Freescale SMeCm33ic59o3nductor, Inc.
STATE MACHINE WITH STROBE OSCILLATOR CONTROL
Figure 15 details the state machine when the strobe oscillator is enabled (SOE=1).
Figure 15: State machine with strobe oscillator control
State 2
Sleep mode
Reset and Start Strobe Counter
SPI master
Strobe Counter=SR
Strobe Counter ≠ SR
OR STROBE=1 AND STROBE pin released
State 3
Run mode
Waiting for ID word
ID detected
AND HE=1
ID detected
AND HE=0
Time-out
State 4
Run mode
Reset and start Timer
Waiting for Header
Header received
State 5
Run mode
Output data & clock
Waiting for End of Message
EOM received
State 2:
The circuit is in Sleep mode, except for the Strobe oscillator and the Strobe counter.
State 3:
The circuit is waiting for a valid ID word. If ID or its complement is detected, the state machine advances to state
4. If not, it will go back into sleep mode (state 2) at the end of the Strobe period.
State 4:
ID or its complement has been detected, Data Manager is waiting for Header or its complement. Time-out
counter is running. This counter will count up to 66 (± 1) times the strobe oscillator period (TStrobe).
State 5:
If Header has been received, data and clock signals are output on the SPI port until End of Message indicates the
data sequence end. If the complement of Header has been received, output data are complemented too.
For all states:
At any time, a low level applied on RESETB during more than one Ts forces the state machine to state 1. When
the transition condition from one state to the next one is fulfilled, the transition time is one Ts (except for reaching
state 2). The transition time to state 2 is 2 × Ts (+ duration of the dummy byte if it is shifted out, only for transition
coming from state 5).
© Motorola, Inc., 2002.
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revision 7.0, 5 February 2002