Philips Semiconductors
Preliminary specification
Economy audio CODEC
L3 interface
The UDA1345TS has a microcontroller input mode. In the
microcontroller mode, all of the digital sound processing
features and the system controlling features can be
controlled by the microcontroller. The controllable features
are:
•
System clock frequency
•
Data input format
•
Power control
•
DC filtering
•
De-emphasis
•
Volume
•
Mute.
The exchange of data and control information between the
microcontroller and the UDA1345TS is accomplished
through a serial hardware interface comprising the
following pins:
•
L3DATA: microcontroller interface data line
•
L3MODE: microcontroller interface mode line
•
L3CLOCK: microcontroller interface clock line.
Information transfer via the microcontroller bus is LSB first,
and is organized in accordance with the so called ‘L3’
format, in which two different modes of operation can be
distinguished; address mode and data transfer mode
(see Figs 4 and 5).
The address mode is required to select a device
communicating via the L3-bus and to define the
destination register set for the data transfer mode. Data
transfer for the UDA1345TS can only be in one direction:
for the UDA1345TS, data can only be written to the device.
Important:
since the UDA1345TS does not have a
Power-up reset circuit, after power up the L3 interface
registers MUST be initialized.
A
DDRESS MODE
The address mode is used to select a device for
subsequent data transfer and to define the destination
register set (DATA or STATUS). The address mode is
characterized by L3MODE being LOW and a burst of
8 pulses on L3CLOCK, accompanied by 8 data bits.
The fundamental timing is shown in Fig.4. Data
bits 0 and 1 indicate the type of subsequent data transfer
as given in Table 12.
Table 12
Selection of data transfer
BIT 1
0
0
1
1
BIT 0
0
1
0
1
UDA1345TS
TRANSFER
DATA (volume, de-emphasis, mute,
and power control)
not used
STATUS (system clock frequency, data
input format and DC filter)
not used
Data bits 7 to 2 represent a 6-bit device address, with bit 7
being the MSB and bit 2 the LSB. The address of the
UDA1345TS is 000101 (bit 7 to bit 2). In the event that the
UDA1345TS receives a different address, it will deselect
its microcontroller interface logic.
D
ATA TRANSFER MODE
The selection preformed in the address mode remains
active during subsequent data transfers, until the
UDA1345TS receives a new address command.
The fundamental timing of data transfers is essentially the
same as in the address mode, shown in Fig.4. The
maximum input clock and data rate is 128f
s
. All transfers
are byte wise, i.e. they are based on groups of 8 bits. Data
will be stored in the UDA1345TS after the eighth bit of a
byte has been received. A multibyte transfer is illustrated
in Fig.6.
Programming the sound processing and other features
The feature values are stored in independent registers.
The first selection of the registers is achieved by the choice
of data type that is transferred, being DATA or STATUS.
This is performed in the address mode, bit 1 and bit 0
(see Table 12). The second selection is performed by the
2 MSBs of the data byte (bit 7 and bit 6). The other bits in
the data byte (bit 5 to bit 0) are the values that are placed
in the selected registers.
When the data transfer of type DATA is selected, the
features Volume, De-emphasis, Mute and Power control
can be controlled. When the data transfer of type STATUS
is selected, the features system clock frequency, data
input format and DC filter can be controlled.
2000 Apr 18
12
PHILIPS [ NXP SEMICONDUCTORS ]
