LEA-6 / NEO-6 / MAX-6 - Hardware Integration Manual
UBX-14054794 Production Information Hardware description
Page 10 of 85
1.5 System functions
1.5.1 System monitoring
The u-blox-6 receiver modules provide system monitoring functions that allow the operation of the embedded
processor and associated peripherals to be supervised. These System Monitoring functions are output as part of
the UBX protocol, class ‘MON’.
Please refer to the u-blox 6 Receiver Description including Protocol Specification [4]. For more information on
UBX messages, serial interfaces for design analysis and individual system monitoring functions.
1.6 Interfaces
1.6.1 UART
u-blox 6 modules include a Universal Asynchronous Receiver Transmitter (UART) serial interface. RxD1/TxD1
supports data rates from 4.8 to 115.2 kBit/s. The signal output and input levels are 0 V to VCC. An interface
based on RS232 standard levels (+/- 12 V) can be realized using level shifters such as Maxim MAX3232.
Hardware handshake signals and synchronous operation are not supported.
For more information, see the LEA-6 Data Sheet [1], NEO-6 Data Sheet [3],or MAX-6 Data Sheet [11].
1.6.2 USB (LEA-6/NEO-6)
The u-blox 6 Universal Serial Bus (USB) interface supports the full-speed data rate of 12 Mbit/s.
1.6.2.1 USB external components
The USB interface requires some external components in order to implement the physical characteristics required
by the USB 2.0 specification. These external components are shown in Figure 3 and listed in Table 1.
In order to comply with USB specifications, VBUS must be connected through a LDO (U1) to pin VDD_USB of
the module.
If the USB device is self-powered it is possible that the power supply (VCC) is shut down and the Baseband-IC
core is not powered. Since VBUS is still available, it still would be signaled to the USB host that the device is
present and ready to communicate. This is not desired and thus the LDO (U1) should be disabled using the
enable signal (EN) of the VCC-LDO or the output of a voltage supervisor. Depending on the characteristics of the
LDO (U1) it is recommended to add a pull-down resistor (R11) at its output to ensure VDD_USB is not floating if
LDO (U1) is disabled or the USB cable is not connected i.e. VBUS is not supplied.
If the device is bus-powered, LDO (U1) does not need an enable control.
Module
VDD_USB
LDO
VDD_USB
R4
USB_DP
USB_DM
R5
C24 C23
D2
VBUS
DP
DM
GND
USB Device Connector
U1
EN R11
EN
Figure 3: USB Interface
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