MCP2510I-ST Datasheet, PDF (52/80 Pages) Microchip Technology – Stand-Alone CAN Controller with SPI™ Interface

MCP2510
counters are reset and deactivated in this state. The lis-
ten-only mode is activated by setting the mode request
bits in the CANCTRL register.
9.4 Loopback Mode
This mode will allow internal transmission of messages
from the transmit buffers to the receive buffers without
actually transmitting messages on the CAN bus. This
mode can be used in system development and testing.
In this mode the ACK bit is ignored and the device will
allow incoming messages from itself just as if they were
coming from another node. The loopback mode is a
silent mode, meaning no messages will be transmitted
while in this state, including error flags or acknowledge
signals. The TXCAN pin will be in a reccessive state
while the device is in this mode. The filters and masks
can be used to allow only particular messages to be
loaded into the receive registers. The masks can be set
to all zeros to provide a mode that accepts all mes-
sages. The loopback mode is activated by setting the
mode request bits in the CANCTRL register.
9.5 Normal Mode
This is the standard operating mode of the MCP2510.
In this mode the device actively monitors all bus mes-
sages and generates acknowledge bits, error frames,
etc. This is also the only mode in which the MCP2510
will transmit messages over the CAN bus.
REGISTER 9-1:
CANCTRL - CAN CONTROL REGISTER (ADDRESS: XFh)
R/W-1
REQOP2
bit 7
R/W-1
REQOP1
R/W-1
REQOP0
R/W-0
ABAT
U-0
R/W-1 R/W-1 R/W-1
—
CLKEN CLKPRE1 CLKPRE0
bit 0
bit 7-5
bit 4
bit 3
bit 2
bit 1-0
REQOP<2:0>: Request Operation Mode
000 = Set Normal Operation Mode
001 = Set Sleep Mode
010 = Set Loopback Mode
011 = Set Listen Only Mode
100 = Set Configuration Mode
All other values for REQOP bits are invalid and should not be used
Note: On power up, REQOP = b’111’
ABAT: Abort All Pending Transmissions
1 = Request abort of all pending transmit buffers
0 = Terminate request to abort all transmissions
Unimplemented: Read as '0'
CLKEN: CLKOUT Pin Enable
1 = CLKOUT pin enabled
0 = CLKOUT pin disabled (Pin is in high impedance state)
CLKPRE <1:0>: CLKOUT Pin Prescaler
00 = FCLKOUT = System Clock/1
01 = FCLKOUT = System Clock/2
10 = FCLKOUT = System Clock/4
11 = FCLKOUT = System Clock/8
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
’1’ = Bit is set
U = Unimplemented bit, read as ‘0’
’0’ = Bit is cleared x = Bit is unknown
DS21291F-page 52
© 2007 Microchip Technology Inc.