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AT32F435/437
Series Reference Manual
2022.11.11
Page 663
Rev 2.03
28.3.3 DMA handshake mode
The DMA mode can also be used to access data ports. The DMA controller register must be
programmed as DMA handshake mode. In this mode, the host controller sends a DMA request when
the receive/transmit FIFO threshold is reached. The threshold values are in terms of words. The DMA
request is still sent when the last data transfer is less than the threshold.
Figure 28-2 DMA handshake mode
dma_req
dma_ack
28.3.4 XIP port (direct address mapping read/write)
The ATQSPI020 offers a XIP slave port (direct address mapping read/write) for users to perform a direct
access to system addresses. In this case, only 0x10 register can be used to select a command slave
port or a XIP port, or read other registers than data register (0x100). It should be noted that when reading
Flash memory using this XIP port, the Abort function (bit [8] in the 0x10 register) cannot be used
(meaning that the bit [20] of the 0x10 register is set to 1), and the XIP port cannot be aborted with this
bit, which means that port switch must be performed in sequence. The user’s system must have a main
Flash memory, in which the user can load the port switch code and perform switching operation.
28.3.5 XIP port prefetch
The XPI port supports read prefetch with 2-channel read cache.
28.3.6 SPI device operation
Serial mode
The host controller supports a SPI protocol (mode 0 and mode 3). The command queue register must
be programmed according to SPI device specification. Refer to Figure 28-3 and Figure 28-10 for more
information on how to program a command queue.
To execute a write enable command, set instruction code to 06h, write enable, and set instruction length
to 1. Refer to Figure 28-3 for details.
Figure 28-3 Write enable
High Impedance
CS
CLK
DI
DO
Instruction (06h)
0
1
2
3
4
5
6
7
Mode3 (SCK idle high)
Mode3
Mode0
Mode0 (SCK idle low)
Data capture
To execute page programming command, set instruction code to 02h, address register, address size,
write enable and set instruction length to 1.