DS41356B datasheet(35/54 Pages) MICROCHIP

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DS41356B-page 31

FIGURE 2-7:

CDCTXSERVICE( ) STATE DIAGRAM

2.7.2

Procedure

This application requires significant changes to the usb_descriptor.c file to configure

the PIC18F14K50 as a CDC device. Note the absence of the report descriptor. The

user is encouraged to spend some time reviewing the usb_descriptor.c file and com-

pare it against the information found in the Universal Serial Bus Class Definitions for

Communications Devices document referenced at the beginning of this chapter. Note

that this lab applies the same firmware found in the CDC – Serial Emulator application

example in Microchip’s Full-Speed USB Firmware Framework application examples

and can be used as a reference for this lab.

Create a new project for lab 4, using the Project Wizard, called “Project Lab 4”

as was done in the previous labs. The only files added, at this point, will be the

usb_descriptor.c

and main.c source files, as well as a new unique descrip-

tor for Lab 4 rm18f14k50.lkr can be found in:

C:\LPCUSBDK_Labs\Lab4_files

Step through to close the Project Wizard. This time, the project will be set up to

resemble the application examples in the Framework using sub-folders to distin-

guish and organize the different source files in the Project window. All remaining

source/header files will be added from the Project window.

Right click on the Source Files folder in the Project window and select Create

Subfolder...

CDC_TX_READY

CDC_TX_BUSY

CDC_TX_COMPLETING

CDC_TX_BUSY_ZLP

cdc_tx_lenl=0

cdc_tx_len==0

CDC_BULK_BD_IN.Cnt <Max EP Size

cdc_tx_len==0

CDC_BULK_BD_IN.Cnt <Max EP Size

mCDCUsartTxlsBusy()==0

CDC_BULK_BD_IN.Cnt==0

DS41356B Datasheet(PDF) 35 Page - Microchip Technology