13 DMA CONTROLLER (DMAC)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
13-9
(6) According to the control information, the DMAC increments the source and/or destination addresses. The ad-
dresses are not changed if “address fixed” is specified. Also the transfer counter is decremented.
(7) The DMAC writes the modified control information back to the control table.
(8) The DMAC checks the transfer counter. If the value of the counter is not 0, the process is terminated here. Step (9)
is not executed. Step (9) is executed if the transfer counter has reached 0.
(9) The DMAC sets the end-of-transfer flag (ENDF
x
/DMAC_END_FLG register) and clears the transfer status
flag (RUN
x
). If DMAIE
x
/DMAC_IE register is set to 1 (end-of-transfer interrupt enabled), the DMAC outputs
an interrupt request to the ITC.
This completes the single transfer process.
Successive Transfer Mode
13.5.2
The channels for which TM (D2/1st word) in control information is set to 1 operate in the successive transfer mode.
In this mode, a data transfer is performed by one trigger a number of times as set by the transfer counter.
The operation in the successive transfer mode is shown by the flow chart in Figure 13.5.2.1.
START
END
Load control information
Clear trigger or pause flags
to accept next trigger
Transfer data
(8 bits, 16 bits, or 32 bits)
Increment address
Transfer counter - 1
Store control information
Set pause flag
Read source data pointer
(8 bits or 16 bits)
ST = 1?
No (data)
Yes (pointer)
SRINC/DSINC[1:0]
0x0 (address fixed)
0x1 (address increment)
Transfer counter = 0?
Yes
No
High-priority DMA request
Occurred
CHEN = 1?
No (channel disabled)
Not occurred
Yes (channel enabled)
Store control information
DMAC interrupt request
5.2.1 Operation Flow in Successive Transfer Mode
Figure 13.