OT3m
The OT3m is a standalone Tracker3 variant in a steel enclosure, similar to the OT2m it replaced. It features a USB port and a 10-pin terminal block instead of the OT2m’s RJ12 accessory connector.
The main Tracker3 page contains information common to all Tracker3 models. This page covers details specific to the OT3m.
Connector Pinouts
Male DB9 Serial Connector
| Pin | Function |
|---|---|
| 2 | Data in (port A) |
| 3 | Data out (port A) |
| 4 | Power output for GPS |
| 5 | Ground |
| 7 | Data out (port B) or CTS |
| 8 | Data in (port B) or RTS |
Note: The serial interface is configured as DTE (data terminal equipment) for direct GPS receiver connection. PC connection requires a null modem cable.
Female DB9 RADIO Connector
| Pin | Function |
|---|---|
| 1 | Audio out |
| 2 | COR / Squelch in |
| 3 | PTT out |
| 5 | Audio in |
| 6 | Ground |
| 7 | Power in |
| 8 | PTT in |
Accessory Connector
The OT3m replaces the modular jack used on OT1m and OT2m with a 10-position, 0.150" pitch pluggable screw terminal block.
| Pin | Function |
|---|---|
| 5V | Power output (5V) |
| 1W | Dallas 1-Wire data bus |
| A1 | Analog input 1 |
| A2 | Analog input 2 |
| A3 | Analog input 3 |
| A4 | Analog input 4 |
| CT | Digital counter input |
| IO | Digital I/O |
| PS | Power switch output (7A max) |
| GND | Ground |
- Analog inputs: max 20V
- Digital input (IO): max 5.2V
The IO pin can trigger the 'jumper' option in profile switching. - Grounded = jumper ON - 5V = jumper OFF
Telemetry
When telemetry is enabled, the unit sends packets in the format:
T#sss,V,A1,A2,A3,A4,JC000000
sss: Sequence number (increments each time)V: Supply voltage (tenths of volts)A1–A4: Analog inputsJ: Digital input (IO pin)C: Active config profile
Example: T#012,125,134,120,099,050,10C000000
Power Consumption
Typical draw is ~50 mA. Future firmware versions may reduce this via power-saving features.
Keyboard Interface
Starting with PCB v1.1, the OT3m has a 6-pin mini-DIN connector for a standard PS/2 keyboard.
⚠️ There is no cutout in the case for this connector.
Keyboard input is interpreted as if from a serial terminal, allowing direct message entry without a PC. This feature is currently experimental.