II BUS MODULES: HIGH-SPEED DMA (HSDMA)
II-1-22
EPSON
S1C33E07 TECHNICAL MANUAL
1: The data bus is placed in high-impedance state during reading from the I/O device. Furthermore, the exter-
nal memory read/write address is delivered from the memory address registers in the control information
SxADRL and SxADRH.
SxADRL: Ch.x Source Address[15:0] in the HSDMA Ch.x Low-Order Source Address Setup Register
(STD mode: D[15:0]/0x301124 + 0x10x, ADV mode: D[15:0]/0x301164 + 0x10x)
SxADRH: Ch.x Source Address (high-order bits) in the HSDMA Ch.x High-Order Source Address Setup
Register (STD mode: D[11:0]/0x301126 + 0x10x, ADV mode: D[15:0]/0x301166 + 0x10x)
2: In standard mode, SxID (D4/0x301162 + 0x10x) is fixed at 0.
Successive transfer mode (single-address mode)
The channel for which DxMOD[1:0] (D[15:14]/0x30112A + 0x10x) in control information is set to 01 oper-
ates in 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 transfer counter is decremented to 0 by one transfer executed.
The operation of HSDMA in successive transfer mode is shown by the flow chart in Figure II.1.6.2.2.
START
END
Transfer counter - 1
Transfer
counter = 0
N
Y
Increments/decrements
address
: according to SxIN or
SxID settings
Data read from source and
data write to destination
(1 byte, 1 half word or 1 word)
Clear trigger flag HSx_TF
to accept next trigger
Clear HSDMA enable bit
HSx_EN
Set cause-of-interrupt flag
FHDMx
Restores initial values to
address
: according to SxIN or
SxID settings
Figure II.1.6.2.2 Operation Flow in Successive Transfer Mode
(1) When a trigger is accepted, the trigger flag HSx_TF (D0/0x30112E + 0x10x) is cleared. Data of the size
set in the control information is read from the external memory or I/O device according to the specified di-
rection and is written to the I/O device or external memory.
1
(2) The addresses are incremented or decremented according to the SxIN[1:0] (D[13:12]/0x301126 + 0x10x)
or SxID (D4/0x301162 + 0x10x) settings.
2
(3) The transfer counter is decremented.
(4) Steps (1) to (3) are repeated until the transfer counter reaches 0.
(5) The address returns to the initial value if SxIN[1:0] (D[13:12]/0x301126 + 0x10x) is 10 or SxID (D4/
0x301162 + 0x10x) is 1.
2
(6) The HSDMA enable bit HSx_EN (D0/0x30112C + 0x10x) is cleared and HSDMA cause-of-interrupt flag
in ITC is set when the transfer counter reaches 0.
1: The data bus is placed in high-impedance state during reading from the I/O device. Furthermore, the exter-
nal memory read/write address is delivered from the memory address registers in the control information
SxADRL and SxADRH.
2: In standard mode, SxID (D4/0x301162 + 0x10x) is fixed at 0.