COM20051I Datasheet, PDF (65/74 Pages) SMSC Corporation – Integrated Microcontroller and ARCNET (ANSI 878.1) Interface

USING THE COM20051I'S EMULATION MODE
The COM20051I is unique among special purpose 8051 based devices in that it can be used in conjunction with a
standard 16MHz 80C32 ICE. The COM20051I incorporates an Emulate mode that puts the internal microcontroller in
a high impedance state so an external processor (like an ICE) can access the internal ARCNET core through the
COM20051I's pins. The ICE should be connected in parallel to the COM20051I as shown in Figure 24. The ICE
should operate off of its internal oscillator.
C2
33pf
C3
33pf
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
Y1
16Mhz
EMULATOR POD
U3
31
EA/VP
19 _X1
18 _X2
9 _RESET
12
13 ^INT0
14 ^INT1
15
T0
T1
1
2
P1.0/T2
3
4
5
6
7
8
P1.1/T2x
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
8032
39
P0.0
P0.1
P0.2
P0.3
38
37
36
35
P0.4
P0.5
P0.6
P0.7
34
33
32
P2.0
P2.1
21
22
23
P2.2 ₂₄
P2.3 ₂₅
P2.4
P2.5
P2.6
P2.7
26
27
28
RD
WR
PSEN
ALE/P
TXD
RXD
17
16
29
30
11
10
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
A8
A9
A10
A11
A12
A13
A14
A15
C23 33pf
Y3
R19
1.5K
C22
33pf
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
SMSC COM20051I
U1
35 _EA/VP
21 _X1
20 _X2
10 _RESET
14
15
INT0
16
17
INT1
T0
T1
2
3
4
P1.0
P1.1
5
6
P1.2
P1.3
7
8
9
P1.4
P1.5
P1.6
P1.7
P0.0
P0.1
P0.2
43
42
41
40
AD0
AD1
AD2
AD3
P0.3 ₃₉
AD4
P0.4 ₃₈
AD5
P0.5
P0.6
P0.7
37
36
AD6
AD7
P2.0
P2.1
P2.2
24
25
26
27
P2.3
P2.4
P2.5
P2.6
28
29
30
31
P2.7
19
RD
WR
18
32
PSEN
ALE/P
TXD
RXD
33
13
11
12
PULSE1
PULSE2
RXIN
TXEN
23
1
34
COM20051I
A8
A9
A10
A11
A12
A13
A14
A15
C0
C1
C2
C3
C4
C5
FIGURE 23 – CONNECTIONS FOR EMULATION MODE
SMSC DS – COM20051I
Page 65
Rev. 03/27/2000