MC34216A Datasheet, PDF (15/20 Pages) Motorola, Inc – PROGRAMMABLE TELEPHONE LINE INTERFACE CIRCUIT WITH LOUDSPEAKER AMPLIFIER

MC34216A
Programming Possibilities
The MC34216A can be programmed by a microcontroller
via a 2 wire bus. In this way, it is possible to program the dc
mask, DTMF tones, listening–in mode, loudspeaker volume,
etc.
The bus interface of the microcontroller with the
MC34216A consists of 2 wires: a data wire and a clock wire
connected to Pins D/HS and CLK respectively. Also, the
reset Pin RST of the MC34216A is connected to the
microcontroller. The MC34216A itself has a local oscillator
connected to Pin Osc.
The local oscillator needs a 500 kHz parallel mode
ceramic resonator, with approximately 75 pF capacitance,
connected to ground (for instance, the TOKO
FCRK500A–P35). The local oscillator is the reference for all
the internal timings of the MC34216A.
The 2 wire bus is based on the SCI standard. This
standard includes things such as de–bouncing and bus
monitoring in order to check that the data is sent over
correctly. The full bus specification is depicted in Figure 14.
The data is read in during the falling edge of the clock signal.
The clock has to be active only during the transfer of the data.
After the data is sent, the clock has to be kept low.
The D/HS pin is not only the input for the data but also the
output for the hookswitch information. When there is line
current flowing, this pin will be high, provided that the clock
line is low.
The reset Pin RST of the MC34216A is high for supply
voltages on VCC of 3.1 V and higher. It is the indication for the
microcontroller that programming of the device is possible.
When RST becomes high and D/HS is high as well, the
microcontroller can start programming the registers for the
speech mode. When information from the ringer indicates
that there is a ring signal present on the line, the
microcontroller can start programming the registers for
ringing mode.
The registers of the MC34216A are 8–bits wide. The
register bits are shown in Figure 15. The 8–bits can be split
up into 2 address bits and 6 data bits of the format
A1A0D5D4D3D2D1D0. Data is sent over starting with the
address bits (A1 and A0) and then the data bits, D5 through
D0.
During startup of the MC34216A, the registers are
internally reset in order to have a defined state. The contents
of the registers after the reset are also given in Figure 15. In
summary, it starts up with LV mask and handset mode with
the transducers muted.
Figure 14. Bus Specification
TI
Tclk
T(on)
Clk
D/HS
Clk
TDS
TDH
T1
D/HS
Symbol
Tclk
T(on)
TDS
TDH
TD
TI
T1
Vihc
Vilc
Vihd
Vild
Description
Clock Period
High Level Duration
Data Setup Time
Data Hold Time
Debounce Time
Data Reset Time to First Clock Rising Edge
Interval Between 2 Successive 8–Bit Words
High Input Level – Clock
Low Input Level – Clock
High Input Level – Data
Low Input Level – Data
Min
Max
Unit
125 1000
µs
66
–
µs
10
Ton
µs
20
900
µs
16
–
µs
40
–
µs
700
–
µs
0.7
5.0
Vdc
0.0
0.3
Vdc
1.7
5.0
Vdc
0.0
1.2
Vdc
MOTOROLA ANALOG IC DEVICE DATA
15