MC9S08DZ60MLF Datasheet, PDF (262/416 Pages) Freescale Semiconductor, Inc – MC9S08DZ60 Series Features

Chapter 12 Freescale’s Controller Area Network (S08MSCANV1)
12.5.4.3 Emulation Modes
In all emulation modes, the MSCAN module behaves just like normal system operation modes as
described within this specification.
12.5.4.4 Listen-Only Mode
In an optional CAN bus monitoring mode (listen-only), the CAN node is able to receive valid data frames
and valid remote frames, but it sends only “recessive” bits on the CAN bus. In addition, it cannot start a
transmision. If the MAC sub-layer is required to send a “dominant” bit (ACK bit, overload flag, or active
error flag), the bit is rerouted internally so that the MAC sub-layer monitors this “dominant” bit, although
the CAN bus may remain in recessive state externally.
12.5.4.5 Security Modes
The MSCAN module has no security features.
12.5.4.6 Loopback Self Test Mode
Loopback self test mode is sometimes used to check software, independent of connections in the external
system, to help isolate system problems. In this mode, the transmitter output is internally connected to the
receiver input. The RXCAN input pin is ignored and the TXCAN output goes to the recessive state (logic
1). The MSCAN behaves as it does normally when transmitting and treats its own transmitted message as
a message received from a remote node. In this state, the MSCAN ignores the bit sent during the ACK slot
in the CAN frame acknowledge field to ensure proper reception of its own message. Both transmit and
receive interrupts are generated.
12.5.5 Low-Power Options
If the MSCAN is disabled (CANE = 0), the MSCAN clocks are stopped for power saving.
If the MSCAN is enabled (CANE = 1), the MSCAN has two additional modes with reduced power
consumption, compared to normal mode: sleep and power down mode. In sleep mode, power consumption
is reduced by stopping all clocks except those to access the registers from the CPU side. In power down
mode, all clocks are stopped and no power is consumed.
Table 12-36 summarizes the combinations of MSCAN and CPU modes. A particular combination of
modes is entered by the given settings on the CSWAI and SLPRQ/SLPAK bits.
For all modes, an MSCAN wake-up interrupt can occur only if the MSCAN is in sleep mode (SLPRQ = 1
and SLPAK = 1), wake-up functionality is enabled (WUPE = 1), and the wake-up interrupt is enabled
(WUPIE = 1).
MC9S08DZ60 Series Data Sheet, Rev. 4
262
Freescale Semiconductor