upd78f0148m1gka1-9eu Renesas Electronics Corporation., upd78f0148m1gka1-9eu Datasheet - Page 652

• Manufacturer Part Number: upd78f0148m1gka1-9eu
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

652
Serial
interface
UART6
Function
UART mode
TXB6: Transmit
buffer register 6
ASIM6:
Asynchronous
serial interface
operation mode
register 6
ASIS6:
Asynchronous
serial interface
reception error
status register 6
ASIF6:
Asynchronous
serial interface
transmission
status register 6 To initialize the transmission unit upon completion of continuous transmission, be
CKSR6: Clock
selection
register 6
Details of
Function
If clock supply to serial interface UART6 is not stopped (e.g., in the HALT mode),
normal operation continues. If clock supply to serial interface UART6 is stopped
(e.g., in the STOP mode), each register stops operating, and holds the value
immediately before clock supply was stopped. The T
immediately before clock supply was stopped and outputs it. However, the
operation is not guaranteed after clock supply is resumed. Therefore, reset the
circuit so that POWER6 = 0, RXE6 = 0, and TXE6 = 0.
If data is continuously transmitted, the communication timing from the stop bit to
the next start bit is extended two operating clocks of the macro. However, this
does not affect the result of communication because the reception side initializes
the timing when it has detected a start bit. Do not use the continuous
transmission function if UART6 is used in the LIN communication operation.
Do not write data to TXB6 when bit 1 (TXBF6) of asynchronous serial interface
transmission status register 6 (ASIF6) is 1.
Do not refresh (write the same value to) TXB6 by software during a
communication operation (when bit 7 (POWER6) and bit 6 (TXE6) of
asynchronous serial interface operation mode register 6 (ASIM6) are 1 or when
bit 7 (POWER6) and bit 5 (RXE6) of ASIM6 are 1).
At startup, set POWER6 to 1 and then set TXE6 to 1. To stop the operation, clear
TXE6 to 0, and then clear POWER6 to 0.
At startup, set POWER6 to 1 and then set RXE6 to 1. To stop the operation,
clear RXE6 to 0, and then clear POWER6 to 0.
Set POWER6 to 1 and then set RXE6 to 1 while a high level is input to the RxD6
pin. If POWER6 is set to 1 and RXE6 is set to 1 while a low level is input,
reception is started.
Clear the TXE6 and RXE6 bits to 0 before rewriting the PS61, PS60, and CL6
bits.
Fix the PS61 and PS60 bits to 0 when UART6 is used in the LIN communication
operation.
Make sure that TXE6 = 0 when rewriting the SL6 bit. Reception is always
performed with “the number of stop bits = 1”, and therefore, is not affected by the
set value of the SL6 bit.
Make sure that RXE6 = 0 when rewriting the ISRM6 bit.
The operation of the PE6 bit differs depending on the set values of the PS61 and
PS60 bits of asynchronous serial interface operation mode register 6 (ASIM6).
The first bit of the receive data is checked as the stop bit, regardless of the
number of stop bits.
If an overrun error occurs, the next receive data is not written to receive buffer
register 6 (RXB6) but discarded.
If data is read from ASIS6, a wait cycle is generated. Do not read data from
ASIS6 when the CPU is operating on the subsystem clock and the X1 input clock
is stopped. For details, see CHAPTER 36 CAUTIONS FOR WAIT.
To transmit data continuously, write the first transmit data (first byte) to the TXB6
register. Be sure to check that the TXBF6 flag is “0”. If so, write the next transmit
data (second byte) to the TXB6 register. If data is written to the TXB6 register
while the TXBF6 flag is “1”, the transmit data cannot be guaranteed.
sure to check that the TXSF6 flag is “0” after generation of the transmission
completion interrupt, and then execute initialization. If initialization is executed
while the TXSF6 flag is “1”, the transmit data cannot be guaranteed.
When the internal oscillation clock is selected as the clock to be supplied to the
CPU, the clock of the internal oscillator is divided and supplied as the count clock.
If the base clock is the internal oscillation clock, the operation of serial interface
UART6 is not guaranteed.
Make sure POWER6 = 0 when rewriting TPS63 to TPS60.
APPENDIX D LIST OF CAUTIONS
User’s Manual U15947EJ3V1UD
Cautions
X
D6 pin also holds the value
p. 311
p. 311
p. 317
p. 317
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