IA82527_13 Datasheet, PDF (30/58 Pages) InnovASIC, Inc – Serial Communications Controller—CAN Protocol

IA82527
CAN Serial Communications Controller
Data Sheet
December 20, 2012
4.1.3 I/O Ports
The IA82527 contains two 8-bit General Purpose Input Output (GPIO) ports. Each GPIO port is
selectable or programmable as either an input or an output. CPU interface modes may use some
of the GPIO pins or signals, precluding their use as GPIO. Six bits of GPIO Port 2 (p2.5 to p2.0)
are always available as GPIO. GPIO Port 2 bits 6 and 7 (p2.6 and p2.7) have alternate functions
as the alternate source for int_n and as the wrh_n input for CPU mode 2 and may be available as
GPIO depending on the CPU mode. GPIO Port 1 is available for use as GPIO in CPU
modes 0, 2, and SPI and is not available in CPU modes 1 and 3.
4.1.4 Programmable Clock Output
Using an oscillator, clock divider register, and a driver circuit, the IA82527 provides a
programmable clock output. The output frequency range available is from the external crystal
frequency to that frequency divided by 15. The clock output allows the IA82527 to drive other
devices such as the host CPU. The slew rate of the clkout signal is selectable via the CLKOUT
Register (1FH).
4.2 Address Map
The IA82527 includes 256 8-bit locations that provide device configuration registers and
message storage. The address map is shown in Table 8.
4.3 CAN Message Objects
Each CAN message object has a unique identifier and can be configured as either transmit or
receive, except for message object 15. Message object 15 is a double-buffered receive-only
buffer with a special mask design to allow select groups of different message identifiers to be
received. Each message object contains registers for control and status bits.
All message objects have separate transmit and receive interrupts and status bits that allow the
host CPU to determine when a message frame has been sent or received. The IA82527
implements a global masking feature that allows the user to globally mask any identifier bits of
the incoming message. This mask is programmable, which permits application-specific message
identification.
The Message Object Structure is shown in Table 9.
IA211080504-07
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