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AT32F435/437
Series Reference Manual
2022.11.11
Page 509
Rev 2.03
Table 24-9
Address translation between HADDR and external m em ory
External memory data
width
Address connection
Accessible maximum memory
space (bits)
8-bit
HADDR[25: 0] is linked to XMC_A[25: 0].
In multiplexed and synchronous mode,
HADDR[15: 0] is connected to XMC_D[15: 0]
during address latch period.
64 Mbyte x8 =512 Mbit
16-bit
HADDR[26: 1] is connected to XMC_A[25: 0].
In multiplexed and synchronous mode,
HADDR[16: 1] is connected to XMC_D[15: 0]
during address latch period
(64 Mbyte x 16)/2=512 Mbit
Data access
In case that the AHB data width is not equal to that of the memories, the XMC will make appropriate
arrangement according to the typical signals of the external memories. Table 22-6 lists the operation
modes supported by XMC.
Table 24-10
Data access width vs. external mem ory data width
Memory
Mode
AHB data width
Memory width
Description
SRAM
Asynchronous
read/write
8/16/32
8
One-time access, or split into 2
or 4 accesses
Asynchronous
read/write
8/16/32
16
XMC_LB and XMC_UB, One-
time, or split into two access
NOR Flash
Asynchronous
read
8
16
Asynchronous
read/write
16
16
Asynchronous
read/write
32
16
Split into 2 XMC accesses
Synchronous
read
16
16
Synchronous
read
32
16
Split into 2 XMC accesses
PSRAM
Asynchronous
read
8
16
Asynchronous
write
8
16
Use XMC_LB and XMC_UB
Asynchronous
read/write
16
16
Asynchronous
read/write
32
16
Split into 2 XMC accesses
Synchronous
write
8
16
Use XMC_LB and XMC_UB
Synchronous
read/write
16
16
Synchronous
read/write
32
16
Split into 2 XMC accesses
24.4.2 Access mode
The XMC offers various access modes. Each access mode is operated based on the timing parameters,
as shown in Table 24-11.Users can perform programming operations according to the specifications of
the external memory and application needs.
Access modes available in the XMC:
Read/write operation with the same timings: Mode 1 and Mode 2
Read/write operation with different timings: Mode A, B, C and D
Multiplexed address data lines
Clock-based synchronous mode