אפיקים טוריים בין רכיבים
✦ בנוי על ידי פהד גאנם ✦
العربية
☀ מצב בהיר
3
▾
✕
C
cable
= L · c | τ = R
out
· C
cable
| t
bit
=
1
baud
| L
max
=
C
max
c
9600 baud
A · 65
±9 V
10 m
100 pF/m
300 Ω
C = 25 · 100 = 2500 pF
τ = 300 · 2500·10
−12
= 0.75 µs
t
bit
=
1
19200
= 52.08 µs
52.08
0.75
= 69.4
L
max
=
2500
100
= 25 m
4
▾
✕
t
bit
=
1
f
SCL
| N = 1 + 7 + 1 + 1 + 8 + 1 + 1 | addr
8
= (addr
7
<< 1) | R/W̄ | t
rise
≈ 0.85 · R
p
· C
bus
0x20
0xA5
100 kHz
4.7 kΩ
100 pF
(0x20 << 1) | 0 = 0x40 · (0x20 << 1) | 1 = 0x41
N = 7 + 1 + 1 + 8 + 1 = 18
t = 18 ·
1
100000
= 180 µs
t
r
≈ 0.85 · 4700 · 200·10
−12
= 0.80 µs
10
2
= 5 µs ≫ 0.80 µs
4.2
▾
✕
addr = 0x20 + (A2·4 + A1·2 + A0) | P
n
=
byte
2
n
mod 2 | N
pins
= 8 · 8 = 64
0xF0
A2
A1
A0
7
6
5
4
3
2
1
0
0x20, 0x21, 0x22, 0x23
0b10101010 = 0xAA
1 << 2 = 0b00000100 = 0x04
0xAA | 0x04 = 0b10101010 | 0b00000100 = 0b10101110 = 0xAE
0xAA ⊕ 0xAE = 0x04
4.3
▾
✕
BCD → dec:
b
16
· 10 + (b mod 16) | dec → BCD:
d
10
· 16 + (d mod 10) | addr = 0x68
14
45
0x45
0x45 = 69 · 0x14 = 20
min =
0x45
16
· 10 + (0x45 mod 16) = 4 · 10 + 5 = 45
hr = 1 · 10 + 4 = 14
45 →
45
10
· 16 + (45 mod 10) = 64 + 5 = 0x45
0x80 = 0b10000000 → CH = 1, sec = 0
5
▾
✕
t
byte
=
8
f
SCLK
| mode = 2·CPOL + CPHA | N
wires
= 3 + n
SS
| MISO ⊕ MOSI:
1
1
exchange
0xA3
0x5C
1 MHz
MODE 0
MODE 1
MODE 2
MODE 3
3
t
byte
=
8
8·10
6
= 1 µs
n =
1
1·10
−6
= 10
6
master: 0x5C · slave: 0xA3
SPI.transfer(0xFF) → rx
3 + 5 = 8 · 3 + 1 = 4
5.2
▾
✕
frame = addr
8
‖ data
8
| latch ↑SS | f
mux
=
f
disp
scan + 1
| N
bytes
= 2 · n
chips
0x01
0x3C
0x08
7
t =
16
4·10
6
= 4 µs
t = 8 · 4 = 32 µs
0x0F,0x00 · 0x09,0x00 · 0x0B,0x07 · 0x0C,0x01
0x0A, 0x08
N = 2 · 4 = 8 → t =
64
4·10
6
= 16 µs
5.3
▾
✕
N
bytes
=
W · H
8
| fps =
f
SCLK
8 · N
bytes
| page =
y
8
| V
x
= V
cc
·
x
W
20
11
128
8 MHz
0.60
0.35
N =
128 · 64
8
= 1024
t =
8 · 1024
8·10
6
= 1.024 ms → fps = 977
page =
11
8
= 1 · bit = 11 mod 8 = 3
buf[1][20] |= (1 << 3)
x =
614
1023
· 128 = 76.8 → 76
→
🏠
♿