Iron - In this issue I will continue to analyze the operation of the LSI DN-01.

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║ Iron.              ║
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(C) Klim Gromov

    Hello dear readers.  In this issue I will continue
analysis of the operation of LSI DN-01.

 "GENERATOR" mode.
 The generator produces harmonic signals with a frequency
496.5 or 420.1 Hz (rounded to 500 and 425 Hz, respectively).
The generator operation is controlled by signals D0 and D1
(when a recording signal is applied to the /WR input). The frequency of the generator is selected
uninterrupted signal at D1="1"F=425 Hz, and at D1="0"5OOHz. Turn on
Generator value (appearance of output signal at GEN pin)
carried out by setting D0="1".  Generator output
has a constant bias relative to the GND pin U=2.5 V (with
supply voltage 5 V) and alternating component with amplitude
value U=1.5 +-0.2 V for a frequency of 500 Hz and U=0.35 +-0.1 V for
frequency 425 Hz. In passive generator mode (D0="0") at the output
GEN forces digital ground potential
(GND), which ensures reliable locking of the bipolar transistor
tora.

 AGC node.
 In accordance with the standard, the signal level in telephone
communication lines can change, which requires the use of a circuit
AGC at the input of the microcircuit. The input node contains an open op-amp
the actual AGC unit (AGC) and the regulating element, made on
MOSFET transistor.

 Caller ID mode.
 In the "Caller ID" mode, the microcircuit decodes the signals transmitted
Caller ID PBX equipment into the communication line. The Caller ID signal represents the co-
sequence of ten two-frequency bursts, long
with a duration of 40 ms each. Harmonic signals have the following
frequencies: F0=700 Hz, F1=900 Hz, F2=1100 Hz, F4=1300 Hz, F7=1500
Hz and F11=1700 Hz. Tolerance for the installation accuracy of each frequency
is +-15 Hz. Filter bandwidths (relative to their
mid frequencies) are 30 Hz with adjacent channels attenuated
at less than 26 dB.
    After filtering and detection, two maxi-
small in signal amplitude Umax1 AND Umax2 (out of six) and transmitted
are input to the decoder that determines the NK itself. (here and
hereinafter NK-number combination).
    With this method of determining the code, the decoder (due to the presence
amount of noise in the channel) will always produce some kind of NC, even in
no input signal. To assess the reliability of information
On the NK there is a unit for measuring levels Umax1 andUmax2. BIS
compares the amplitude Umax1 with Umax/4 (Umaxmaximum
each signal at the AGC output), and Umax2 with Umax/10. As a result -
there the comparison flags FL2 AND FLЗ are set. Their conditions are
start:
 ┌─────┬─────┬─────┬─────┐
   │ FLЗ │ FL2 │ FL1 │ FLO │
   └──┬──┴──┬──┴──┬──┴──┬──┘
      │ │ │ │
      │ │ │ └────number reading flag
      │ │ │ combinations (NC)
      │ │ │ 0- there are changes
      │ │ │ 1- no changes
      │ │ │
      │ │ └──────────immutability flag
      │ │ combination numbers (NC)
      │ │ 0 - there are changes
      │ │ 1-normal level
      │ │
      │ └────────────────second level flag
      │ frequency signal
      │ 0 - not normal level
      │ 1-normal level
      │
      └──────────────────────level one flag
                             frequency signal
                           0-not normal level
                           1-normal level

      Confidence assessment table
   ┌───────────┬──────── ─────────────────────┐
   │CONDITION │ │
   │ FLAGS │ Degree of confidence │
   ├─────┬─────┤ ││ FLЗ │ FL2 │ │
   ├─────┼─────┼──────── ─────────────────────┤
   │ 0 │ 0 │ NO OUTPUT SIGNAL │
   ├─────┼─────┼──────── ─────────────────────┤
   │ 0 │ 1 │ CODE IS DOUBT │
   ├─────┼─────┼──────── ─────────────────────┤
   │ 1 │ 0 │ CODE IS NOT VALID │
   ├─────┼─────┼──────── ─────────────────────┤
   │ 1 │ 1 │ RELIABLE CODE │
   └─────┴─────┴──────── ─────────────────────┘
 Information at the output of the decoder is updated with frequency
32.768 kHz (clock frequency). For a more complete assessment of the reliability
The strength of the received information is indicated by the flag FL1 rising
only under the condition that the code at the output of the decoder remains unchanged in the current
time T (code change detector). To obtain the required
delay time for raising flag FL1 is necessary between outputs
You can connect CCD and GND to an external ceramic capacitor, and
between the CCD and +S terminals there is a resistor with a resistance of at least 1 kOhm.
In this case, the delay value T is determined as: T=0.9*R*C

 "LINE" mode.
 In the "LINE" mode, the ANI bandpass filters are disabled, and instead
them, an auxiliary
Low-pass filter with cutoff frequency F=6OOHz. The controller, reading the flags FLZ and
FL2, can get level informationand time parameters
signal coming from the line and make decisions based on this
information about the presence or absence of PBX signals. Selecting the "Caller ID" mode
or "LINE" is produced by setting bit D2 to "0" or "1" corresponding
respectively (when a recording signal is applied to the /WR input).

 "STANDBY" mode
 The current consumption of the microcircuit varies depending on the settings
new operating mode.  In the "Caller ID" + "GENERATOR" mode (D0="1",
D2="0") the microcircuit consumes maximum current. In "LINES" mode
(D2="1") Caller ID filters and the generator are de-energized and only work
AGC nodes, low-pass filter (600 Hz) and signal level measurement circuit. For
de-energizing of all IC nodes, it is necessary to send a write signal to
input /WR and set bit D3="1". In this case, the digital part of the circuit
continues to work.



    Finally, I want to say that we review the work of this mikruhi
we are finishing, but if anyone is seriously interested in her work, then
applications are accepted for the publication of detailed technical specifications
ristik DN-01.
    In the next issues of PROTON it is planned to analyze others, also
no less “tasty” microcircuits for telephony.
    Thanks for your attention, bye.
 Klim Gromov (Zxnet@095/366)
                                Recall to Kreator BBS- 366-6569