CHAPTER 12 SERIAL INTERFACE UART6
Preliminary User’s Manual U16846EJ1V0UD
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(g) Noise filter of receive data
The RXD6 signal is sampled with the base clock output by the prescaler block.
If two sampled values are the same, the output of the match detector changes, and the data is sampled as
input data.
Because the circuit is configured as shown in Figure 12-21, the internal processing of the reception operation
is delayed by two clocks from the external signal status.
Figure 12-21. Noise Filter Circuit
Internal signal B
Internal signal A
Match detector
In
Base clock
R
X
D6/P14
Q
In
LD_EN
Q
(h) SBF transmission
When the device is incorporated in LIN, the SBF (Synchronous Break Field) transmission control function is
used for transmission. For the transmission operation of LIN, see Figure 12-1 LIN Transmission
Operation.
An SBF length of a low level of 13 bits or more is set by bits 4 to 2 (SBL62 to SBL60) of asynchronous serial
interface control register 6 (ASICL6). If more precise output width adjustment is necessary, use the baud
rate value of the normal UART transmission function.
[Setting method]
Transmit 00H by setting the number of character bits of the data to 8 bits and the parity bit to 0 parity or even
parity. This enables a low-level transmission of a data frame consisting of 10 bits (1 bit (start bit) + 8 bits
(character bits) + 1 bit (parity bit)).
Adjust the baud rate value to make this 10-bit low level the targeted 13-bit SBF length (SBL62, SBL61,
SBL60 = 1, 0, 1).
Example If LIN is to be transmitted under the following conditions
•
Base clock of UART6 = 5 MHz (set by clock selection register 6 (CKSR6))
•
Target baud rate value = 19200 bps
To realize the above baud rate value, the length of a 13-bit SBF is as follows if the baud rate generator
control register 6 (BRGC6) is set to 130.
•
13-bit SBF length = 0.2
µ
s
×
130
×
2
×
13 = 676
µ
s
To realize a 13-bit SBF length in 10 bits, set a value 1.3 times the targeted baud rate to BRGC6. In this
example, set 169 to BRGC6. The transmission length of a 10-bit low level in this case is as follows, and
matches the 13-bit SBF length.
•
10-bit low-level transmission length = 0.2
µ
s
×
169
×
2
×
10 = 676
µ
s
If the number of bits set by BRGC6 runs short, adjust the number of bits by setting the base clock of
UART6.