CHAPTER 11 FCAN CONTROLLER
618
User’s Manual U14492EJ3V0UD
Given the above limit values, the following three settings are possible.
Prescaler
DBT
SPT (MAX.)
Calculated SPT
16
12
8
8/12 = 67%
12
16
12
12/16 = 75%
8
24
17
17/24 = 71%
16 MHz/83 kbps
≅
192 = 64
×
3
<1>
= 48
×
4
<2>
= 32
×
6
<3>
= 24
×
8
<4>
= 16
×
12
<5>
= 12
×
16
<6>
= 8
×
24
<7>
= 6
×
32
<8>
= 4
×
48
<9>
= 3
×
64
<10>
The settings that can actually be made for the V850E/IA1 are in the range from <5> to <7> above (the section
enclosed in broken lines).
Among these options in the range from <5> to <7> above, option <6> is the ideal setting for used when
actually setting the register.
(i) Prescaler (CAN protocol layer base system clock: f
BTL
) setting
f
BTL
is calculated as below.
•
f
BTL
= f
MEM
/{(a + 1)
×
2} : [0
≤
a
≤
63]
Value a is set using bits 5 to 0 (BRP5 to BRP0) of the C1BRP register.
f
BTL
= 16 MHz/12
= 16 MHz/{(5 + 1)
×
2}
thus a = 5
Therefore, C1BRP register = 0005H
Содержание V850E/IA1 mPD703116
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