MKY02 User’s Manual
(for Hi-speed Link System)
3 - 12
3.4.2 Packet Error Monitor
The MKY02 has a #LEDRZE pin (pin 45) that outputs a Low level for a given time when any port receives
an error packet. When an LED that goes on at Low level is connected to this #LEDRZE pin, it indicates that
any port of the MKY02 has received an error packet.
This #LEDRZE pin has a drive capability of
±
8 mA.
If the LED can go on even at 8 mA or less, the connec-
tion in Figure 3.11 is possible. In this case, the hard-
ware designer of a HUB needs to determine the values
of current-limiting resistors according to the LED rat-
ing.
To test the LED, the #LEDRZE pin outputs a Low
level for “500000
×
T
AX1
” while a hardware reset is
activated and after the hardware reset is canceled.
The Low pulse output from the #LEDRZE pin is generated by a retriggerable one-shot multivibrator with a
minimum time of “500000
×
T
AX1
(Xi = 48 MHz: 12 Mbps
≈
43.69 ms, 6 Mbps
≈
87.38 ms, 3 Mbps
≈
174.76 ms)”. Therefore, if any of the eight ports receives an error packet again within a given time, the Low
pulse width becomes wide. Even if 12 Mbps is selected as the baud rate of the MKY02, the narrowest time
of the Low pulse is about 43.69 ms and the user can find that the LED is lit.
The red LED to indicating an error should be connected to the #LEDRZE pin. When not used, leave this pin
open.
The #LEDRZE pin may cause the LED to go on the following cases: If the cable con-
nected to the HUB is near its length limit; if impedance mismatch occurs in network cables;
if there is interference including external noise to external the system; Or if an error occurs
in terminals or the center equipment. StepTechnica recommends the user put the LED
where the user can check the LED indicator on the HUB easily.
Summary of Contents for MKY02
Page 1: ...HUB IC MKY02 User s Manual for Hi speed Link System STD HLS02 V1 7E...
Page 8: ...MKY02 User s Manual for Hi speed Link System viii...
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Page 23: ...Chapter 1 Concepts for Using MKY02 HUB 1 15...
Page 24: ...MKY02 User s Manual for Hi speed Link System 1 16...
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Page 60: ...MKY02 User s Manual for Hi speed Link System 4 12...
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Page 70: ...MKY02 User s Manual for Hi speed Link System 5 8 5 3 Package Dimensions...