C H A P T E R 3 - S E R I A L I N T E R F A C E
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U S B - M D R 2 9 1 A
Universal Serial Bus (USB) is a connectivity specification developed by Intel and other technology industry
leaders. USB provides ease of use, expandability, and speed for the end user.
The USB bus supplies 5V DC regulated power (maximum 500mA) through each port on pins 1 and 4. Low-
power devices that might normally require a separate AC adapter can therefore be powered via the USB
cable, eliminating the need for associated AC adaptors. The MDR291A draws all of its power directly from
the USB bus and requires no external power supply.
U S B D E V I C E T Y P E S
There are two types of USB devices; Masters & Slaves. A USB Master device is essentially a host device
(i.e. PC) that supplies the USB drivers. A USB Slave device (peripheral devices such as a keyboard, mouse,
etc.) gets connected to a USB Master device and uses the USB driver supplied by the Host.
When a USB Slave device gets connected to the Host (i.e. PC), the Host prompts the device for the
appropriate USB driver. Once the driver has been located, the Host loads and retains it for all subsequent
connections of the Slave device. Note: The MDR291A is a USB Slave device (peripheral) and cannot be
connected to another USB Slave device.
U S B D R I V E R
The MDR291A is a stand-alone RF module that interfaces to a USB port on the Host device. It uses a
Virtual COM Port driver that causes the device to appear as an additional COM Port on the PC. Application
software can then access the USB device in the same manner as it would access a standard COM Port.
The MDR291A is a plug-and-play device that will automatically be detected by the PC upon connection.
Once detected, the PC starts the Add New Hardware wizard and installs the USB driver.
T A B L E 5 : M D R 2 9 1 A U S B T Y P E B P I N O U T
T E R M I N A L
B L O C K P I N
S I G N A L N A M E
D E S C R I P T I O N
C A B L E
C O L O R
1
V
BUS
4.75 - 5.25V @ 500mA
Red
2
D-
Transmit/Receive Data
White
3
D+
Transmit/Receive Data
Green
4
GND
Ground
Black
1
2
4
3
The Black Box USB Driver is installed automatically with the OEM Configuration Utility. It
can also be installed manually using the procedure below:
1
Connect the MDR291A device to the PC using a USB cable
2
Insert the Black Box Tools & Literature Disk into the CD drive.
3
Select Install from a specific location and then press the Next button.
4
Select Search for the best driver option.
5
Check the Search removable media (CD-ROM) box and then press Next.
6
If a Windows logo testing dialog appears, select Continue anyway.
7
Select Finish and reboot if prompted.
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