82C900 Datasheet, PDF (8/29 Pages) Infineon Technologies AG – Standalone TwinCAN Controller

82C900
Preliminary
Connection to a Host Device via the Serial Interface
The second possibility to connect the 82C900 to a host device is via the serial interface.
This mode is selected if the pin MODE0=1 and MODE1=0.
The standard four-line SPI-compatible interface has been extended by a RDY signal,
which indicates that the serial interface is ready for the next access by the host.
The page size is reduced to 128 bytes per page, because the MSB of the address byte
contains a read/write indication. A special incremental access mode has been
implemented in order to reduce significantly the number of transferred bytes for
consecutive register accesses.
The 8 remaining I/O pins from the unused parallel interface are controlled by a port
control logic and can be used as I/O extension. These lines can be read or written by the
serial channel or by CAN messages. Furthermore, these lines can be programmed as
additional interrupt output lines in order to increase the number of independent
interrupts.
The output lines OUT0 and OUT1 have the same functionality in the case a parallel
interface or a serial interface connects the 82C900 to a host device.
Figure 3
CAN Bus A
CAN Bus B
Transceiver
Transceiver
RXDCA,
TXDCA
RXDCB,
TXDCB
82C900
TwinCAN Module
Clock Control
Port Control Serial Interface
Interrupt
Control
I/O7..0
Input/Output
Extension
CTRL3..0 RDY
Host
OUTx
Host Connection via the Serial Interface
Data Sheet
8
V 1.0D3, 2001-03