Difference between revisions of "OT3m"

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Revision as of 20:45, 22 December 2012

OT3m with terminal block

The OT3m is a standalone Tracker3 variant in a steel enclosure, similar to the OT2m it replaces. As of 4 January 2012, the Tracker3 firmware duplicates the functionality of the OT2m, with the addition of USB support and changes to the telemetry system. Future firmware releases will add new functionality not possible on the Tracker2.

The main Tracker3 page covers information relevant to all Tracker3 variants. This page contains only information specific to the OT3m model.

Accessory Connector

In place of the modular jack used on the OT1m and OT2m, the OT3m has a 10-position, 0.150" pitch pluggable screw terminal block. Pinouts, from left to right, are as follows:

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 (7 amps max)
GND Ground

The analog inputs should not exceed 20 volts, and the digital input should not exceed 5.2 volts.


When the telemetry function is enabled, a telemetry packet is sent with the following format:


"sss" is the telemetry sequence number (incremented with each transmission), V is the supply voltage, A1-A4 are the corresponding analog inputs on the accessory connector, J is the status of the digital input marked IO, and C is the configuration profile in use.

All analog values are given in tenths of a volt, e.g. 12.5 volts is shown as 125.

Power Consumption

The OT3m currently draws approximately 50 mA. Future firmware revisions will reduce this as more power saving software functions are implemented.

Keyboard Interface

Starting with PCB version 1.1, the OT3m board has a 6-pin mini-DIN connector that allows connection of a standard PS/2 keyboard. Note that there is no opening in the enclosure for this connector. Presently keyboard input is interpreted the same as input from a serial terminal, so a keyboard can be used to enter commands and send messages without a PC. Keyboard support is currently considered to be an experimental feature.