Rainbow-electronics ATmega64C1 Manuel d'utilisateur télécharger pdf (Page 192)

192

7647A–AVR–02/08

ATmega32/64/M1/C1

• Bit 7– Reserved Bit

This bit is reserved for future use. For compatibility with future devices, it must be written to zero

when CANBT3 is written.

• Bit 6:4 – PHS22:0: Phase Segment 2

This phase is used to compensate for phase edge errors. This segment may be shortened by

the re-synchronization jump width. PHS2[2..0] shall be ≥1 and ≤PHS1[2..0] (c.f. Section 16.2.3

“CAN Bit Timing” on page 169 and Section 16.4.3 “Baud Rate” on page 175).

• Bit 3:1 – PHS12:0: Phase Segment 1

This phase is used to compensate for phase edge errors. This segment may be lengthened by

the re-synchronization jump width.

• Bit 0 – SMP: Sample Point(s)

This option allows to filter possible noise on TxCAN input pin.

– 0 - the sampling will occur once at the user configured sampling point - SP.

– 1 - with three-point sampling configuration the first sampling will occur two

Tclk

clocks before the user configured sampling point - SP, again at one

Tclk

clock

before SP and finally at SP. Then the bit level will be determined by a majority vote of

the three samples.

‘SMP=1’ configuration is not compatible with ‘BRP[5:0]=0’ because TQ =

Tclk

If BRP = 0, SMP must be cleared.

16.10.11 CAN Timer Control Register - CANTCON

• Bit 7:0 – TPRSC7:0: CAN Timer Prescaler

Prescaler for the CAN timer upper counter range 0 to 255. It provides the clock to the CAN timer

if the CAN controller is enabled.

Tclk

CANTIM

= Tclk

x 8 x (CANTCON [7:0] + 1)

16.10.12 CAN Timer Registers - CANTIML and CANTIMH

• Bits 15:0 - CANTIM15:0: CAN Timer Count

CAN timer counter range 0 to 65,535.

Tphs2 = Tscl x (PHS2 [2:0] + 1)

Tphs1 = Tscl x (PHS1 [2:0] + 1)

Bit 76543210

TPRSC7 TPRSC6 TPRSC5 TPRSC4 TPRSC3 TPRSC2 TRPSC1 TPRSC0 CANTCON

Read/Write R/W R/W R/W R/W R/W R/W R/W R/W

Initial Value00000000

Bit76543210

CANTIM7 CANTIM6 CANTIM5 CANTIM4 CANTIM3 CANTIM2 CANTIM1 CANTIM0 CANTIML

CANTIM15 CANTIM14 CANTIM13 CANTIM12 CANTIM11 CANTIM10 CANTIM9 CANTIM8 CANTIMH

Bit 15141312111098

Read/WriteRRRRRRRR

Initial Value00000000

1 2 ... 187 188 189 190 191 192 193 194 195 196 197 ... 365 366

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Rainbow-electronics ATmega64C1 Manuel d'utilisateur Page 192

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