7630_03 Datasheet, PDF (117/238 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

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2.4 Controller Area Network (CAN) module
• Auto-receive function
If receiving of CAN frames originating by the module itself are not required, the auto-receive disable bit CREC.6
(Figure 2.4.16) should be set.
• CAN interrupts
The module features six interrupts, each of them can be either enabled or disabled by the corresponding control
bits of the interrupt control registers ICONA and ICONB; refer to section 2.4.11.
• Enable CAN transmit pin
Configure Port P3₁/CTX as CAN transmit output pin by setting the port double function control bit CTRM.2 (Fig-
ure 2.4.3) before starting the communication functions of the module.
Example
Figure 2.4.28 shows an example of the initialization sequence required. At first, the module is switched to
configuration mode (for details refer to section 2.4.4) to enable altering the special function registers. After
that, the related SFRs are initialized with the corresponding parameters (see below). Finally, the module is
switched to normal (run) mode to enable the communication and to protect the critical SFRs from being
altered accidentally.
The following table shows the conditions being used below:
Item
Setting Description
Acceptance filtering
T_pts
T_pbs1
T_pbs2
Prescaler division ratio
Resynchronisation jump width
Sampling
Dominant polarity
Auto-receive
CAN interrupts
1
4
4
1
4
single
low
disabled
Filtering disabled; accept all identifiers.
These settings result in 10 time quanta per bit; the corre-
sponding baudrate is 500kbps at f(XIN) = 10MHz (equiva-
lent to fφ=5MHz).
not defined here (should be initialized)
These conditions result in CAN bus timing control register values of CBTCON1=00₁₆ and CBTCON2=DB₁₆.
7630 Group User’s Manual
2-51