949
SAM9G45 [DATASHEET]
6438K–ATARM–12-Feb-13
a.
Write the starting source address in the DMAC_SADDRx register for channel x.
b.
Write the starting destination address in the DMAC_DADDRx register for channel x.
c.
Program DMAC_CTRLAx, DMAC_CTRLBx and DMAC_CFGx according to Row 10 as shown in
d.
Write the control information for the DMAC transfer in the DMAC_CTRLAx and DMAC_CTRLBx regis-
ter for channel x. For example, in the register, you can program the following:
– i. Set up the transfer type (memory or non-memory peripheral for source and destination) and flow
control device by programming the FC of the DMAC_CTRLBx register.
– ii. Set up the transfer characteristics, such as:
– Transfer width for the source in the SRC_WIDTH field.
– Transfer width for the destination in the DST_WIDTH field.
– Source AHB master interface layer in the SIF field where source resides.
– Destination AHB master interface layer in the DIF field where destination resides.
– Incrementing/decrementing or fixed address for source in SRC_INCR field.
– Incrementing/decrementing or fixed address for destination in DST_INCR field.
e.
If source picture-in-picture mode is enabled (DMAC_CTRLBx.SPIP is enabled), program the
DMAC_SPIPx register for channel x.
f.
If destination picture-in-picture is enabled (DMAC_CTRLBx.DPIP), program the DMAC_DPIPx regis-
ter for channel x.
g.
Write the channel configuration information into the DMAC_CFGx register for channel x. Ensure that
the reload bits, DMAC_CFGx.SRC_REP, DMAC_CFGx.DST_REP and DMAC_CTRLBx.AUTO are
enabled.
– i. Designate the handshaking interface type (hardware or software) for the source and destination
peripherals. This is not required for memory. This step requires programming the
SRC_H2SEL/DST_h2SEL bits, respectively. Writing a ‘1’ activates the hardware handshaking interface
to handle source/destination requests for the specific channel. Writing a ‘0’ activates the software
handshaking interface to handle source/destination requests.
– ii. If the hardware handshaking interface is activated for the source or destination peripheral, assign
handshaking interface to the source and destination peripheral. This requires programming the
SRC_PER and DST_PER bits, respectively.
3.
After the DMAC selected channel has been programmed, enable the channel by writing a ‘1’ to the
DMAC_CHER.ENABLE[n] bit where is the channel number. Make sure that bit 0 of the DMAC_EN register
is enabled.
4.
Source and destination request single and chunk DMAC transactions to transfer the buffer of data
(assuming non-memory peripherals). The DMAC acknowledges on completion of each chunk/single
transaction and carry out the buffer transfer.
5.
When the buffer transfer has completed, the DMAC reloads the DMAC_SADDRx, DMAC_DADDRx and
DMAC_CTRLAx registers. Hardware sets the buffer Complete interrupt. The DMAC then samples the row
pleted. Hardware sets the transfer complete interrupt and disables the channel. So you can either respond
to the Buffer Complete or Chained buffer transfer Complete interrupts, or poll for the Channel Enable in
the Channel Status Register (DMAC_CHSR.ENABLE[n]) until it is disabled, to detect when the transfer is
complete. If the DMAC is not in Row 1, the next step is performed.
6.
The DMAC transfer proceeds as follows:
a.
If interrupts is un-masked (DMAC_EBCIMR.BTC[x] = ‘1’, where x is the channel number) hardware
sets the buffer complete interrupt when the buffer transfer has completed. It then stalls until the
STALLED[n] bit of DMAC_CHSR register is cleared by software, writing ‘1’ to
DMAC_CHER.KEEPON[n] bit where n is the channel number. If the next buffer is to be the last buffer