Z02205
ZiLOG
Modem Controller
PS001000-MOD0599 23
The following blacklisting parameters can be controlled:
Minimum delay in seconds between successive dial at-
tempts
Number of successive dial attempts after which the fol-
lowing parameter applies
Minimum delay in seconds between successive dial at-
tempts after
Unsuccessful dial attempts
Maximum number of dial attempts permitted in a series
of dial attempts
Blacklisting period in minutes for each series of dial at-
tempts
DYNAMIC POWER MANAGEMENT
The Z02205 incorporates a low-power SLEEP mode. In this
mode, the clock is shut down (effectively stopping the part).
The Modem Controller software automatically puts the mo-
dem’s data pump into a power-saving
SLEEP mode when it
is not used and there is no connection. The Modem Con-
troller software also puts the Modem Controller to sleep
when possible. This power-saving feature reduces the
amount of current used by 8 mA.
This sleep feature operates transparently to the modem’s op-
eration, saving approximately 58 mA of power when both
the modem data pump and controller are put into sleep
mode.
The modem controller goes to sleep under following con-
ditions:
Looking for an ’A’ (Auto Baud)
The ring line has been debounced
The RINGS register has been cleared
There are no incoming characters
There are no characters in the input queue
The Modem Controller is put to sleep until there is an in-
terrupt, such as:
A start bit from the terminal.
Telephone line ring detection from the telephone line in-
terface.
In
SLEEP mode, the modem controller turns off the main
timer interrupt and turns on the ring detect interrupt, leaves
the start bit interrupt running - then halts until an interrupt
occurs.
The Modem Controller cannot sleep if dial blacklisting has
been enabled in the country parameters and is being timed.
Nor can the Modem Controller sleep if
AT and D3 is set be-
cause a DTR On-to-Off transition can not wake it up
FUNCTIONAL DESCRIPTION
Clock. The Z02205 on-chip oscillator has a high-gain, par-
allel-resonant amplifier for connection to a crystal (XTAL1
is Input, XTAL2 is Output). The crystal should be
AT cut,
16 MHz max., with a series resistance (RS) of less than or
equal to 100 Ohms when counting from 1 MHz to 16 MHz.
Connect the crystal across
XTAL1 and XTAL2 using the ven-
dor’s recommended capacitor values from each pin directly
to the device
GROUND pin to reduce Ground noise injection
into the oscillator.
Note: For better noise suppression, the capacitors must be tied
directly to the device Ground pin (V
SS
).
