Rainbow Electronics MAX7358 User Manual
Page 16
MAX7356/MAX7357/MAX7358
1-to-8 I
2
C Bus Switches/Multiplexers with Bus
Lock-Up Detection, Isolation, and Notification
16
______________________________________________________________________________________
B7
B6
B5
B4
B3
B2
B1
B0
COMMAND
X
X
X
X
X
X
X
0
Channel 0 not stuck high
X
X
X
X
X
X
X
1
Channel 0 stuck high
X
X
X
X
X
X
0
X
Channel 1 not stuck high
X
X
X
X
X
X
1
X
Channel 1 stuck high
X
X
X
X
X
0
X
X
Channel 2 not stuck high
X
X
X
X
X
1
X
X
Channel 2 stuck high
X
X
X
X
0
X
X
X
Channel 3 not stuck high
X
X
X
X
1
X
X
X
Channel 3 stuck high
X
X
X
0
X
X
X
X
Channel 4 not stuck high
X
X
X
1
X
X
X
X
Channel 4 stuck high
X
X
0
X
X
X
X
X
Channel 5 not stuck high
X
X
1
X
X
X
X
X
Channel 5 stuck high
X
0
X
X
X
X
X
X
Channel 6 not stuck high
X
1
X
X
X
X
X
X
Channel 6 stuck high
0
X
X
X
X
X
X
X
Channel 7 not stuck high
1
X
X
X
X
X
X
X
Channel 7 stuck high
Table 8. Stuck HIGH Fault Register Channel Indication
X = Don’t care.
ADDRESS
B7
B6
B5
B4
B3
B2
B1
B0
NOTE
0x04
0
1
1
0
1
0
0
0
Write to the troubled device address
0x05
0
1
1
0
0
0
0
0
The first data byte with trailing 0’s due to lock-up
Table 7. A Traffic Prior to Lock-Up Register Contents Example
Stuck HIGH Fault Register
(MAX7357/MAX7358)
Following an interrupt when bit B0 and B7 are enabled,
the bus master can read the stuck high fault byte to
identify stuck channels. A bit set to ”1” indicates that
the associated channel is stuck, and will not be allowed
to be connected to the host bus. The stuck high fault
register is cleared, and, if the interrupt feature is
enabled, RST/INT deasserts (goes to high) once this
register is read. However, while B7 is set to one, any
time a disconnected bus is selected for connection, the
preconnect test runs. If the fault still exists, the fault
handling sequence repeats and the faulty bus will not
be allowed to connect to the host bus.
RST (MAX7356)
The RST on the MAX7356 can be used to reset the
MAX7356 by a host. The RST input is an active-low sig-
nal. By asserting this signal low for a minimum of t
WL(rst)
externally, the MAX7356 resets its I
2
C state machine
and deselects all channels. RST is overvoltage-tolerant
to +6V. The RST input must be connected to V
DD
through a pullup resistor.
RST/INT (MAX7357/MAX7358)
The RST/INT on the MAX7357 or MAX7358 is bidirec-
tional. It can be used to reset the device by a host or by
the device to send an interrupt signal to the host. The
RST/INT input is an active-low signal. By asserting
RST/INT low for a minimum of t
WL(rst)
externally, the
device resets its registers and I
2
C state machine and
deselects all channels. When RST/INT is configured to
notify the host of fault conditions, and while RST/INT
is being used as an output by the MAX7357 or
MAX7358 (sending an interrupt to the host), it does not
function as a reset input. RST/INT is overvoltage-tolerant
to +6V. RST/INT must be connected to V
DD
through a
pullup resistor.
Interrupt Signal (MAX7357/MAX7358)
A bus lock-up-caused interrupt signal can be sent to a
host through the bidirectional RST/INT pin depending
on whether or not bit B0 of the configuration register is
set. Configuration register bit B2 controls how the inter-
rupt signal is reset. When B2 = 0, the interrupt signal
asserts (stays low) until the lock-up indication register is
read. When B2 = 1, the interrupt signal deasserts after