L50 Hardware Design
L50_HD_V1.0 -25-
Figure 12: I2C design reference for L50 module
3.7.3 SPI Interface
The Serial Peripheral Interface (SPI) provides access to a flexible, full-duplex synchronous serial bus.
However, L50 doesn’t support SPI at present.
3.8
Assisted GPS
By supplying aided information like ephemeris, almanac, rough last position, time and satellite status,
A-GPS can help
improve TTFF and the acquisition sensitivity of the GPS receiver.
L50 supports one kind of A-GPS called Client Generated Extended Ephemeris (CGEE) which ensures
fast TTFF out to 3 days .The CGEE data is generated internally from satellite ephemeris as a
background task, and then L50 collects ephemeris from as many satellites as possible before entering
Hibernate mode.
The CGEE functionality requires that VIO/RTC power supply is kept active all the time and an
external 1Mbit EEPROM connected to DR_I2C bus for CGEE data storage. The recommended
EEPROMs are in the following table and they are verified.
Table 10: Recommended EEPROMs
Manufacturer
Part Number
ST
M24M01
Seiko Instruments Inc.
S-24CM01C
Atmel
AT24C1024B
Note: The part number which we recommend is a series part number, please get more details from
the datasheet such as operation voltage and package.
Table 11: Pin definition of the DR_I2C interfaces
Interface
Name
Pin
Function
Dead Reckoning
I2C Interface
DR_I2C_DIO
21
I2C data (SDA)
DR_I2C_CLK
22
I2C clock (SCL)
The DR_I2C_DIO and DR_I2C_CLK pins are open-drain output and should be pulled up to VDD
which depends on the EEPROM’s operation voltage externally by 2K resistors to meet requirement of
maximum data rate up to 400Kbs. The following circuit is the reference design for L50 and EEPROM.
Quectel
Preliminary
