Functional Description and Application Information
Die-to-Die Initiator (D2DIV1)
MM912F634
Freescale Semiconductor
312
Figure 98. D2D Internal Interrupts
4.37.5
Initialization Information
During initialization the transfer width, clock divider and timeout value must be set according to the capabilities of the target device
before starting any transaction. See the D2D Target specification for details.
4.37.6
Application Information
4.37.6.1
Entering low power mode
The D2DI module is typically used on a microcontroller along with an analog companion device containing the D2D target
interface and supplying the power. Interface specification does not provide special wires for signalling low power modes to the
target device. The CPU should determine when it is time to enter one of the above power modes.The basic flow is as follows:
1.
CPU determines there is no more work pending.
2.
CPU writes a byte to a register on the analog die using blocking write configuring which mode to enter.
3.
Analog die acknowledges that write sending back an acknowledge symbol on the interface.
4.
CPU executes WAIT or STOP command.
5.
Analog die can enter low-power mode - (S12 needs some more cycles to stack data)
; Example shows S12 code
SEI
; disable interrupts during test
; check is there is work pending?
; if yes, branch off and re-enable interrupt
; else
LDAA
#STOP_ENTRY
STAA
MODE_REG
; store to the analog die mode reg (use blocking write here)
CLI
; re-enable right before the STOP instruction
STOP
; stack and turn off all clocks inc. interface clock
For wake-up from STOP the basic flow is as follows:
1.
Analog die detects a wake-up condition e.g. on a switch input or start bit of a LIN message.
2.
Analog die exits Voltage Regulator low-power mode.
3.
Analog die asserts the interrupt signal D2DINT.
4.
CPU starts clock generation.
5.
CPU enters interrupt handler routine.
6.
CPU services interrupt and acknowledges the source on the analog die.
NOTE
Entering STOP mode or WAIT mode with D2DSWAI asserted, the clock will complete the
high duty cycle portion and settle at low level.
ACKERF
CNCLF
TIMEF
TERRF
PARF
ERRIF
D2DEN
D2DERRINT
1