2
USB to I2C bridging dongle
Overview
The USB to I2C bridging dongle is the tool that allows interfacing the receiver to the Graphical User Interface
running on a PC. The P2 connector signals are summarized in
. Three LEDs monitor the operation of the
bridge: D1 (green) indicates I2C bus activity, D2 (red) indicates correct initialization of the U1 chip and D3 (yellow)
is a power-on indicator. When the dongle is plugged into the USB port, both D2 and D3 should be on.
Figure 5.
USB-to-I2C bridging dongle top view
Figure 6.
USB-to-I2C bridging dongle schematic
1
1
2
2
3
3
4
4
D
D
C
C
B
B
A
A
Title
Number
Revision
Size
A4
Date:
14.2.2020
Sheet of
File:
C:\Projects\..\STEVAL-ISB68I2C.SchDoc Drawn By:
I2C communication
GND
GND
470nF
C4
GND
1M
R1
100nF
C5
GND
GND GND
MCP_RSTB
MCP_INTB
I/O1
1
GND
2
I/O2
3
I/O2
4
VBUS
5
I/O1
6
U3
USBCL6-2
GP0
1
GP1
2
RST
3
URx
4
U
T
x
5
G
P
2
6
G
P
3
7
S
D
A
8
SCL
9
VUSB
10
D-
11
D+
12
V
S
S
13
N
C
14
N
C
15
V
D
D
16
U1
MCP2221
RST
VBUS
1
D-
2
D+
3
ID
4
GND
5
Shield
Shell
P1
MicroUSB
VBUS
V
D
D
V
D
D
GND
100nF
C1
2.2uF
C3
GND
GND
VBUS
1uF
C2
GND
VDD
VIN
1
INHIBIT
3
NC
4
VOUT
5
G
N
D
2
U2
LD2981
220R
R7
D1
LED
VDD
D2
LED
220R
R6
D3
LED
470R
R5
GND
V
B
U
S
S1
SW-SPST
100nF
C6
R
S
T
GND
G
P
2
G
P
3
G
P
2
G
P
3
S
D
A
SCL
4k7
R2
4k7
R3
V
D
D
V
D
D
S
D
A
S
C
L
1
2
3
4
5
6
P2
Header connector
GND
SDA
SCL
MCP_INTB
RSTB
VBUS
4k7
R4
V
D
D
M
C
P
_I
N
T
B
D4
STPS1L60ZFY
F1
Littelfuse 0603L025
G
S
D
3
2
1
Q1
FDV303N
GND
RSTB
MCP_RSTB
100k
R8
4k7
R9
V
D
D
STEVAL-USBI2C
Table 4.
USB-to-I2C bridging dongle P2 connector
Pin
Signal
Description
1
GND
Common return (ground)
2
SDA
I2C bus, SDA line
3
SCL
I2C bus, SCL line
4
INTB
I/O line dedicated to INT pin management (status reading)
5
RSTB
Reset signal for the STWLC68JRH chip, active low. Not used in the receiver
module.
UM2693
USB to I2C bridging dongle
UM2693
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Rev 1
page 6/18