NuMicro® NUC029LEE/NUC029SEE
32-bit Arm
®
Cortex
®
-M0 Microcontroller
Aug, 2018
Page
170
of
497
Rev 1.00
N
U
MICRO
®
N
UC02
9L
E
E
/N
UC029
S
E
E
T
E
CHN
ICA
L R
E
F
E
R
E
NC
E
M
A
NU
A
L
Insert Idle Cycle
When EBI is accessing continuously, bus conflict may occur if the device access time is much
longer compared with system clock frequency. The EBI controller supplies additional idle cycle to
solve this problem. During idle cycle period, all control signals of EBI bus are inactive. The
following figure shows idle cycle.
nCS
AD[15:0]
MCLK
nRD
tACC
tASU
tAHD
nWR
AD[15:0]
ALE
tALE
tLHD tA2D
Address
output[15:0]
WData output[15:0]
RData
input
Idle cycle
XX
tASU
tALE
Address
output[15:0]
Address
output[15:0]
Address
output[15:0]
Figure 6.5-6 Timing Control Waveform for Insert Idle Cycle
There are two conditions that EBI can insert idle cycle by timing control:
1.
After write access
2.
After read access and before the next read access
By setting ExtIW2X[3:0] of EXTIME [15:12] and ExtIR2R[3:0] of the register EXTIME[27:24], the
time of idle cycle can be specified from 0~15 MCLK.