Microchip Technology DV164139 Data Sheet
© 2009 Microchip Technology Inc.
DS41356B-page 29
2.7.1
Overview of the CDC – Serial Emulator Firmware
The CDC Serial Emulator firmware flow is shown in Figure 2-6.
FIGURE 2-6:
FLOWCHART FOR CDC SERIAL EMULATOR CODE
RS232 OUT Buffer available
and
USB OUT Buffer NOT EMPTY
YES
YES
Copy USB OUT Buffer
to RS232 OUT Buffer
Copy next byte to
EUSART
Copy USB IN Buffer to
USB Buffer
Add byte to RS232
IN Buffer
RS232 OUT Buffer NOT EMPTY
and
EUSART is EMPTY
EUSART has
a byte
YES
YES
RS232 IN Buffer
has data and
USB IN Buffer available
CDCTxService( )
ProcessIO( )
NO
NO
NO
NO