UCS1003-1 Evaluation Board User’s Guide
DS50002510A-page 24
2016 Microchip Technology Inc.
3.3
MCP2221 USB-TO-SMBUS BRIDGE
The MCP2221 is a USB-to-UART/I
2
C bridge that supports SMBus communication. It is
controlled through USB interface by the GUI running on the PC. It is the master device
on the SMBus/I
2
C bus. It is used to read and write the registers of the two devices
connected to the SMBus/I
2
C interface: UCS1003-1 and MCP23018 I/O expander.
3.4
MCP23018 I/O EXPANDER
MCP23018 is a 16-bit I/O Expander with open-drain outputs and I
2
C interface. Its I
2
C
address is configured to
0100_000(R/W)
, different than all possible addresses of the
UCS1003-1.
The I/O pins used in this application are configured as inputs. They are used to read
the logic state of the following UCS1003-1 pins: ALERT#, ADET#, PWR_EN, EM_EN,
M1, M2.
3.5
DIRECT SMBUS CONNECT OPTION
It is also possible to connect an external SMBus master to the UCS1003-1 Evaluation
Board. Remove the jumpers on J7 and connect the SMBus master to the header pins
that are linked directly to UCS1003-1 pins SMDATA/LATCH and SMCLK/S0. Note that
ground must be connected to one of the test point grounds or header pins on the
evaluation board. See
Figure 3-1
for header pins description.
FIGURE 3-1:
UCS1003-1-to-SMBus Bridge Jumpers.
USB bridge
SDA pin
SMDATA/LATCH
UCS1003-1
pin
USB bridge
SCL pin
SMDATA/LATCH
UCS1003-1
pin
Ground
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