5.3.14 Watchdog
Requires U3 hardware version 1.21. Controls a firmware based watchdog timer. Unattended
systems requiring maxim
um up-time might use this capability to reset the U3 or the entire
ystem. When any of the options are enabled, an internal timer is enabled which resets on any
coming USB communication. If this timer reaches the defined TimeoutPeriod before being
reset, the specified actions will occur. Note that while streaming, data is only going out, so
some other command will have to be called periodically to reset the watchdog timer.
If the watchdog is accidently configured to reset the processor with a very low timeout period
(such as 1 second), it could be difficult to establish any communication with the device. In such
eset-to-default jumper can be used to turn off the watchdog (sets bytes 7-10 to 0).
ower up the U3 with a short from FIO2<=>SCL, then remove the jumper and power cycle the
device again. This also affects the parameters in the ConfigU3 function.
The watchdog settings (bytes 7-10) are stored in non-volatile flash memory, so every call to this
function where settings are written causes a flash erase/write. The flash has a rated endurance
of at least 20000 writes, which is plenty for reasonable operation, but if this function is called in
a high-speed loop the flash could be damaged.
s
in
a case, the r
P
Command:
Byte
0 Checksum8
10xF8
20x05
30x09
4 Checksum16 (LSB)
5 Checksum16 (MSB)
6 WriteMask
Bit 0: Write
7 WatchdogOptions
Bit 5: Reset on Timeout
Bit 4: Set DIO State on Timeout
8-9 TimeoutPeriod
10 DIOConfig
Bit 7: State
Bit 0-4: DIO#
11 Reserved
12 Reserved
13 Reserved
14 Reserved
15 Reserved
104
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