BeagleBone CANBus Cape
System Reference Manual
Revision A1
Page 18 of 21
As of this revision, the BeagleBone CANBus Cape uses the same printed circuit board
(PCB) as other serial capes; therefore, the controller signals RX and TX are connected to
a UART selection circuit where user can select which UART port is used. However,
since only UART1 port supports DCAN1, the jumpers of other UART ports are removed
on the CANBus Cape and the RXD and TXD jumpers of UART1 are hard-wired. Figure
5 shows the UART selection circuit on the CANBus Cape.
Figure 5.
UART Selection Circuit
5.5
EEPROM
The BeagleBone CANBus 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.
