Cirrus Logic CDB8130 - Manual (Page 3)

CDB8130
DS170DB5 3
1 CS8130 INFRARED TRANSCEIVER
The CDB8130 provides an example application of
the CS8130 infrared transceiver. This application
is similar to an IR pod system that is designed to
plug into any standard RS-232 port, like the COM
port on the back of an IBM
®
-compatible PC, to
provide an easy-to-use infrared interface.
Additionally, the board allows for easy interfacing
directly to the CS8130 through stake header J11 al-
lowing other applications to be easily realized.
Figure 1 shows the CS8130 and RS-232 level
translator connections.
A description of the CS8130 including register def-
initions, control pin assignments, and other useful
information can be found in the CS8130 data sheet.
1.1 Power Supply Circuitry and
Grounding
Figure 2 shows the power supply configuration of
the evaluation board. Power is supplied to the
board by two terminal blocks and a DC power jack,
J21, J22, and J23 (DCPWR). To operate the board
from a single power supply, stake jumper J20 must
be installed. In this configuration, power should be
supplied to the board through the VD+/DGND ter-
minal block (J21) or the DCPWR jack (J23).
A 3.3V regulator, U5, is supplied on the board. To
use this regulator, stake jumper J2 (USE REG)
should be installed. To bypass the regulator, J1
(NO REG) should be installed.
To isolate the power supply driving the CS8130
from the supply powering the rest of the circuitry,
remove J20, and feed the CS8130’s power supply
into the VA+/AGND terminal block (J22). The rest
of the circuit should be powered through either the
VD+/DGND terminal block (J21) or the DCPWR
jack (J23).
Using the on-board voltage regulator, the evalua-
tion board may be powered from any DC voltage
between +4V and +6.5V. If the voltage regulator is
bypassed, the acceptable operating voltage is be-
tween +2.7V and +5.5V (defined by the power sup-
ply requirements of the CS8130.)
The evaluation board is split into two ground
planes, an analog plane and a digital plane. The
CS8130 and IR components reside on the analog
plane, and the RS-232 level translator, reset circuit,
and status indicator circuitry lie over the digital
ground plane. The ground planes are connected in
exactly one place at jumper J31, located near the
power supply connections.
1.2 Reset Circuit
Figure 3 shows the power-up and user-activated re-
set circuit. As shipped from the factory, this circuit
is not used. The RESET signal is instead supplied
by the RS-232 interface signal RTS. This configu-
ration allows the CS8130 to be reset under software
control.
To derive the reset function from the power-
up/manual reset circuit instead, remove stake
jumper J9 (RTS) and install stake jumper J12 (RE-
SETSW). These jumpers are shown in Figure 1.
1.3 Optical Interface
The CDB8130 is shipped with Temic
®
and
Hewlett-Packard
®
IR components installed. The
receiver PIN diode is Temic model BPV 22 NF.
Transmit LED D5 is a Hewlett-Packard HSDL-
4220, and D6 is a Temic TSHA5502.
These components are not soldered in place. In-
stead, they are held by gold-plated pins. These pins
allow for any insertion and removal of other IR
components for performance and compatibility
evaluation.
The default configuration for the transmitter circuit
has one LED per output driver. One or both LEDs
can be active at the same time by programming the
appropriate register in the CS8130, allowing soft-
ware to control the transmitter output power.
Additionally, the transmit drivers on the CS8130
can be connected in parallel to share current. This