Jameco Electronics 3000 Manual De Usuario

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Rabbit 3000 Microprocessor
Figure 12-8 shows the timing relationship among 
perclk
, the external serial clock, and 
data receive. Note that RxA is sampled by the rising edge of 
perclk
.
Figure 12-8.  Synchronous Serial Data Receive Timing with External Clock (Mode 00)
When clocking the Rabbit externally, the maximum serial clock frequency is limited by 
the amount of time required to synchronize the external clock with the Rabbit 
perclk
.  If 
we sum the maximum number of 
perclk
 cycles required to perform clock synchroniza-
tion for each of the receive and transmit cases, then the fastest external serial clock fre-
quency would be limited to 
perclk
/6.
Valid
perclk
CLKA 
RxA
(Ext.)