MCP2510-SLASHST datasheet(52/80 Pages) MICROCHIP

52 / 80 page

MCP2510

DS21291F-page 52

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.

CANCTRL - CAN CONTROL REGISTER (ADDRESS: XFh)

R/W-1

R/W-0

U-0

R/W-1

REQOP2

REQOP1

REQOP0

ABAT

—

CLKEN

CLKPRE1 CLKPRE0

bit 7

bit 0

bit 7-5

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’

bit 4

ABAT: Abort All Pending Transmissions

= Request abort of all pending transmit buffers

= Terminate request to abort all transmissions

bit 3

Unimplemented: Read as '0'

bit 2

CLKEN: CLKOUT Pin Enable

= CLKOUT pin enabled

= CLKOUT pin disabled (Pin is in high impedance state)

bit 1-0

CLKPRE <1:0>: CLKOUT Pin Prescaler

=FCLKOUT = System Clock/1

=FCLKOUT = System Clock/2

=FCLKOUT = System Clock/4

=FCLKOUT = System Clock/8

Legend:

R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

’1’ = Bit is set

’0’ = Bit is cleared

x = Bit is unknown

MCP2510-/ST 数据表(PDF) 52 Page - Microchip Technology

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