AT32F435/437
Series Reference Manual
2022.11.11
Page 510
Rev 2.03
Table 24-11
NOR/PSRAM param eter registers
Parameter
register
Function
Access mode
Unit
ADDRST
Address set-up time
1, 2, A, B, C, D and multiplexed
HCLK cycle
ADDRHT
Address-hold time
D and multiplexed
HCLK cycle
DTST
Data set-up time
1, 2, A, B, C, D and multiplexed
HCLK cycle
DTLAT
Data latency time
Synchronous
XMC_CLK cycle
CLKPSC
Clock prescaler
Synchronous
HCLK cycle
In addition to timing parameter registers for timing control, if the wait enable bit (NWASEN or NWSEN)
is enabled, the XMC will start to check whether the XMC_NWAIT signal is in wait request state during
data set time. If so, the XMC will wait until the XMC_NWAIT returns to the ready state before data transfer.
24.4.2.1 Read/write operation with the same timings
The timing of read and write operation in mode 1 and mode 2 is based on the XMC_BK1TMG register
configuration.
Mode 1
As configured in Table 24-12
and Table 24-13, the XMC uses mode 1 to access the external memory.
The timing of read operation is shown in Figure 24-3. The timing of write operation is shown in
Table 24-12
Mode 1— SRAM/NOR Flash chip select control register (XMC_BK1CTRL) configuration
Bit
Description
Configuration
Bit 31: 20
Reserved
0x0
Bit 19
MWMC: Memory write mode control
0x0
Bit 18: 16
CRPGS: CRAM page size
0x0
Bit 15
NWASEN:
NWAIT in asynchronous
transfer enable
Configure according to memory specifications
Bit 14
RWTD: Read-write timing different
0x0
Bit 13
NWSEN: NWAIT in synchronous
transfer enable
0x0
Bit 12
WEN: Write enable
Configure according to needs
Bit 11
NWTCFG: NWAIT timing configuration 0x0
Bit 10
WRAPEN: Wrapped enable
0x0
Bit 9
NWPOL: NWAIT polarity
Configure according to memory specifications
Bit 8
SYNCBEN: Synchronous burst enable 0x0
Bit 7
Reserved
0x1
Bit 6
NOREN: NOR
flash access enable
0x0
Bit 5: 4
EXTMDBW: External memory data
bus width
Configure according to memory specifications
Bit 3: 2
DEV: Memory device type
Configure according to memory specifications. It is valid
except 0x2 (NOR Flash)
Bit 1
ADMUXEN: Address/data multiplexing
enable
0x0
Bit 0
EN: Memory bank enable
0x1
Table 24-13
Mode 1— SRAM/NOR Flash chip select timing register (XMC_ BK1TMG) configuration
Bit
Description
Configuration
Bit 31: 30
Reserved
0x0
Bit 29: 28
ASYNCM: Asynchronous mode
0x0
Bit 27: 24
DTLAT: Data latency
0x0
Bit 23: 20
CLKPSC: Clock prescale
0x0
Bit 19: 16
BUSLAT: Bus latency
Indicates the time the XMC_NE[x] from the rising edge to the
falling edge. Configure according to needs and memory
specifications
Bit 15: 8
DTST: Data setup time
and
. Configure according to
needs and memory specifications.
Bit 7: 4
ADDRHT: Address-hold time
0x0
Bit 3: 0
ADDRST: Address setup time
and
. Configure according to
needs and memory specifications.