DS271PP3
107
CS8900A
Crystal LAN™ ISA Ethernet Controller
CIRRUS LOGIC PRODUCT DATA SHEET
6.1 Boundary Scan
Boundary Scan test mode provides an easy and ef-
ficient board-level test for verifying that the
CS8900A has been installed properly. Boundary
Scan will check to see if the orientation of the chip
is correct, and if there are any open or short circuits.
Boundary Scan is controlled by the TEST pin.
When TEST is high, the CS8900A is configured
for normal operation. When TEST is low, the fol-
lowing occurs:
•
the CS8900A enters Boundary Scan test mode
and stays in this mode as long as TEST is low;
•
the CS8900A goes through an internal reset and
remains in internal reset as long as TEST is
low;
•
the AEN pin, normally the ISA bus Address
Enable, is redefined to become the Boundary
Scan shift clock input; and
•
all digital outputs and bi-directional pins are
placed in a high-impedance state (this electri-
cally isolates the CS8900A digital outputs from
the rest of the circuit board).
For Boundary Scan to be enabled, AEN must be
low before TEST is driven low.
A complete Boundary Scan test is made up of two
separate cycles. The first cycle, known as the Out-
put Cycle, tests all digital output pins and all bi-di-
rectional pins. The second cycle, known as the
Input Cycle, tests all digital input pins and all bi-di-
rectional pins.
6.1.1 Output Cycle
During the Output Cycle, the falling edge of AEN
causes each of the 17 digital output pins and each
of the 17 bi-directional pins to be driven low, one
at a time. The cycle begins with LINKLED and ad-
vances in order counterclockwise around the chip
through all 34 pins. This test is referred to as a
"walking 0" test.
The following is a list of output pins and bi-direc-
tional pins that are tested during the Output Cycle:
The output pins not included in this test are:
6.1.2 Input Cycle
During the Input Cycle, the falling edge of AEN
causes the state of each selected pin to be trans-
ferred to EEDataOut (that is, EEDataOut will be
high or low depending on the input level of the se-
lected pin). This cycle begins with SLEEP and ad-
vances clockwise through each of 33 input pins (all
digital input pins except for AEN) and each of the
17 bi-directional pins, one pin at a time.
The following is a list of input pins and bi-direc-
tional pins that are tested during the Input Cycle:
Pin Name
Pin #
Pin Name
Pin #
ELCS
2
INTRQ1
31
EECS
3
INTRQ0
32
EESK
4
IOCS16
33
EEDataOut
5
MEMCS16
34
DMARQ2
11
INTRQ3
35
DMARQ1
13
IOCHRDY
64
DMARQ0
15
SD0 - SD7 65-68, 71-74
CSOUT
17
BSTATUS
78
SD08-SD15 27-24, 21-18
LINKLED
99
INTRQ2
30
LANLED
100
Table 38.
Pin Name
Pin #
Pin Name
Pin #
DO+
83
TXD-
88
DO-
84
RES
93
TXD+
87
XTAL2
98
Table 39.
Pin Name
Pin #
Pin Name
Pin #
ELCS
2
SBHE
36
EEDataIn
6
SA0 - SA11
37-48
CHIPSEL
7
REFRESH
49
DMACK2
12
SA12 - SA19 50-54, 58-60
DMACK1
14
IOR
61
DMACK0
16
IOW
62
SD08-SD15 27-24, 21-18
SD0 - SD7
65-68, 71-74
MEMW
28
RESET
75
MEMR
29
SLEEP
77
Table 40.
Содержание Crystal LAN CS8900A
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