BeagleBone RS232 Cape
System Reference Manual
Revision A
Page 19 of 22
connector J1 is received by the SN65C322EPW and transmitted as UART data.
Similarly, UART data from BeagleBone is translated to RS232 before transmitted to the
D-Sub 9 connector. The data signaling rate can go up to 1 Mbps.
On the BeagleBone RS232 Cape, enable signal (EN) is pulled low and FORCEOFF is
high to enable the data translation between RS232 and UART.
Figure 5 shows SN65C322EPW in RS232 schematic.
Figure 5.
UART to RS232
5.5
EEPROM
The BeagleBone RS232 Cape has an EEPROM containing information that will allow the
SW to identify the board and to configure the expansion headers pins as needed.
EEPROMs are required for all Capes sold in order for them to operate correctly when
plugged in the BeagleBone.
The EEPROM used on this cape is the same one as is used on the BeagleBone, a
CAT24C256. The CAT24C256 is a 256 kb Serial CMOS EEPROM, internally organized
as 32,768 words of 8 bits each. It features a 64-byte page write buffer and supports the
Standard (100 kHz), Fast (400 kHz) and Fast-Plus (1 MHz) I2C protocol. Figure 6 is the
design of the EEPROM circuit.
