MagTek LOW POWER SHIFT-OUT - Manual (Page 9)

Low Power Shift-Out IntelliHead
3
SHIFT-OUT PROTOCOL
Refer to MagTek specification 99875337 for details of the Shift-Out Protocol. The Low Power
Shift-Out IntelliHead functions identically to the regular Shift-Out IntelliHead, except as noted
in this document. This document (99875349) takes precedence over 99875337.
The exact same Shift-Out protocol (New Mode) for the regular Shift-Out IntelliHead may also be used
for the Low Power Shift-Out IntelliHead. To take advantage of the low power feature, though, a
special protocol must be followed. This special protocol delays the reset sequence by 300 ms, so it can
be advantageous to use the regular Shift-Out protocol when a quick re-arm time is desired. This is
typically the case for insert or dip type readers. A quick reset is needed if it is desired to read on
withdrawal of the card. Note that this imposes no penalty on battery life, since after the card
withdrawal, the IntelliHead may be put back into the low power armed-to-read state with the special
protocol.
To put the unit in its special low power armed-to-read state, after STROBE is taken high entering the
OFF state as a part of the reset sequence, delay at least 300 ms, and then take STROBE from its high
state to a high-impedance state (high-Z). The unit is now in its special low power armed-to-read state,
although the Delta ASIC internal to the Low Power IntelliHead is in its OFF state.
When in the special low power armed-to-read state, the Low Power IntelliHead will only respond to
the track 2 signal for “wake-up”. Once “awakened”, tracks 1 and/or 3 will be read if encoded. Cards
that do not have track 2 encoded will not read reliably. They may read sometimes due to some DC
magnetization of the intended blank track 2 stripe causing a sufficiently large signal to trip the “wake-
up” circuit.
From the special low power armed-to-read state, STROBE will fall when a card is detected. STROBE
will remain low for at least 100ms
1
. The user’s micro-controller must actively drive STROBE low
(even though it is being driven low by the IntelliHead) within this 100ms window. STROBE should
be push-pull now until it is again set to high-Z at the end of the next special reset sequence. If the
100ms window is missed, indeterminate operation may result, and another reset should be performed.
From the falling edge of STROBE signaling the beginning of a card swipe, the MCU must hold
STROBE low and wait for DATA to fall, indicating the Card-Present (CP) condition. If there is no CP
within 30ms, a reset should be performed. If CP is seen within 30ms, then operation should proceed
as detailed in 9875337 for the remainder of the shift-out sequence.
The information below is needed for the firmware designer to assign the memory-tracks of the ASIC
(A, B, and C) to the physical magnetic head tracks (1, 2, and 3).
The on-chip memory tracks of the Low Power Shift-Out IntelliHead are permanently assigned to
particular tracks of the magnetic head via internal wires connecting the head coil wires to particular
inputs of the built-in ASIC. As it is oriented in Figure 3, tracks ‘A’, ‘B’, and ‘C’ of the internal ASIC
correspond to tracks ‘1’, ‘2’, and ‘3’ of the reader respectively. The IntelliHead may be mounted with
the opposite orientation if desired, but firmware must anticipate this re-mapping of ASIC memory
tracks to physical magnetic head tracks.
1 If compatibility with the future MagnePrint™ Low Power IntelliHead is desired, a 25 μs window should be respected
instead of a 100 ms window. MagnePrint is a security feature that can distinguish counterfeit cards from the original card.