Samsung SC32442B54, User Manual

Page: 246 / 647

DMA SC32442B RISC MICROPROCESSOR
8-10
DCONn Bit Description Initial State
SERVMODE [27] Select the service mode between Single service mode and Whole
service mode.
0: Single service mode is selected in which after each atomic transfer
(single or burst of length four) DMA stops and waits for another DMA
request.
1: Whole service mode is selected in which one request gets atomic
transfers to be repeated until the transfer count reaches to 0. In this
mode, additional request are not required.
Note that even in the Whole service mode, DMA releases the bus
after each atomic transfer and then tries to re-get the bus to prevent
starving of other bus masters.
0
HWSRCSEL [26:24] Select DMA request source for each DMA.
DCON0: 000:nXDREQ0 001:UART0 010:SDI 011:Timer 100:USB device EP1
DCON1: 000:nXDREQ1 001:UART1 010:I2SSDI 011:SPI 100:USB device EP2
DCON2: 000:I2SSDO 001:I2SSDI 010:SDI 011:Timer 100:USB device EP3
DCON3: 000:UART2 001:SDI 010:SPI 011:Timer 100:USB device EP4
These bits control the 4-1 MUX to select the DMA request source of
each DMA. These bits have meanings only if H/W request mode is
selected by DCONn[23].
00
SWHW_SEL [23] Select the DMA source between software (S/W request mode) and
hardware (H/W request mode).
0: S/W request mode is selected and DMA is triggered by setting
SW_TRIG bit of DMASKTRIG control register.
1: DMA source selected by bit[26:24] triggers the DMA operation.
0
RELOAD [22] Set the reload on/off option.
0: auto reload is performed when a current value of transfer count
becomes 0 (i.e. all the required transfers are performed).
1: DMA channel (DMA REQ) is turned off when a current value of
transfer count becomes 0. The channel on/off bit (DMASKTRIGn[1])
is set to 0 (DREQ off) to prevent unintended further start of new
DMA operation.
0
DSZ [21:20] Data size to be transferred.
00 = Byte 01 = Half word
10 = Word 11 = reserved
00
TC [19:0] Initial transfer count (or transfer beat).
Note that the actual number of bytes that are transferred is computed
by the following equation: DSZ x TSZ x TC. Where, DSZ, TSZ (1 or 4),
and TC represent data size DCONn[21:20], transfer size DCONn[28],
and initial transfer count, respectively. This value will be loaded into
CURR_TC only if the CURR_TC is 0 and the DMA ACK is 1.
00000