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GM-83 User’s manual
7
5 PBRESEN
Manual reset input, ground to reset receiver. Leave floating for normal
operation. The minimum plus width is 150 ms reset signal.
6 GPIO1 General purpose I/O pin 1
7 GPIO2 General purpose I/O pin 2
8 GPIO3 General purpose I/O pin 3
9 GPIO4 General purpose I/O pin 4
10 GND Ground
11 TXA Port A Serial Transmit Data GPS messages.
12 RXA Port A Serial Receive Data GPS commands.
13 GND Ground
14 TXB Port B Serial Transmit Data.
15 RXB Port B Serial Receive Data DGPS messages.
16 GND Ground.
17 GPIO5 Reserved for re-programming flash.
18 GND Ground
19 TIMEMARK 1PPS Time mark output
20 NC No function
1. VCC_5V: + 5V DC voltage input.
2. Dual communication channel TTL levels (GM-83-T/T1/T2) or RS-232 levels (GM-83-A/A1/A2), with
user selectable baud rates (4800-Default, 9600, 19200, 38400).
RXA: Main Receive Channel. This input is used to receive software commands to the GM-83 from user
written software.
RXB: Auxiliary Receive Channel. This input is used to receive serial differential GPS data.
TXA: Main Serial Output. This output provides navigation data to user written software.
TXB: For user’s application (not currently used).
3. PBRESEN: This pin provides an active-low reset input to the GM-83. Activation of this pin will reset
and start acquisition process. It may be left open if not utilized.
4. TIMEMARK: This pin provides One-Pulse-Per-Second output from the GM-83 board, which is
synchronized to GPS time.
This is not available in Trickle-Power mode.
5. VBAT: Battery backup input for powering the RAM and RTC. Typical current is 10uA. Without an
external backup battery the GM-83 will execute a cold start when turning on each time. To achieve
the faster start-up offered by a hot or warm start, either a battery backup must be connected. A 2.5V
and 3.6V power source is required in order to maximize battery lifetime. With a lithium cell battery,
the data retention is 1,000 hours.
6. GPIO Functions: Several I/Os of CPU are connected to the digital interface connector for
customer’s applications and are labeled as GPIO1 to GPIO5.