MC68HC908GZ8 Datasheet, PDF (188/344 Pages) Motorola, Inc – Microcontrollers

MSCAN08 Controller (MSCAN08)
Table 16-7. Baud Rate Prescaler
BRP5
0
0
0
0
:
:
1
BRP4
0
0
0
0
:
:
1
BRP3
0
0
0
0
:
:
1
BRP2
0
0
0
0
:
:
1
BRP1
0
0
1
1
:
:
1
BRP0
0
1
0
1
:
:
1
Prescaler
Value (P)
1
2
3
4
:
:
64
NOTE: The CBTR0 register can be written only if the SFTRES bit in the MSCAN08 module
control register is set.
16.13.4 MSCAN08 Bus Timing Register 1
Address:
Read:
Write:
Reset:
$0503
Bit 7
6
5
4
3
2
1
SAMP TSEG22 TSEG21 TSEG20 TSEG13 TSEG12 TSEG11
0
0
0
0
0
0
0
Figure 16-18. Bus Timing Register 1 (CBTR1)
Bit 0
TSEG10
0
NOTE:
SAMP — Sampling
This bit determines the number of serial bus samples to be taken per bit time. If
set, three samples per bit are taken, the regular one (sample point) and two
preceding samples, using a majority rule. For higher bit rates, SAMP should be
cleared, which means that only one sample will be taken per bit.
1 = Three samples per bit⁽¹⁾
0 = One sample per bit
TSEG22–TSEG10 — Time Segment
Time segments within the bit time fix the number of clock cycles per bit time and
the location of the sample point. Time segment 1 (TSEG1) and time segment 2
(TSEG2) are programmable as shown in Table 16-8.
The bit time is determined by the oscillator frequency, the baud rate prescaler,
and the number of time quanta (T_q) clock cycles per bit as shown in Table 16-4).
Bit time =
Pres value
• number of time quanta
f_MSCANCLK
The CBTR1 register can only be written if the SFTRES bit in the MSCAN08 module
control register is set.
1. In this case PHASE_SEG1 must be at least 2 time quanta.
Data Sheet
188
MSCAN08 Controller (MSCAN08)
MC68HC908GZ8
Freescale Semiconductor