BCI Advisor, Service Manual

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Chapter 3: Block Level Description
3-6 Advisor
®
Service Manual
Main Board - Communications Port (optional) and Smart Media Interface
The Main Board provides a multi-purpose header connector (J20). This connector supports an optional serial
communications interface board or a Smart Media (Flash) interface board. The serial communications board
provides an isolated RS-232 interface operating at 115.2K Baud, 8-bit data, No parity, 1-start bit, and 1-stop bit.
The output connector is a standard male sub-D DB-9 located at the rear of the Advisor. The service menu allows
selection of several output formats. The service menu also allows new software to be loaded on to the advisor’s
Flash though the serial board.
The Smart Media interface board can also be connected to J20 to update the Advisor’s Flash program memory
(software update). If a serial communications interface option is installed, it must be temporarily removed in
order to perform the software update and then reinstalled afterwards. Both interface boards are electronically
coded so that at power-up, the main processor can recognize which if any are present and proceeds accordingly.
When the Smart Media interface board is detected at power-up, the software update contained in the Smart
Media Flash card is written to the Main board program flash (U22).
Main Board - Front Panel Interface
Signals from the menu knob and pushbuttons on the front of the Advisor are filtered by special hardware,
debounced in the PLD, and passed on to the ARM, either as interrupts or readable data. All signals undergo
Schmitt trigger filtering in addition to RF filtering. The ON/OFF button is routed to the system power supply
where it is used to manually power on the unit.
The battery LED is turned on and off by the Battery Charger Board. The AC LED is powered by the unswitched
power the main board receives. The Battery Charger Board can turn the LED on or off depending on if the
unswitched power is being supplied by AC power or the battery.
Main Board - Critical Failure Alarm System
WARnInG! The AAA battery (BAT2) is a rechargeable alkaline battery. Improper operation and possible
long-term damage may occur if an ordinary alkaline battery (non-rechargeable) is used.
Replace with identical type battery.
The Critical Failure Alarm (CFA) System is a self-sufficient section of circuitry on the Main Board Assembly. During
normal operation, this circuitry maintains its own AAA rechargeable alkaline battery (BAT2), monitors the ARM7
microprocessor for proper operation, and monitors the main +12 Volt power source from which all circuitry is
ultimately powered. An unintentional loss of power (non-user initiated standby/shutdown), or improper ARM7
microprocessor execution (or lack thereof) results in a constant tone audio alarm signal. This technical alarm
state will persist for at least 20 minutes with a fully charged battery. The alarm state is cleared when power is
restored, or the front-panel audio silence key is activated, or the battery is completely discharged.
The CFA micro controller (U63) handles the monitoring and battery charging functions. ARM7 microprocessor
activity is conveyed to the CFA micro controller (U63-4) by signal ARM_COMM. A user-initiated standby/
shutdown is communicated in advance to the CFA micro controller so that the CFA will properly interpret the
subsequent loss of ARM7 activity as an intended standby/shutdown state. During normal operation, if the CFA
detects an unintended loss of ARM7 microprocessor activity, the CFA initiates an alarm. The main +12 Volt power
source (UNSW_PWR) is scaled by R252 and R250, buffered by op amp (U62A), and monitored by the CFA micro
controller (U63-7). If the +12V power source falls below approximately 9Volts DC, the CFA initiates an alarm.
The CFA micro controller initiates an alarm by asserting a logic high to Q21-1, which is latched by NAND gates
U66 and U67. The latched alarm state can be cleared (reset) by the CFA micro controller or the front-panel audio
silence button by asserting a logic low at voltage detector input U65-2.
The AAA rechargeable alkaline battery state is monitored by way op amp U62B and when necessary, charged
by pulsing Q22. Mosfet Q26 provides reverse battery protection should a replacement battery be installed
backwards. Voltage regulator U61 supplies 3.3V power while voltage detector U64 acts as power supply
supervisor, resetting the CFA micro controller if the 3.3V power falls below 2.7 Volts DC.