Uip Isa Address Bus Decoder, Data Bus I/O Latch Cpld, And Communications Circuitry; Control Micro-Stepper Processor, And Sample And Wash Pump Driver Circuitry - Bayer HealthCare RapidPoint 400 Series Service Manual

IC U33 takes the 0 to 5 V levels from the USART and converts them to ±7 V
signals following RS-232C standards. This serial port is used to connect a
bar code reader to the instrument. The connector, J2, is the interface
between the Main board and the Rear Interconnect board located at the
back of the instrument.
UIP ISA Address Bus Decoder, Data Bus I/O Latch CPLD, and
Communications Circuitry
This section Main board contains an IC U20, which is a CPLD. The IC U20
allows expansion of the UIP Processor board using the ISA bus connector.
The LAB-A of the IC inputs the UIP address bus signals, A0 to A9, along
with other ISA control signals such as IOW- and IOR-, to form various chip
select for the other peripherals on the ISA bus.
The LAB-B of IC U20 takes the data bus signals, USD0 to USD3, in and out,
as well as inputs for the FIFO status flags and door and waste switch
signals.
The LAB-C decodes chip selects for the Controller IC and serial port
COM3.
The LAB-D decodes chip selects for FIFO memory interface and buffers
interrupt signals from the FIFO and door/waste switches.
IC U12 takes parallel UIP data and converts it to serial bus protocol.
Control Micro-stepper Processor, and Sample and
Wash Pump Driver Circuitry
This section Main board contains an 87C52 microcontroller, IC U27. The
IC U27 formats data for micro-stepping DAC ICs, U10 and U18. These two
ICs take digital sine and cosine wave data and convert them to analog
voltage reference signals for the power ICs, U4 and U11. These
components work together to give the Main board the ability to drive two
23-frame size stepping motors. The wash pump motor and the sample
pump motor interfaces through connector J3.
88 Rev. C