IRadimed MRidium 3860, Service Manual

Page: 114 / 118

4-10
The MRidium 3860/3860+ is based upon a multi-processor
design, with a main processor for user interface, system wide
functions, dose rate calculations and rate/volume motor
controller computations and communications. This main
processor, a Zilog eZ80 (U3), also watches the function of the
motor control processor(s). Motor control processors, 8051
based, are located on the main processor ( IVPAB002 – U6)
for pump channel A, and within the SideCar, for channel B.
The eZ80 contains 128KB of flash for storage of main system
program code. An additional 512KB of outboard flash holds
additional feature code, such as remote control and export
language data. System code is updated via ‘Data Flash’
memory cards inserted in the memory slot on the back right
side of the pump. This memory is controlled and read/written
via the eZ80 SPI communications buss. A small ‘loader’
resides in the internal flash providing basic code for loading
the larger main code body via SPI, from the data flash socket.
A small loader in the motor controller ( U6 ) accepts download
from eZ80 and writes motor controller code into the 8051
internal flash.
Once power on reset has occurred, the eZ80, running at
22MHz, starts up and initializes both its internal and external
I/O devices. These include real time clock, counter timers,
GPIO lines, SPI, I2C, internal and external (U8) UARTs, A/D
(U5), and LCD display. Once these basic hardware units are
initialized, the main software process begins. Keypad is
continually scanned under 60 Hz interrupt driven timer.
Display output is 8 bit parallel write to J10 via data buss
buffer U7.
On board ( U6) and external ( SideCar ) motor controllers
communicate via SPI buss and unique slave select lines, U9-
12/15. The eZ80 directly monitors all pressure sensors, via
A/D U5, both IV set door switches and motor encoder/
feedback signals. The eZ80 performs the pressure limit, door
open and overall watch dog safety processing.
When user rate and volume data are input via the key pad,
the eZ80 converts these inputs to a time between each
encoder tick, or the time to move the motor 0.36 degrees.
This value and the total VTBI as a total run time value, are
transmitted to the motor controller for channel A or B. The
motor controllers use this information to cause the pump unit
to deliver the programmed rate and volume. Flow rate is
compensated for changes in inlet and outlet pressures to
maintain accuracy. New tick time values are sent each
second to the motor controllers.
During all times, the eZ80 monitors the encoder output from
both the internal pump encoder and the SideCar B pump
encoder, if it is attached. Since the eZ80 ‘knows’ the desired
programmed rate/volume and how much the motor should be
run to achieve this target as well as when the motor should
be turning, the master processor serves as a redundant