Kontron COMe-cP2020 - Manual (Page 21)

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COMe-P2020 User Guide
21
The four operational Watchdog timer modes can be configured by the WMD[1:0] bits, and are described as follows:
Timer only mode - In this mode the Watchdog is enabled using the required timeout period. Normally, the Watchdog is
retriggered by writing a ‘1’ to the WTR bit. In the event a timeout occurs, the WTE bit is set to ‘1’. This bit can then be polled
by the application and handled accordingly. To continue using the Watchdog, write a ‘1’ to the WTE bit, and then retrigger
the Watchdog using WTR. The WTE bit retains its setting as long as no power down-up is done. Therefore, this bit may be
used to verify the status of the Watchdog.
Reset mode - This mode is used to force a hard reset in the event of a Watchdog timeout. In addition, the WTE bit is not reset
by the hard reset, which makes it available if necessary to determine the status of the Watchdog prior to the reset.
Interrupt mode - This mode causes the generation of an interrupt in the event of a Watchdog timeout. The interrupt han-
dling is a function of the application. If required, the WTE bit can be used to determine if a Watchdog timeout has occurred.
Dual stage mode - This is a complex mode where in the event of a timeout two things occur: 1) an interrupt is generated,
and 2) the Watchdog is retriggered automatically. In the event a second timeout occurs following the first timeout, a hard
reset will be generated. The second timeout period is the same as the first. If the Watchdog is retriggered normally as spec-
ified above, operation continues. The interrupt generated at the first timeout is available to the application to handle the
first timeout if required. As with all of the other modes, the WTE bit is available for application use.
Pin B27 on the COM Express® J1 connector offers a signal that can be asserted when a Watchdog timer has not been trig-
gered within time. It can be configured to any of the 2 stages. Deassertion of the signal is automatically done after reset. If
deassertion during runtime is necessary please contact Kontron for further assistance.
2.5 Connectors
2.5.1 COM Express Connectors
Table 2-1: Connector J1 Row A Pinout
PIN SIGNAL
SIGNAL
GROUP
TYPE TERMINATION COMMENT
A1 GND PWR GND
A2 GBE0_MDI3- GigE MDI DP-I/O eTSEC1_GBE0_MDI3-
A3 GBE0_MDI3+ GigE MDI DP-I/O eTSEC1_GBE0_MDI3+
A4 GBE0_LINK100# GigE MDI O-3.3 eTSEC1_GBE0_LINK100#
A5 GBE0_LINK1000# GigE MDI O-3.3 eTSEC1_GBE0_LINK1000#
A6 GBE0_MDI2- GigE MDI DP-I/O eTSEC1_GBE0_MDI2-
A7 GBE0_MDI2+ GigE MDI DP-I/O eTSEC1_GBE0_MDI2+
A8 GBE0_LINK# GigE MDI O-3.3 eTSEC1_GBE0_LINK#
A9 GBE0_MDI1- GigE MDI DP-I/O eTSEC1_GBE0_MDI1-
A10 GBE0_MDI1+ GigE MDI DP-I/O eTSEC1_GBE0_MDI1+
A11 GND PWR GND
A12 GBE0_MDI0- GigE MDI DP-I/O eTSEC1_GBE0_MDI0-
A13 GBE0_MDI0+ GigE MDI DP-I/O eTSEC1_GBE0_MDI0+
A14 GBE0_CTREF GigE MDI Not applicable
A15 SUS_S3# BOARD CTRL O-3.3 Undef ined
A16 SATA0_TX+ SATA N/C
A17 SATA0_TX- SATA N/C
A18 SUS_S4# BOARD CTRL O-3.3 Undef ined
A19 SATA0_RX+ SATA N/C
A20 SATA0_RX- SATA N/C
A21 GND PWR GND
A22 SATA2_TX+ SATA N/C
A23 SATA2_TX- SATA N/C
A24 SUS_S5# BOARD CTRL O-3.3 Undef ined
A25 SATA2_RX+ SATA N/C
A26 SATA2_RX- SATA N/C