Theory of Operation
Introduction
2
2-9
This particular series of devices is presently available in 2 other sizes, 8 MB and 16 MB,
provisions have been made in this design for using those devices if necessary, with
minimal required rework. U20 is programmed and powered from Vcc, there is no
additional 12 V programming voltage required for Strataflash devices. Support is
provided, in the form of bus transceivers and daughter card connector (U4, 5, 10, 28, 29,
and P4), for a single PCMCIA slot. The timing and control of the PCMCIA slot is
internal to the microprocessor. The hardware on both the 4004 and 4041 PCAs will
support all types of type I and type II PCMCIA cards, however the firmware will only
support ATA Flash Memory PC-Cards.
Serial Devices
The 268XA controller supports several serial device types, 10/100 Base T Ethernet,
RS-232 and multiple SPI devices. These peripherals are described on page 3 of the 1004
schematic.
The Ethernet functionality is split between the physical layer transceiver (PHY) and the
microprocessor, which houses the MAC layer and various application layers. The
interface between the 2 devices is an industry standard MII port. The PHY device (U17),
an AMD 79C874, autonegotiates the Ethernet link speed to either 10 Base Tx or 100
Base Tx, as well as either half or full duplex, depending on the capabilities of the hub that
it is talking with. This is transparent to both the firmware and the user. The PHY will
attempt to use the fastest mode, full duplex 100 Base Tx, as default and negotiate down in
capability if necessary. The LED labeled LNK on the rear panel of the 268XA chassis is
a link/speed indicator. It will be green if in 100 Base T mode or red if in 10 Base T mode.
There is no duplex or collision indication LED.
There are 2 RS-232 ports on the 268XA controller board. One of them is user accessible
from the rear panel at connector P1, and the other (P5) is for development and debug
only. P1 is an industry standard Male DB9 connector. The modem control signals RTS,
DTR, CTS and DSR are available for use from P1. P5 is a 3 pin mate-n-lok type
connector and requires a special cable assembly in order to use. The MAC address, serial
number, IP address and other sensitive boot configuration information may be changed
from this port. Great care should be used when accessing the 268XA through the P5
RS-232 console port.
The SPI devices in the 268XA system are the display controller on the 45-3201 PCA, and
one 2KBit EEPROM per module slot for calibration. These devices all share a common 3
wire synchronous interface, with only one device occupying the SPI bus at any given
time. The microprocessor is always the master, and addresses each SPI device
independently with a dedicated chip select. The calibration EEPROMs reside on the
module power supply PCA (268XA-4031) within each module, see section 5 below for
details.
Trigger In/Out, Master Alarm
The trigger in and trigger out functionality is shared by the microprocessor and the fpga.
The master alarm output, which is set by the firmware for as long as an alarm condition
occurs, is an inverted and protected version of a general purpose microprocessor port pin.
The MPC855 writes to a specific address in the gate array when a trigger out pulse is
required. The fpga then drives an output pin low and starts a timer for the requisite
125
µ
s pulse. The trigger input to the microprocessor is a buffered version of the trigger
input from the external world. This is necessary because the microprocessor only has
falling edge interrupts, and it needs to be interrupted on both edges of the trigger input
signal. So, when the trigger input goes low, the microprocessor tells the fpga to invert the
signal that it sees so that when the global trigger in signal goes high, the microprocessor
will see another falling edge interrupt, as required.
Summary of Contents for 2680A
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Page 204: ...268XA Service Manual 7 10 268X FINAL ASSEMBLY alg105f eps Figure 7 1 268XA Final Assembly ...
Page 207: ...Replaceable Parts Parts Lists 7 7 13 2680A DIO alg100f eps Figure 7 3 DIO Module ...
Page 209: ...Replaceable Parts Parts Lists 7 7 15 2680A FAI alg102f eps Figure 7 4 FAI Module ...
Page 211: ...Replaceable Parts Parts Lists 7 7 17 2680A PAI alg103f eps Figure 7 5 PAI Module ...
Page 214: ...268XA Service Manual 8 2 ...
Page 215: ...8 3 8 Schematic Diagrams Figure 8 1 Backplane PCA 2680A 4001 ...
Page 216: ...268XA Service Manual 8 4 Figure 8 1 Backplane PCA cont 2680A 1001 ...
