MagTek TRIPLE TRACK Delta ASIC - Manual (Page 12)

Triple Track ASIC
8
Taux (Auxiliary) = 0 s to 3.1 s
Time from the last detected signal peak of any track to the subsequent falling edge of DATA. Not a
concern for typical ISO data applications. Used only with custom data formats that allow 13 consecutive
zeroes as a valid sequence in the actual data portion of the card. When utilized, this edge indicates to the
controller that all ASIC buffers are completely full or a card swipe timeout has expired. The ZEROES
FLAG condition, if it occurs, must be cleared with a low pulse to STROBE to unmask this falling edge of
DATA indicating Taux has expired and BUFFER-READY.
Tsd (STROBE to DATA) = 170 ns maximum
Time from falling edge of STROBE until DATA is valid.
Tsc (STROBE to CLEAR) = 25ms maximum after any “card-in-progress” ends
Time from the 14,610
th
rising edge of STROBE, issued to reset the ASIC, until DATA assumes the idle
state and the unit is re-armed, ready to read. If there is a card swipe in progress when this STROBE is
issued, this Tsc time might not commence until the “card-in-progress” has ended as determined by the
ASIC. Tsc is also the time period immediately following a Watchdog timeout. In both cases, the ASIC is
performing a reset during this time and holding DATA low.
Twd (Watchdog) = 262 ms to 630 ms
Normally, the time from the falling edge of a STROBE pulse until the expiration of the “watchdog” or
reset timer. If this “watchdog” timer is allowed to expire, the ASIC’s buffer will normally be reset. If this
reset is allowed to happen, then DATA will be taken high to the “Buffer-Not-Ready” state after the time
“Tsc”. To prevent the “watchdog” timer from expiring, a STROBE falling edge must be issued prior to
the time “Twd” to restart the “watchdog” timer. The “watchdog” timer normally only starts running at the
falling edge of a STROBE pulse; however, there are two exceptions where the falling edge of DATA is
the starting point for the “watchdog” timer. These two exceptions occur at the beginning of the Shift-out
sequence, and are listed below:
1) The first run of the “watchdog” timer following a card swipe does not start at the falling edge of a
STROBE pulse, but instead starts at the first falling edge of DATA subsequent to a card swipe.
The latter of the falling edge of CLEAR-STROBE (1st STROBE) or the falling edge of DATA
indicating the AUXILIARY FLAG restarts the watchdog timer in this particular case. More time
than “Twd” is allowed from the initial falling edge of DATA until the first falling edge of
STROBE must be given. The point in time where the first falling edge of STROBE must be
given will be a maximum of 3.1 seconds from the beginning (wake-up) of the card swipe.
2) The second run of the “watchdog” timer following a card swipe does not necessarily begin at the
falling edge of the first STROBE pulse. The second run of the “watchdog” timer begins at the
falling edge of DATA indicating the AUXILIARY FLAG, unless the AUXILIARY FLAG was
masked by delay of the CLEAR-STROBE. In this case the falling edge of DATA indicating the
AUXILIARY FLAG is never seen, and the watchdog does begin on the falling edge of the delayed
CLEAR-STROBE. The falling edge of STOP-STROBE (2nd STROBE) restarts the
“watchdog” timer.
NOTE: THERE WILL BE NO WATCHDOG IN FUTURE REVISIONS OF THE ASIC.
Trdy (Ready) = 40 ms maximum (not shown)
Initialization time required after VDD becomes valid. Note that the state of DATA may be indeterminate
during this time and, therefore, an appropriate delay should be considered after applying power.