that is contained in byte1 and

byte 2 is stored. If AS3588A is selected by CS1, CS2

and if the condition A1=S1 and A2=S2 is met, the

command instruction is executed as defined. If the

device is selected by CS1 and CS2 only this command

will perform a disconnect function on the specific

output channel. If the instruction code was found to be

invalid, DR is driven low until a valid instruction code is

supplied; the registers are not modified.

4) PCM OUTPUT CHANNEL EXTRACTION

This function extracts a specific output channel and

transfers it to the microprocessor bus. PCM input

channels can be extracted by connecting the channels

to output channels with instruction 1. The control infor-

mation from the microprocessor consists of two data

bytes and one command byte. Byte one and two

contain information about the PCM output line and the

PCM output channel. The extracted channel is stored

in the OR1 register. The command instruction is only

executed if AS3588A is selected by CS1=CS2=0 and

if the condition A1=S1 and A2=S2 is met. If the device

is only selected by CS1 and CS2. this command is not

executed and DR remains high.

If the instruction code was found to be invalid, DR is

driven low until a valid instruction code is supplied; the

registers are not modified.

5) TRANSFER OF A CONNECTION MEMORY

LOCATION

This function allows the access of the contents of a

connection memory location associated to a specific

PCM output channel and transfers it to the micropro-

cessor bus. The control information from the micropro-

cesor consists of two data bytes and one command

byte. Byte one and two contain information about the

PCM output line and the PCM output channel. The

connection memory bits C7 to C0 are stored in register

OR1, C8 is stored in register OR2. If C8=0 the

remaining eight bits contain information about the con-

nected PCM input channel. If C8=1, the remaining bits

can be all log. "1" if the output channel is not con-

nected to an input channel and if it was not modified

by the microprocessor. If C8=1 but the remaining bits

are not all set to log. "1" they contain a message byte

from an active output channel which was loaded by the

byte insertion instruction 3. DR goes low for two clock

cycles in that case. The command instruction is exe-

cuted if AS3588A is selected by CS1=CS2=0. If the in-

struction code was found to be invalid, DR is driven

low until a valid instruction code is supplied; the regis-

ters are not modified.

6) TRANSFER OF 0 CHANNEL PCM DATA FROM

SELECTED PCM INPUTS

This function is used to extract the contents of channel

0 of the PCM inputs which do not contain "01" in the

two most significant bits. The control information from

the microprocessor consists of two data bytes and one

command byte. Byte one and two contain information

about the PCM input selection mask byte. The

contents of channel 0 are available from the OR1

register from which the microprocessor can transfer

them by successive reads from the same register. To

enable instruction 6 it is necessary to read register

OR2. This is because instruction 6, used between

other short instructions of type 1 to 5 , must have a

lower priority and can be enabled only after the short

instructions have been completed. Instruction 6 nor-

mally has a long process and a special flow: First a

not-all-zero mask field is stored in the "expected

messages" register and in another "background" reg-

ister. A logic "1" means an input bus enabling condi-

tion, a log. "0" means an input bus disabling condition.

This operation starts the second phase of instruction 6

which is called "channel 0 extraction" and is repeated

at the beginning of any new time frame. At the

beginning of the time frame a new copy of activated

channels

to

be

extracted

is

made

from

the

"background register"' and put in the "expected mes-

sages'' register. In addition the latter register is modi-

fied to indicate the exact number of messages that

have arrived. The term messages covers any input 0

channel data with starting sequence different from

"01". Using this signature the number of expected

messages can be reduced to correspond to the

number of effective messages. If and only if the

residual number is different from zero will the device

start the extraction protocol at the end of the current

routine. The procedure is as follows:

The DR output is pulsed low for two clock cycles as in-

terrupt request to the microprocessor and OR2 is

loaded with the total number of active channels to be

extracted. The transfer of OR2 content to the micro-

processor continues the extraction which consists of

repeated steps of OR1 and OR2 loading indicating re-

spectively the message and the incoming bus number.