Access OCR640 Quick start guide

OCR640 –Operational Description
OCR640 is an USB connected passport reader which has a Camera Imager and a RFID contactless reader.
The camera is used to capture images by the host application, which then decodes the passport MRZ
data. The MRZ data is then sent to the RFID reader to authenticate with the RFID chip in the passport to
read the data. The following figure shows the hardware architecture of OCR640.
Fig 1: OCR640 Hardware Architecture

The USB Hub #1 is mainly used as a placeholder for future expansions. The USB hub #2 is used to
connect the camera and the RFID to the USB upstream bus. The USB camera imager controls both the
sounder and the lighting board through SPI and I2C respectively. The Lighting board is quite flexible to
provide UV or IR or white illumination as requested by the imager.
The RFID contactless reader drives two independent antennas. There is one antenna around the glass
window. This antenna will be referred as antenna #1 in this document. The other antenna is behind the
front face of the product. This antenna will be referred as antenna #2 in this document. Typically, both
these antennas will be scanning for RFID passports –one at a time.
High Speed USB Hub (#1 & #2):
Device classification
2 port USB High speed hub
Operating Voltage / Current
3.3V / 150mA
Digital/Analog
Digital circuitry
Crystal Frequency
24 MHz
PLL Multiplier
x20 (480 MHz internal frequency)
Data transfer rate
480Mbps
Intentional Radiation
No
Software requirements
USB host should have generic USB hub driver. All windows machine
supports this USB hub class and it should start up right away. There are
not application software requirements.
Operational Description:
High speed USB hub #1:
This high speed USB hub is used for future extension of the product.
High speed USB hub #2:
This High speed USB hub provides USB connectivity to the RFID and the camera. It provides two USB
downstream ports. One of the downstream ports is connected to a RFID full speed device and the other
is connected to a 1.3 Mega pixel imager.
Camera Imager:
Device classification
USB 2.0 High speed camera
Operating Voltage / Current
5V / 150mA
Digital/Analog
Digital circuitry
Crystal Frequency
24 MHz
PLL Multiplier
x20 (480 MHz internal frequency)
Data transfer rate
480Mbps
Intentional Radiation
No
Image resolution
2048 x 1536 (3.1 Mega pixel)
Software requirements
USB host should have Access IS camera drivers installed. The camera
starts-up only if camera application software (like Amcap or IScap) is

running. The camera shuts down when then application software is
closed.
Operational Description:
The camera imager is a USB 2.0 high speed camera capable of streaming images at 3.1 Mega pixel
resolutions. The data from the camera reaches the USB host through the USB high speed hub. It should
be noted that the camera is in shutdown state when there is no application software running. For
normal operation camera application software like Amcap or IScap should be running.
It should be noted that the lighting circuit is controlled by the imager. The right illumination could be
selected appropriately by the imager circuit and this kind of arrangement helps the USB host software to
control the illumination.
The following diagram shows the internal blocks of the camera imager along with the lighting circuit.
Fig 2: Camera imager internal block diagram

Lighting board:
Device classification
Boost regulator for lighting application
Operating Voltage / Current
5V / 250mA
Digital/Analog
Analog circuitry
Switching Frequency
~500KHz
LED drive Voltage / Current
~25V / 20mA (Drives a string of IR, UV, White LEDs)
Intentional Radiation
No
Software requirements
None. Starts up as soon as power is applied
Operational Description:
The lighting board drives a set of IR, UV and white LEDs. The circuit is controlled by the imager circuit
through I2C interface. The choice of IR/UV/White illumination is done by the host application and is
handed down to the lighting board through the I2C interface. The lighting board has a step up DC-DC
converter and current controlled LED drivers to accomplish the intended purpose.
Sounder:
Device classification
Audible tone generator
Operating Voltage / Current
3.3V / 20mA
Digital/Analog
Digital circuitry
Operating Frequency
8 MHz
Intentional Radiation
No
Software requirements
None. Camera imager digital circuit controls the tone generator. The
communication is through SPI interface operating at 100KHz.
Operational Description:
Sounder block is basically a small microcontroller that generates tones. The sounder controller receives
commands from the camera digital circuit on which tone it has to play. With this kind of arrangement,
the USB host software can access the sounder through the camera digital circuit.

RFID Contactless Reader
RFID contactless reader contains both digital and analog section. Information on these two sections are
provided below.
RFID Contactless Reader –Digital Section
Device classification
USB full speed device
Operating Voltage / Current
5V / 50mA
Digital/Analog
Digital circuitry
Crystal Frequency
8 MHz
PLL Multiplier
x6 (48 Mhz internal frequency)
Data transfer rate
12Mbps
Intentional Radiation
No
Software requirements
Microsoft CCID smartcard driver is required. Only if the driver is loaded
in the host machine the digital section will enable the RFID analog
section. There are no application software requirements to get the RFID
active. However, to reader RFID passport application software (like
Golden reader tool) is required.
RFID Contactless Reader –Analog Section
Device classification
RFID transceiver
Operating Voltage / Current
5V / 150mA
RFID protocol
ISO14443 Type A and Type B
Digital/Analog
Analog circuitry
Crystal Frequency
13.56 MHz
PLL Multiplier
None
RF Data transfer rate
424 Kbps
Intentional Radiation
Yes
Carrier frequency
13.56 Mhz +/- 7 KHz
Sub Carrier frequency
847 KHz (max)
Number of Antenna
2
Output power
< 250 mW
RF field strength
6 A/m (RMS)
Software requirements
Refer the RFID contactless reader - digital section software requirements
Operational Description:
The RFID contactless reader is a proximity reader that operates on 13.56 Mhz carrier frequency. It
communicates to RFID passports using ISO14443 A/B protocols. The reader has two inbuilt antennas and
it keeps switching the carrier between the two antennas, polling for RFID passports. The following
diagram shows the internal blocks of the RFID reader.

Fig 3: RFID reader internal block diagram
Note that there are two identical channels for driving antenna #1 and antenna #2. The RFID digital
circuit controls both the antenna channels. The EMC filter provides the necessary attenuation to block
higher frequency harmonics from reaching the antenna. The matching network along with the balun
provides the required matching to a 50 Ohm antenna.
The RFID reader uses loop antenna to radiate RF energy. The antennas are tuned to 50 Ohm impedance
with a phase angle of +/- 10 degrees. The following diagram shows a simplified circuitry of the antenna.
Fig 4: RFID loop antenna circuit
The antenna board has two loop antennas tuned to operate at 13.56 MHz. Antenna #1 is around the
glass window and antenna #2 is below the front face of the product. Variable capacitors are used in
place of C1 and C2 so that the antenna could be tuned accurately during production. The following plots
show a typical antenna impedance plots for both antenna #1 and #2.

Fig 5: OCR640 Antenna #1 –Typical Impedance and Phase plot
Fig 6: OCR640 Antenna #2 –Typical Impedance and Phase plot
As said earlier, the RF energy is switched between the antennas one at a time, scanning for RFID
passports. The antenna switching and the polling sequence timing are shown in the following diagram.
Z = 50 Ohm (+/- 3 Ohm)
Ф = +/- 10 degree
Z = 50 Ohm (+/- 3 Ohm)
Ф = +/- 10 degree

Fig 7: RFID antenna switching and polling sequence
Once a passport is detected the RFID reader exchanges data with it and stays locked on to the RFID
passport. As long as the passport stays in the communicable range, the antenna switching/polling does
not happen.
It should be noted that the reader always does transceive operation. (i.e. Transmits command and
receives or expects reception of data from the RFID passport). Hence, it is NOT possible to have the
reader in transmit only or receive only mode.