GEM1111

GEM1111 - 1616A00

GEM1111

1. Overview

GEM1111 is a high-performance L1 GNSS positioning module with antenna built-in, which is developed on the base of the state-of-the-art Allystar Cynosure III Lite architecture.
It supports global civil navigation systems, including GPS, BDS, GLONASS, Galileo, and QZSS. Featured with SAW and LNA, GEM1111 achieves high positioning accuracy and short TTFF, especially in a rough urban environment.
It supports antenna supervisor and auto-switching between the built-in antenna and the external antenna. With a compact body and high performance, GEM1111 is widely applied to tracking applications, like automotive, consumer, and industrial tracking.

1.2 Feature

• Supports GPS, BDS, Galileo, GLONASS, and QZSS systems Built-in LNA & SAW for better sensitivity
• Supports A-GNSS
• Supports geo-fence function
• Ultra-low power consumption around 13 mA in tracking mode
• Supports antenna supervision
• Supports auto-switching between the built-in antenna and the external antenna

1.1 Specifications

Parameters	Specification
GNSS tracking channels	72 channels, GPS/QZSS: L1C/A Galileo: E1 GLONASS: L1
Updating rate	1 Hz (Default), up to 5 Hz
Position accuracy	< 1.5 m CEP @ Open Sky
Velocity accuracy	0.1 m/s CEP
Time accuracy	1PPS 20ns
Time to First Fix(TTFF)	Hot start 1S Cold star 28S
Sensitivity	Cold start -149 dBm Reacquisition -159dBm Tracking -163dBm
Power supply	2.0-3.63 V, Typical 3.3 V
Power consumption	Acquisition 15mA @3.3V Tracking 13mA @3.3V Standby mode 10uA
Serial Interface	UART Default: 115200 bps
Protocol	NMEA 0183 Protocol Ver.3.01/4.00 (Default)/4.10
Operating temperature	-40~+85℃
Storage temperature	-40~+85℃
Weight	7.5g
Dimessions	16*16*6.9mm

2.Pin description

2.1 Pin assignment

2.2 Detailed pin description

Function	Symbol	No	I/O	Decription
Power	VDD	4	Power	Main power supply voltage input.
	GND	3,12	VSS	Ground
	AVDD_BAK	5	Power	Backup power supply voltage input. Backup power is needed in order to enable warm and hot start features. Backup power is a must for the system to work. If no backup power is available, connect AVDD_BAK to the main power supply.
Antenna	RF_IN	11	I	RF signal input. Use a controlled impedance of 50 for the routing from RF_IN pin to the antenna or the antenna connector.
UART	TXD0	2	O	UART0 serial data Tx.
	RXD0	1	I	UART0 serial data Rx.
Other	PRTRG	7	I	Mode selection or the trigger input in deep sleep mode to wake up the system.
	RESET	10	I	External reset, low active
	1 PPS	6	O	Setting for time pulse output (PPS). Leave it floating if not used.
	AADET_N	8	O	Active antenna detection
	NC	9		Reserved. Leave it floating if not used.

3.ELECTRICAL CHARACTERISTICS

3.1 Absolute Maximum Rating

Symbol	Parameter	Min.	Max.	Unit
VDD	Power input for the main power domain	-0.5	3.6	V
AVDD_BAK	Power input for the backup power domain	-0.5	3.6	V
VImax	Digital I/O pin input voltage	-0.5	3.6	V
Tstorage	Storage temperature	-40	85	°C
Tsolder	Solder reflow temperature	--	260	°C

3.2 IO Characteristics

3.2.1 PRRSTX and PRTRG

Symbol	Parameter	Condition	Min.	Typ.	Max.	Unit
IIZ	Input leakage current	--	--	--	+/-1	uA
VIH	Input high voltage	--	AVDD_BAK*0. 67	--	AVDD_BAK	V
VIL	Input low voltage	--	0	--	AVDD_BAK*0.27	V
VOH	Output high voltage	IOH=5.3 mA, AVDD_BAK=3.3V	2.64	--	--	V
IOH=1.2 mA, AVDD_BAK=1.8V	1.53	--	--	V
VOL	Output low voltage	IOL=3.9 mA, AVDD_BAK=3.3V	--	--	0.4	V
IOL=1.9 mA, AVDD_BAK=1.8V	--	--	0.45	V
Ci	Input capacitancee	--	--	--	11	pF
RPU	Pull-up resistance	--	35	--	84	kΩ

3.2.2 Others

Symbol	Parameter	Condition	Min.	Typ.	Max.	Unit
IIZ	Input leakage current	--	--	--	+/-1	uA
VIH	Input high voltage	--	VDD*0.67	--	VDD	V
VIL	Input low voltage	--	0	--	VDD*0.27	V
VOH	Output high voltage	IOH =5.3 mA, VDD=3.3V	2.64	--	--	V
VOL	Output low voltage	IOL =3.9 mA, VDD=3.3V	--	--	0.4	V
Ci	Input capacitance	--	--	--	11	pF

3.3 DC Characteristics

3.3.1 Operating Conditions

Symbol	Parameter	Min.	Typ.	Max.	Unit
VDD	Power supply voltage	3.0	3.3	3.6	V
AVDD_BAK	Backup battery voltage	1.6	3.3	3.6	V
ICCmax	Maximum operating current @ VDD	--	--	200	mA
Tenv	Operating temperature	-40	--	85	°C

3.3.2 Power Consumption

Parameter	Measure Pin	Typ.	Unit
Average tracking current（GNSS）	VDD[1]	33	mA
Standby mode	AVDD_BAK[2]	14	uA

• [1] Condition: V_DD=3.3_V@Room Temperature. All Pins Open. GNSS=GPS+Galileo+GLONASS+QZSS+SBAS
• [2] Condition: AV_DD_BAK=3.3_V@Room Temperature. All Pins Open.

4. HARDWARE DESCRIPTION

4.1 Connecting Power

In order to ensure positioning performance, please control the ripple of the module power supply.

It is recommended to use the LDO with a max output current above 100mA.

If the power for the VDD pin is off, the real-time clock (RTC) and battery-backed RAM (BBR) is supplied through the AVDD_BAK pin. Thus, orbit information and time can be maintained and will allow a Hot or Warm start.

Note: If no backup supply is available, connect the AV_DD_BAK pin to the main power supply. The floating state is not recommended.

4.2 Internal Antenna

GEM1111-1818A00 provides a 18x18mm internal antenna.

4.3 Reset and Mode control

The operation mode of the GNSS module is controlled by PRRSTX (nRESET) and PRTRG (BOOT) pin. While the module works in normal operation, leave PRRSTX and PRTRG pins floating if there is no upgrading or reset demands, or others. Keep PRTRG pin floating during system power-up or the external reset (PRRSTX from low to high), and the module will enter User Normal Mode. When the module powers up or PRRSTX from low to high, the module will execute an external reset.

(If the power for AVDD_BAK is always on, the external reset will not affect the ephemeris data in the backup domain) Drive PRTRG pin to low or connect PRTRG to GND directly (not by pull-down resistance) during system power-up or the external reset (PRRSTX from low to high), and the system enters BootROM Command Mode at PRTRG pin being released from low to floating state, and ready for firmware upgrading command. When connecting PRRSTX and PRTRG to any host IO, DO NOT use the pull-up or pull-down resistance.