MCP2221 I
2
C DEMONSTRATION
BOARD USER’S GUIDE
2016 Microchip Technology Inc. DS50002480A-page 43
Chapter 5. Troubleshooting
This chapter handles a number of possible scenarios that may occur when the
MCP2221 I
2
C Demonstration Board does not function as expected.
5.1 BOARD NOT DETECTED BY PC
In case the PC does not signal, either visually or acoustically, that the MCP2221 board
has been connected, perform the following actions:
• Check the board’s power selection jumper. Make sure jumper J19 is connected
and that its default position is for 5V operation.
• Connect the PC to the correct on-board mini-USB socket. The board communi-
cates with the PC and it is also powered using the mini-USB connector marked
with J4, not J21.
• Verify that enough power is provided to the board. If the board connects through a
USB hub, then the hub should be self-powered.
5.2 USB DRIVER INSTALLATION ISSUES
When connecting the MCP2221 board to a PC running a Windows
®
operating system,
the USB driver should install automatically. In case the process is not successful, the
driver can be downloaded from http://www.microchip.com/mcp2221, extracted to a
folder on the local drive and then installed manually, as described below.
1. From the Start menu, select Control Panel>Device Manager
. Connect the board
to the PC and see what device is added to the list under Ports.
2. Right-click on the device and click the Update Driver Software… button.
3. Manually select the folder where the driver has been extracted.
4. Click OK.
After the driver installs, a system restart may be required.
5.3 PC APPLICATION REPORTS “MCP2221 NOT CONNECTED”
When a USB device (such as the MCP2221) connects to the USB Host (such as the
PC), the host will ask for the device’s Product and Vendor IDs (VID & PID).
The default values for the MCP2221 are 0x4D8 and 0xDD. In case any of these values
has been changed by the user, and the USB.inf driver file has been customized
accordingly and has been installed properly, then the PC application will report the
“MCP2221 not connected” error message. In such a case, the application can be
configured to look for a device with custom values by clicking the Using Custom
VID/PID… button.
Note: The MCP2221 I
2
C Demo Board Application does not rewrite the VID & PID
inside the MCP2221 board. This can be done using the MCP2221 Utility
which can be downloaded from http://www.microchip.com. However, extra
knowledge in terms of legal and technical implications is required.
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