CHAPTER 11: DSTC
506 FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E
In the following sections, "Start Trigger" represents all the above start triggers, SW Start, HW Start and
Chain Start.
Figure 2-1 DES System Method Configuration Diagram
Source address area
Destination address area
DES2
DES3
DES0
DES1
DES5 (option)
DES6 (option)
DES4 (option)
DSTC
Memory
DESTP
DESP
Transfer engine
CPU
7.Write transfer data
5.Read DES
8.Write back DES
9.DES close
6.Read transfer data
4. Assert DREQ[n] signal.
(HW[n] transfer start trigger)
Peripheral device
2. Initialize DES area
1. Write DESTP, HW-DESP[n]
3. Write DESP to SWTR reg.
(SW transfer start trigger)
Read Skip Registers
Control Registers
10.End Report
Operation of the Transfer
The DSTC refers to (5 in Figure 2-1) a DES in DESTP+DESP according to a Start Trigger mentioned
above. The DSTC checks (DES Open Check) details of the DES it refers to, and executes a transfer (6
and 7 in Figure 2-1) if the details have no problem. In addition, if the DES has a Chain Start Trigger, the
DSTC executes a transfer data according to the Chain Start trigger.
The number of transfers to be executed at one Start Trigger varies according to details of a DES and
those of the Chain Trigger. Not all transfers specified in a DES may end at one Start Trigger. If that occurs,
the number of transfers ended and updated transfer addresses are written back to a DES (8 in Figure 2-1).
The DSTC waits for the next Start Trigger, and continues executing the transfer after receiving the next
Start Trigger.
End of the Transfer
The DSTC executes the DES close process (9 in Figure 2-1) after all transfers specified in a DES have
ended. The DES settings can prevent the DES close process from being executed. The DSTC can notify
the CPU of the following events through an interrupt: i. the DSTC is waiting for a Start Trigger; ii. a
transfer has ended normally; iii. a transfer has ended abnormally. (10 in Figure 2-1)
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