On-Board I/O Signals; Control/Monitor Communication; Power-Up Behavior; Operating Modes - ConMed Hyfrecator 2000 Service Manual

2000

3.3.2.6 On-Board I/O Signals

• /φ1, /φ2 - Two-bit grey-coded rotary encoder output (power adjust).
• SDA, SCL - IIC serial EEPROM data and clock signals (.C & .M)
• VCAL - Three-state analog signal representing Service jumper (J2) presence (0.0V), normal run (+5.0V)
or Monitor microcontroller fault status (+2.5V) to Control microcontroller.
• VGATE - Driven by GATEMON analog duty cycle monitor signal. Nominally +2.1 to 2.6 V ,
GATE active.
• /GATE.M - Isolated version of /GATE; used for PA drive frequency monitor.
• GATENA - Monitor GATE enable; forces PA drive off via Q3 when low.
• PSETO.0:7 - LED segment drive and Control-to-Monitor settings/fault code signal bus.
• LED1:8 - LED anode drive, current limited by RN1.
• LED1S - Ones LED digit drive.
• LED10S - Tens LED digit drive.
• /GATEPWM - PA gate drive signal; frequency and duty cycle determined by Mode selection.
• HVPWM - Variable duty cycle CMOS signal; same frequency as /GATEPWM. Sets HV voltage per
power setting. (see VCON above).
• VMODE - Three-state analog representation of Mode switch position.

3.3.2.7 Control/Monitor Communication

The two microcontrollers communicate with one another via three paths:
• Functional ESU Signals: i.e, HV voltage, gate frequency, duty cycle, and tone generation. Direction is
from Control to Monitor.
• 10-bit LED drive bus (PSETO0:7, LED1S, and LED10S): Direction is from Control to Monitor during
normal Run Mode. During POST and Fault Code display, the direction is from Monitor to Control.
• VCAL Signal: From Monitor to Control. Upon detecting a fault,the Monitor pulls VCAL.M to ground,
and through the voltage divider formed by RN4A and RN4B, causes VCAL.C to go to about 2.5 VDC.

3.3.3 Power-Up Behavior

When power is applied, +5M and +5C will rise towards their regulated voltage levels. These voltages are
presented to the /MCLR (Master Clear) inputs of each microcontroller. After reaching about +4.2 Vdc, and
each microcontroller 4 MHz clock oscillator has started, the microcontrollers begin executing their programs
stored in on-board program memory. These programs set up I/O ports, read and validate data from their
respective non-volatile EEPROMS, and perform some error-detection processes, such as stuck-on faults on
any of the three accessory button signals, /ACTIVE, /PWDN and /POWUP .
Both microcontrollers then check their VCAL inputs to determine which operating mode to enter.

3.3.4 Operating Modes

The Hyfrecator® 2000 can power up in either of two modes, Run or Service.
• Run Mode: Used in normal clinical service.
• Service Mode: Accessible only when the unit's enclosure is opened.
14