677
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
32.8.7
Using the Peripheral DMA Controller (PDC)
The use of the PDC significantly reduces the CPU load.
To assure correct implementation, respect the following programming sequences:
32.8.7.1
Data Transmit with the PDC
1.
Initialize the transmit PDC (memory pointers, size, etc.).
2.
Configure the master mode (DADR, CKDIV, etc.).
3.
Start the transfer by setting the PDC TXTEN bit.
4.
Wait for the PDC end TX flag.
5.
Disable the PDC by setting the PDC TXDIS bit.
32.8.7.2
Data Receive with the PDC
1.
Initialize the receive PDC (memory pointers, size - 1, etc.).
2.
Configure the master mode (DADR, CKDIV, etc.).
3.
Start the transfer by setting the PDC RXTEN bit.
4.
Wait for the PDC end RX flag.
5.
Disable the PDC by setting the PDC RXDIS bit.
32.8.8
SMBUS Quick Command (Master Mode Only)
The TWI interface can perform a Quick Command:
1.
Configure the master mode (DADR, CKDIV, etc.).
2.
Write the MREAD bit in the TWI_MMR register at the value of the one-bit command to
be sent.
3.
Start the transfer by setting the QUICK bit in the TWI_CR.
Figure 32-14. SMBUS Quick Command
TXCOMP
TXRDY
Write QUICK command in TWI_CR
TWD
A
S
DADR
R/W
P
Summary of Contents for SAM4S Series
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