SkyTraq PX1120S - Page 5

5
SkyTraq Technology, Inc. Preliminary Draft www.skytraq.com.tw
14
SPI_MOSI
Not used. Leave unconnected
15
NC
No connection, empty pin
16
SPI_CLK
Not used. Leave unconnected
17
NC
No connection, empty pin
18
SDA
I2C data
19
SCL
I2C clock
20
TXD
UART serial data output, 3.3V LVTTL.
One full-duplex asynchronous serial UART port is implemented. This UART
output is normally used for sending position, time and velocity information
from the receiver in NMEA-0183 format. When idle, this pin output HIGH.
21
RXD
UART serial data input, 3.3V LVTTL.
One full-duplex asynchronous serial UART port is implemented. This UART input
is normally for sending commands or information to the receiver in SkyTraq
binary protocol. In the idle condition, this pin should be driven HIGH. If the
driving circuitry is powered independently of PX1120S, ensure that this pin is
not driven to HIGH when primary power to PX1120S is removed, or a 10K-ohm
series resistor can be added to minimize leakage current from application to
the powered off module.
22
V_BCKP
Backup supply voltage for internal RTC and backup SRAM, 1.3V ~ 3.6V. V_BCKP
must be applied whenever VCC is applied. This pin should be powered
continuously to minimize the startup time. If VCC and V_BCKP are both
removed, the receiver will be in factory default mode upon power up, all user
configuration set is lost. For applications the does not care cold starting every
time, this pin can be connect to VCC.
23
VCC
Main power supply, 3.3V +/- 10%
24
GND
Ground