Page 217: ...8 5 8 Schematic Diagrams Figure 8 2 Controller System Power PCA 2680A 4004 ...
Page 223: ...8 11 8 Schematic Diagrams Figure 8 3 Digital I O PCA 2680A 4006 ...
Page 224: ...268XA Service Manual 8 12 Figure 8 3 Digital I O PCA cont 2680A 1006 1 of 3 ...
Page 225: ...8 13 8 Schematic Diagrams Figure 8 3 Digital I O PCA cont 2680A 1006 2 of 3 ...
Page 226: ...268XA Service Manual 8 14 Figure 8 3 Digital I O PCA cont 2680A 1006 3 of 3 ...
Page 227: ...8 15 8 Schematic Diagrams Figure 8 4 Backplane Extender PCA 2680A 4009 ...
Page 228: ...268XA Service Manual 8 16 Figure 8 4 Backplane Extender PCA cont 2680A 1009 ...
Page 229: ...8 17 8 Schematic Diagrams Figure 8 5 Extender PCA 2680A 4010 ...
Page 230: ...268XA Service Manual 8 18 Figure 8 5 Extender PCA cont 2680A 3010 ...
Page 231: ...8 19 8 Schematic Diagrams Figure 8 6 A D Supply Assembly 2680A 4031 ...
Page 232: ...268XA Service Manual 8 20 Figure 8 6 A D Supply Assembly cont 2680 1031 ...
Page 233: ...8 21 8 Schematic Diagrams Figure 8 7 PCMCIA PCA 2680A 4041 ...
Page 234: ...268XA Service Manual 8 22 Figure 8 7 PCMCIA PCA cont 2686 1041 ...
Page 235: ...8 23 8 Schematic Diagrams Figure 8 8 Output PCA 2680A 4062 ...
Page 236: ...268XA Service Manual 8 24 Figure 8 8 Output PCA cont 2680A 1062 ...
Page 237: ...8 25 8 Schematic Diagrams Figure 8 9 A D PFE PCA 2640A 4003 ...
Page 238: ...268XA Service Manual 8 26 Figure 8 9 A D PFE PCA cont 1 of 6 ...
Page 239: ...8 27 8 Schematic Diagrams Figure 8 9 A D PFE PCA cont 2 of 6 ...
Page 240: ...268XA Service Manual 8 28 Figure 8 9 A D PFE PCA cont 2640A 1003 3 of 6 ...
Page 241: ...8 29 8 Schematic Diagrams Figure 8 9 A D PFE PCA cont 2640A 1003 4 of 6 ...
Page 242: ...268XA Service Manual 8 30 Figure 8 9 A D PFE PCA cont 2640A 1003 5 of 6 ...
Page 243: ...8 31 8 Schematic Diagrams Figure 8 9 A D PFE PCA cont 2640A 1003 6 of 6 ...
Page 244: ...268XA Service Manual 8 32 Figure 8 10 A D FFE PCA 2645A 4003 ...
Page 245: ...8 33 8 Schematic Diagrams Figure 8 10 A D FFE PCA cont 2645A 1003 1 of 6 ...
Page 246: ...268XA Service Manual 8 34 Figure 8 10 A D FFE PCA cont 2645A 1003 2 of 6 ...
Page 247: ...8 35 8 Schematic Diagrams Figure 8 10 A D FFE PCA cont 2645A 1003 3 of 6 ...
Page 248: ...268XA Service Manual 8 36 Figure 8 10 A D FFE PCA cont 2645A 1003 4 of 6 ...
Page 249: ...8 37 8 Schematic Diagrams Figure 8 10 A D FFE PCA cont 2645A 1003 5 of 6 ...
Page 250: ...268XA Service Manual 8 38 Figure 8 10 A D FFE PCA cont 700p29_topress zip 2645A 1003 6 of 6 ...
Page 251: ...8 39 8 Schematic Diagrams Figure 8 11 Analog Input Connector PCA 2620A 4004A ...
Page 252: ...268XA Service Manual 8 40 2620A 1004 Figure 8 11 Analog Input Connector PCA cont ...
Page 253: ...8 41 8 Schematic Diagrams Figure 8 12 Display PCA 1 of 1 ...
Page 254: ...268XA Service Manual 8 42 Figure 8 12 Display PCA cont 1 of 1 ...