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Using the AT89RFD-08 Board
AT89RFD-08 Hardware User Guide
2-11
4382E–MP3–05/06
2.4
Communication
Interfaces
2.4.1
RS-232
The AT89C51SND2C features an on-chip UART interface directly wired to SIP3
connector.
Caution: The AT89RFD-08 Board is supplied without any RS-232 driver/receiver.
Voltage levels on the RS232 interface shall be compliant with AT89C51SND2C DC
characteristics specified in the AT89C51SND2C datasheet.
Figure 2-9.
RS-232 SIP3 Connector
2.4.2
USB
The AT89RFD-08 Reference Design provides all the required hardware to develop USB
compliant application. This includes:
n a USB connector
n a USB unload jumper (J13) which allows to disconnect the pull-up on D+ and then
simulate an Attach/Detach of the USB cable.
n a USB VBUS detection capability is given by using P3.3 & P3.4 of the microcontroller
Figure 2-10.
USB Connector
3V UART