ACS ACR31 Swipe Card Reader - Manual (Page 6)

ACR31 – Reference Manual [email protected]
Version 1.00
www.acs.com.hk
Page 6 of 19
4.0. Hardware Design
4.1. Battery
ACR31 is using a CR2016 battery which has a capacity of 90 mAh.
4.2. Audio Channel
4.2.1. Communication Parameters
ACR31 is connected to a mobile device through Audio Channel.
Pin Signal Function
1 Left Transmit the data to ACR31
2 Right Reset signal to ACR31
3 GND GND
4 MIC Transmit the data to smart phone
Table 1: 3.5mm Audio Socket Wiring
4.3. Magnetic Stripe Card Interface
ACR31 can read any magnetic stripe card that conforms to ISO 7810/7811 standards. ISO 7810
specifies the physical characteristics of the card, while ISO 7811 specifies the recording technique
used in identification cards.
High-coercivity (HiCo) magnetic stripes are typically black in color and are encoded with a stronger
magnetic field (2750 Oersted). This makes HiCo cards more durable because the data encoded on
the stripes are less likely to be unintentionally erased when exposed to an outside magnetic field.
When swiped across the magnetic head, HiCo magnetic stripes can induce larger signal pulses and
are more easily being detected and decoded.
Low-coercivity (LoCo) magnetic stripes are generally brown in color and are encoded with lower
magnetic field intensity (300 Oersted). They will induce small signal pulses compared to HiCo cards
when swiped across the magnetic head. As a result, the S/N (signal-to-noise) ratio is relatively low
and they are more vulnerable to noise interference. A more sophisticated hardware support and signal
processing algorithm are needed to decode the signal correctly.
Since the magnetic fields of HiCo and LoCo cards are different, a magnetic stripe decoder IC with
automatic gain control can be used in the design to cater these two types of cards.