Table 1-3. EZ-USB Series 2100 Pinouts by Pin Function
2125S
2126S
2135S
2136S
2121S
2131Q 2122S
2131S
2122T 2126T
Name
Type Default
Description
40
20
20
22
23
22
23
PC6 or WR#
I/O
I/O
I
Multiplexed pin whose function is selected by the
(PC6) WR bit of the PORTCCFG register. If WR=0, the pin
is the bi-directional I/O port bit PC6. If WR=1, the
pin is the active-low write signal for external mem-
ory. If the WR# signal is used, it should be externally
pulled up to Vcc to ensure that the write strobe is
inactive at power-on.
41
21
21
PC7 or RD#
I
Multiplexed pin whose function is selected by the RD
(PC7) bit of the PORTCCFG register. If RD#=0, the pin is
the bi-directional I/O port bit PC7. If RD#=1, the pin
is the active-low read signal for external memory. If
the RD# signal is used, it should be externally pulled
up to Vcc to ensure that the read strobe is inactive at
power-on.
4
2
2
2
2
CLK24
Output
24-MHz clock, phase locked to the 12-MHz input
clock. It operates at 12 MHz in 12-MHz mode (48-pin
package). Output is disabled by setting the
OUTCLKEN bit = 0 in the CPUCS register.
66
37
37
40
40
WAKEUP# Input
N/A USB Wakeup. If the 8051 is in suspend, a high to
low edge on this pin starts up the oscillator and inter-
rupts the 8051 to allow it to exit the suspend mode.
Holding WAKEUP# LOW inhibits the EZ-USB chip
from entering the suspend state.
2
65
64
36
35
36
35
39
38
39
38
SCL
SDA
OD
OD
Z
I CClock. Pull up to Vcc with a 2.2K-ohm resistor,
2
even if no I C device is connected.
2
Z
I C Data. Connect to Vcc with a 2.2K-ohm resistor
2
even if no I C device is connected.
2, 22, 11,22, 11, 22, 12,24, 12,24,
42, 62 33, 44 33, 44 36, 48 36, 48
Vcc
N/A Vcc. 3.3V power source.
3, 5, 6, 1, 3, 4, 1, 3, 4, 1, 3, 4, 1, 3, 4,
GND
N/A Ground. Note: On the 80-pin package, pins 5, 6, 13,
14, and 72 are test pins that must be grounded for
normal operation. Driving pin 72 high floats all func-
tional pins for automated board test.
13,14, 5, 6,
5, 6,
5, 6,
5, 6,
17,23, 12,23, 12,23, 13,25, 13,25,
43,56, 34, 38 34, 38 37, 41 37, 41
63,72,
78
The corresponding pins on the 44-pin package are
pins 3, 4, 5, 6, and 38. Driving pin 38 high floats all
functional pins for automated board test.
The corresponding pins on the 48-pin package are
pins 3, 4, 5, 6, and 41. Driving pin 41 high floats all
functional pins for automated board testing.
N/A
67
N/A
N/A
N/A
N/A
15
15
CPU12MHZ
NC
N/A This input controls the speed of the 8051:
- Tied High - 12 MHz
- Tied Low - 24 MHz
N/A
N/A
N/A This pin must be left unconnected.
Page 1-28
Chapter 1. Introducing EZ-USB
EZ-USB TRM v1.9
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