TMP92CZ26A
92CZ26A-103
Sample2) Calculation examples for CPU
+
LDMA
Conditions 1:
CPU operation speed (f
SYS
)
: 60 MHz
Display RAM
: Internal RAM
Display size
: QVGA (320seg
×
240com)
Display quality
: 65536 colors (TFT)
Refresh rate
: 70 Hz (including 20 clocks of dummy cycles)
Calculation example 1:
t
STOP
(LDMA)
= ((SegNum
×
K / 8)
×
t
LRD
)
+
(1 / f
SYS
[Hz])
=
((320
×
16 / 8)
×
1 / f
SYS
[Hz] / 4)
+
(1 / f
SYS
[Hz])
=
((640)
×
16.67 [ns] / 4)
+
16.67 [ns]
= 2.68 [
μ
s]
LHSYNC [period: s] = 1/70 [Hz] /(COM+20=260) = 54.95 [
μ
s]
CPU bus stop rate
= t
STOP
(LCD)[s] / LHSYNC
[period: s]
= 2.68 [
μ
s] / 54.95 [
μ
s] = 4.88 [%]
Conditions 2:
CPU operation speed (f
SYS
)
: 10 MHz
Display RAM
: 16-bit external SRAM (0 waits)
Display size
: QVGA (240seg
×
320com)
Display quality
: 4096 colors (STN)
Refresh rate
: 100 Hz (0 dummy cycles)
Calculation example 2:
t
STOP
(LDMA)
= (SegNum
×
K / 8)
×
tLRD
=
(240
×
12 / 8)
×
( 2
+
wait count) / f
SYS
[Hz] / 2
=
(360)
×
200 [ns] / 2
= 36 [
μ
s]
LHSYNC [period: s]
= 1/100 [Hz] / (COM = 240) = 41.67 [
μ
s]
CPU bus stop rate
= t
STOP
(LCD)[s] / LHSYNC
[period: s]
= 36 [
μ
s] / 41.67 [
μ
s] = 86.40 [%]