Figure 4. Pin Strap mode: Time Slot Assignment
CH0
Receive /Transmit
Time Slot
CHn
D7...................D0
FS0
D7..................D0
FSn
CHm
D7...................D0
FSm
STLC5046
TS23/31/61/127
register.
DX represent the transmit PCM interface. It re-
mains in high impedance state except during the
assigned time slots during which the PCM data
byte is shifted out on the rising edge of MCLK.
The four channels can be shifted out in any pos-
sible timeslot as defined by the DXA0 to DXA3
registers. If one codec is set in Power Down by
software programming the corresponding timeslot
is set in High Impedance. When linear coding
mode is selected by CONF register programming
the output channel will need two consecutive
timeslots (see register description).
DR represent the receive PCM interface. It re-
mains inactive except during the assigned time
slots during wich the PCM data byte is shifted in
on the falling edge of MCLK. The four channels
are shifted in any possible timeslot as defined by
the DRA0 to DRA3 registers.
Pin Strap Mode
When pinstrap mode is selected, dedicated
Frame Sync. FS3..0 are provided on dual func-
tion pins:
MCU
Pin-strap
Pin
FS
FS0
12
IO4
FS1
17
IO5
FS2
18
IO6
FS3
48
The PCMSH register cannot be accessed, there-
fore the beginning of the transmit and receive
frame is identified by the rising edge of the FSn
signal.
Each channel has its dedicated Frame Sync. sig-
nal FSn. Short or Long frame timing is automat-
ically selected; depending on the FS signal ap-
plied to FS0 input. The assigned Time Slot
(Transmit and Receive) takes place in the 8
MCLK cycles following the falling edge of FSn in
case of Short Frame or the rising edge in case of
Long Frame. If one codec is set in Power Down
by proper pin strap configuration the correspond-
ing timeslot is not loaded and the VFRO output is
kept at steady AGND level.
Finally by means of the LOOPB register is possi-
ble to implement a digital or analog loopback on
any of the selected channels.
TSX represent the Transmit Time Slot (open
drain output, 3.2mA). Normally it is floating in
high impedance state except when a time slot is
active on the DX output. In this case TSX output
pulls low to enable the backplane line driver.
Should be strapped to VSS when not used.
Table 1. Control byte structure.
First Byte (Address)
7
6
5
4
3
2
1
0
R/W D/S A5 A4 A3 A2 A1 A0
D7 D6 D5 D4 D3 D2 D1 D0
R/W = 0: Write Register
R/W = 1: Read Register
D/S = 0: Single byte
D/S = 1: Two bytes
A5..A0: Register Address
CONTROL INTERFACE
STLC5046 has two control modes, a microproc-
essor control mode and a pin strap control mode.
The two modes are selected by M0 and M1 pins.
When M0 = low, M1 = high (MCU control mode)
the MCU port is activated; and the 41 registers of
the device can be programmed. When M0 = high,
M1 = low (Pin-strap mode) the microprocessor
control port is disabled and some of the digital
pins change their function allowing to perform a
very basic programming of the device.
9/27