CHAPTER 11: DSTC
552 FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E
4.6 Examples of Controlling DSTC
This section explains sample procedures for controlling the DSTC.
Sample Procedures for Transition to Standby State and for Transition to Normal State
The DSTC transits to the standby state upon a bus reset. To make the DSTC execute a transfer, it is
necessary to make the DSTC first transit from the standby state to the normal state. In the case of not
making the DSTC execute a transfer, the power consumption of the system can be reduced by keeping
the DSTC in the standby state.
Figure 4-6 shows a sample procedure for making the DSTC transit from the standby state to the normal
state and another sample procedure for making the DSTC transit from the normal state to the standby
state. Numbers in the figure correspond to those used in the explanation after the figure.
Figure 4-6 Examples of Transition to Standby State and Transition to Normal State
#1 Start
(DSTC standby state)
#2 Write "0x04" to CMD register.
#3 Read CMD register. #8 Read CMD register.
#7 Write "0x08" to CMD register.
#6 Start
(DSTC normal state)
#10 End
#9 CMD == 0x01#4 CMD == 0x00
N
Y
Y
N
#5 End
#1 to #5 show the procedure for making the DSTC transit from the standby state to the normal state.
Issue a standby release command (write 0x04 to the CMD Register). If the DSTC transits to the normal
state, the CMD Register reads 0x00. Check that the CMD Register reads 0x00.
#6 to #10 show the procedure for making the DSTC transit from the normal state to the standby state.
Issue a standby transition command (write 0x08 to the CMD Register). If the DSTC transits to the standby
state, the CMD Register reads 0x01. Check that the CMD Register reads 0x01.
While the DSTC is executing a transfer, if a standby transition command is issued, the transfer in
progress is compulsorily ended and a DES close process for that transfer is executed. After the DES
close process has been completed, the DSTC transits to the standby state.
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