
SSR-1U User’s Manual
Rev -, 27 Dec 2019
© 2019 Slerj, LLC
8
www.slerj.com
Figure 4. Auxiliary Connector (View looking into the face of the connector)
Table 2. Auxiliary Connector Pins
Pin
1
ID
Description
1
GND
Ground connection for use with channel 4
2
2
T4
Asynchronous serial transmitter output for channel 4
3
3
R4
Asynchronous serial receiver input for channel 4
4
4
UEN
Enables USB access to the microSD card (recording disabled)
5
GND
USB ground connection
6
D+
USB D+ connection
7
D-
USB D- connection
8
5
5V
USB 5V supply
1
See Section 7.1 Electrical for detailed electrical specifications.
2
3.3V CMOS output
3
5V tolerant, TTL compatible, 3.3V CMOS input. Internally pulled up to 3.3 VDC.
4
5V tolerant, TTL compatible, 3.3V CMOS input. Active polarity is configurable using the Interactive Shell.
5
The SSR-1U has onboard diodes to allow power from either the main or aux connector, and both can be applied
simultaneously without damage to the device. It is not necessary to supply 5V on pin 8 to access USB if power
is supplied at the main connector.
Wiring for a typical application is shown in Figure 5. The default SSR-1U configuration is
assumed. In the figure, channel 4 is connected to a PC serial port for shell access, allowing
configuration and file system operations via a terminal application on the PC. Typically, this
connection is made using a USB to TTL serial adapter cable. When the
Close to Record
switch
is closed, channels 1, 2, and 3 on the main connector record data from connected serial devices.
While the default for channel 4 is shell access, it is a general purpose channel and can also be
configured for recording.
In the default configuration, USB mass media access to the microSD card is enabled when the
UEN pin is high. In the diagram, UEN is tied to the 5V USB supply so that USB access is
enabled when the USB cable is connected to the device.