TTCAN | User’s Manual | Revision 1.6 |
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LBack | Loop Back Mode | |
| one | Loop Back Mode is enabled. |
| zero | Loop Back Mode is disabled. |
Silent | Silent Mode | |
| one | The module is in Silent Mode |
| zero | Normal operation. |
NoRAM | No Message RAM Mode | |
| one | IF1 Registers used as Tx Buffer, IF2 Registers used as Rx Buffer. |
| zero | No Message RAM Mode disabled, normal Message RAM usage. |
WdOff Disable Watchdog
one The Watchdog disabled.
zero The Watchdog is enabled, after Initialization has finished (Init = 0).
Write access to the Test Register is enabled by setting bit Test in the CAN Control Register. The different test functions may be combined, but
2.3.4.2 Disable Watchdog Mode
The TT Application Watchdog (see chapter 3.5.6) can be disabled by programming the Test Register bit WdOff to one and the Application_Watchdog_Limit AppWdL to 0x00. When bit Test in the CAN Control Register is reset, WdOff is also reset if the TTCAN is in time triggered operating mode; if the TTCAN is in event driven CAN mode, WdOff is remains set and the TT Application Watchdog remains disabled (emulating the C_CAN function).
The TT Application Watchdog should not be disabled in a TTCAN application program.
2.3.4.3 Silent Mode
The CAN_Core can be set in Silent Mode by programming the Test Register bit Silent to one.
In Silent Mode, the TTCAN is able to receive valid data frames and valid remote frames, but it sends only recessive bits on the CAN bus and it cannot start a transmission. If the CAN_Core is required to send a dominant bit (ACK bit, overload flag, active error flag), the bit is rerouted internally so that the CAN_Core monitors this dominant bit, although the CAN bus may remain in recessive state. The Silent Mode can be used to analyse the traffic on a CAN bus without affecting it by the transmission of dominant bits (Acknowledge Bits, Error Frames). Figure 2 shows the connection of signals CAN_TX and CAN_RX to the CAN_Core in Silent Mode.
CAN_TX CAN_RX
TTCAN =1
• •
Tx Rx
CAN_Core
Figure 2: CAN_Core in Silent Mode
In ISO 11898-1, the Silent Mode is called the Bus Monitoring Mode.
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