Digi NS9215, Hardware Reference Manual, Page: 500 / 517

T I M I N G
Memory Timing
500
Hardware Reference NS9215
Static write cycle
with configurable
wait states
WTWR = from 0 to 15
WWEN = from 0 to 15
The WTWR field determines the length on the write cycle.
During a 32-bit transfer, all four byte_lane signals will go low.
During a 16-bit transfer, two byte_lane signals will go low.
During an 8-bit transfer, only one byte_lane signal will go low.
Notes:
1 Timing of the st_cs_n signal is determined with a combination of the WTWR and WWEN fields. The
st_cs_n signal will always go low at least one clock before we_n goes low, and will go high one clock
after we_n goes high.
2 Timing of the we_n signal is determined with a combination of the WTWR and WWEN fields.
3 Timing of the byte_lane signals is determined with a combination of the WTWR and WWEN fields. The
byte_lane signals will always go low one clock before we_n goes low, and will go one clock high after we_n goes
high.
4 If the PB field is set to 0, the byte_lane signals will function as the write enable signals and the we_n signal will
always be high.
5 If the PB field is set to 0, the timing for the byte_lane signals is set with the WTWR and WWEN fields.
M 22 M 21
M 24 M 2 3
M 22 M 21
M 20 M 1 9
M 18 M 1 7
M 16 M 1 5
N ote -2
N ote -3
N ote -5 N ot e- 4
N ote - 1
c lk _ ou t
d ata < 31: 0>
ad dr < 17: 0>
s t_c s _ n< 3: 0>
we _n
by te _l an e< 3: 0>
by te _l an e[ 3:0 ] a s W E *