User manual

Getting Started
 2015 Microchip Technology Inc. DS40001812A-page 25
2.4.1 USB-to-UART Interface
The MCP2221 supports baud rates between 300 and 115200. It utilizes a set of
commands to read and set the UART parameters during operation. It only supports
eight Data bits, no Parity, and one Stop bit. The terminal program (e.g., Teraterm,
Realterm, etc.) must be configured with the same settings.
If the MCU is configured to communicate with the host PC via UART interface, jumpers
J53, J54, J55 and J56 must be setup properly. The tutorial program in the PIC16F1719
implements the UART for MCU-to-PC communication. Figure 2-5 shows how to setup
the jumpers for the tutorial program. The MCU is configured for Transmit mode so only
J54 is utilized and the other jumpers are left disconnected.
FIGURE 2-5: SETUP FOR UART TRANSMIT MODE
The operating system searches for a driver once the Explorer 8 Development Board is
connected to the PC using the USB-to-UART interface. After a suitable driver is found,
the system creates an entry in the registry. The entry stores relevant information about
the USB-to-UART adapter, its driver and the associated COM port.
2.4.2 USB-to-I
2
C Interface
For the USB-to-I
2
C interface, the MCP2221 functions as an I
2
C Master to the PIC MCU
and uses USB HID (Human Interface Device) protocol for communication with a host
PC. A typical command exchange starts with a 64-byte packet that is written by the host
PC. Afterward, the PC reads the response USB-to-I
2
C from the device as a 64-byte
packet.
To use the Explorer 8 Development Board for I
2
C interface, jumpers J22, J23, J57 and
J58 must be configured properly. See Labels 1, 2 and 3 of Table 1-1 for sample jumper
configurations.
J54
RC4
RC6