PPC-E4+ User Manual.doc
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Rev 1.4 © 2015 EMAC, Inc.
Table 7 (COM D Pinout) (HDR5)
#
Pin Description for 10-Pin
Header
Pin Description for DB9
Connector
1
NC
NC
2
NC
RxD
3
RxD
TxD
4
RTS
NC
5
TXD
GND
6
CTS
NC
7
NC
RTS
8
NC
CTS
9
GND
NC
10
NC
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2.5 USB Host Ports
The PPC-E4+ provides one USB 2.0, high speed host port (PortA) and one USB 2.0, high speed OTG port
(PortC). USB PortA and PortB can be accessed from HDR6. PortC can be accessed from the on-board USB
connector JK2. Note: PortB is not available when using the SoM-9G45 SoM as it only supports two USB ports, A
& C.
All of the USB ports are equipped with 500mA re-settable Polyfuses. If a USB Device tries to draw more than
500mA from the port, the fuse will open until the device is unplugged or its current requirement is reduced. There
is no software provision for shutting down power to the Ports or detecting when a port is drawing too much
current.
Note:
When sizing a power supply, make sure to allow for USB Device consumption. A device can potentially
draw 500mA, therefore these devices could use a total of up to 1 amp of power.
2.6
Audio Port
The PPC-E4+ provides optional Audio Line Out and Line In capability through a two 4-pin 1.25mm headers (CN4
& CN5). A special cable (included with the Audio Option) converts the signals present on the header to two
standard miniature audio jacks. The processor interfaces to the Audio CODEC through its I
2
S interface.
Command control of the CODEC is done using the processor’s SPI interface. The CODEC is the Cirrus CS4271,
which is a high performance 24-bit Stereo CODEC offering superior sound quality.
Both the input and output are line level. You will probably not be able to drive an unamplified speaker although
standard headphones will work. Likewise, an un-amplified microphone probably will not work as an input although
the line out of a CD player will work.
2.5
LCD Brightness Control
The PPC-E4+ offers LCD brightness control that can change the brightness of the LCD via software. The LCD
utilizes LED backlighting. The board provides the backlight with a constant current source of 20mA which results
in a voltage of approximately 30 volts. The processor provides a PWM (SoM Pin #85) that is used to drive the
LCD backlight. Changing the duty-cycle of the PWM directly affects the brightness of the LCD. In addition, the
backlight can be turned off by setting SoM Pin #114 low. This allows screensaver software to automatically turn
off the backlight when the unit is not being used and to automatically turn it back on when the touchscreen is
touched.
