ST72521M7TC View Datasheet(PDF) - STMicroelectronics

Part Name

Description

MFG CO.

ST72521M7TC

8-BIT MCU WITH NESTED INTERRUPTS, FLASH, 10-BIT ADC, FIVE TIMERS, SPI, SCI, I2C, CAN INTERFACE

STMicroelectronics 

ST72521M/R/AR

CONTROLLER AREA NETWORK (Cont’d)

BAUD RATE PRESCALER REGISTER (BRPR)

Read/Write in Standby mode

Reset Value: 00h

7

0

RJW1 RJW0 BRP5 BRP4 BRP3 BRP2 BRP1 BRP0

BIT TIMING REGISTER (BTR)

Read/Write in Standby mode

Reset Value: 23h

7

0

0 BS22 BS21 BS20 BS13 BS12 BS11 BS10

RJW[1:0] determine the maximum number of time

quanta by which a bit period may be shortened or

lengthened to achieve resynchronization.

tRJW = tCAN * (RJW + 1)

BRP[5:0] determine the CAN system clock cycle

time or time quanta which is used to build up the in-

dividual bit timing.

tCAN = tCPU * (BRP + 1)

Where tCPU = time period of the CPU clock.

The resulting baud rate can be computed by the for-

mula:

BR

=

-----------------------------------------------1------------------------------------------------

tCPU × (BRP + 1) × (BS1 + BS2 + 3)

BS2[2:0] determine the length of Bit Segment 2.

tBS2 = tCAN * (BS2 + 1)

BS1[3:0] determine the length of Bit Segment 1.

tBS1 = tCAN * (BS1 + 1)

Note: Writing to this register is allowed only in

Standby mode to prevent any accidental CAN pro-

tocol violation through programming errors.

PAGE SELECTION REGISTER (PSR)

Read/Write

Reset Value: 00h

7

0

0

0

0

0

0 PAGE PAGE PAGE

2

1

0

Note: Writing to this register is allowed only in

Standby mode to prevent any accidental CAN pro-

tocol violation through programming errors.

PAGE[2:0] determine which buffer or filter page is

mapped at addresses 0010h to 001Fh.

PAGE2

0

0

0

0

1

1

1

1

PAGE1

0

0

1

1

0

0

1

1

PAGE0

0

1

0

1

0

1

0

1

Page Title

Diagnosis

Buffer 1

Buffer 2

Buffer 3

Filters

Reserved

Reserved

Reserved

137/199

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