User manual

Table Of Contents
MMP Motherboard
The motherboard contains the interface circuits that translate the signals and commands
passing between the TT8v2, the peripheral components of the system, the system watchdog
circuit and its independent power supply.
The interface circuits protect the system from electrical damage. The eight independent
voltage taps of the main lithium battery pack are diode isolated on the motherboard. Each cell in
the battery pack is internally fused for 3 A. There is an accessible, single-use, 2 A fuse in the
common return of the battery pack. That fuse is physically attached to the pack. Self-resetting
positive temperature coefficient (PTC) “fuses” isolate the three branches of the power distribution
network - (1) the TT8v2, AT8, and motherboard, (2) the sensor suite, and (3) the drive motor.
The branch supplying the drive motor is designed to protect the rest of the power distribution
network from the back EMF voltages that are generated when the motor is driven by the mooring.
This may occur during launch and recovery operations. Wave induced mooring motions,
particularly during storms, may also produce strong, transient, back EMFs. The generated
electrical currents are absorbed through voltage limiting shunt components that can dissipate
several watts.
Digital I/O (DIO) pins, serial communication lines, and analog channels are all protected
from voltage surges by high/low pairs of shunt diodes. DIO lines can be used as either inputs or
outputs. Some can be programmed for special, time dependent, input or output behaviors. In all
cases they can have only two values, 0 V or 5 V, a Logic 0 or a Logic 1. Analog channels
measure analog voltages. The measurement is passed to the micro-processor in digital form and a
dedicated analog channel is used to monitor the voltage of the main lithium battery.
PC and Communications Software
The MMP firmware controls system testing, deployment programming, and data
recovery. The operator enters instructions on the keyboard of a PC running terminal emulation
software and the firmware executes the commands and displays status information and data on
the PC screen.
Laptop and desktop PCs running DOS and Windows are the recommended operating
systems. Handheld PDA’s and PCs with other operating systems can also be used.
The communications link between the MMP and a PC is a standard, 3-wire, full duplex,
RS-232 Electronic Industries Alliance (EIA) connection passing primarily ASCII text bytes. The
communications cable and the terminal emulation software you will need are included in the tool
Appendix B-6