UPD78F0838 Renesas Electronics Corporation., UPD78F0838 Datasheet - Page 412

• Manufacturer Part Number: UPD78F0838
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

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(d) Continuous transmission
The next transmit data can be written to transmit buffer register 6n (TXB6n) as soon as transmit shift register
6 (TXS6n) has started its shift operation. Consequently, even while the INTST6n interrupt is being serviced
after transmission of one data frame, data can be continuously transmitted and an efficient communication
rate can be realized. In addition, the TXB6n register can be efficiently written twice (2 bytes) without having
to wait for the transmission time of one data frame, by reading bit 0 (TXSF6n) of asynchronous serial
interface transmission status register 6n (ASIF6n) when the transmission completion interrupt has occurred.
To transmit data continuously, be sure to reference the ASIF6n register to check the transmission status and
whether the TXB6n register can be written, and then write the data.
Caution To transmit data continuously, write the first transmit data (first byte) to the TXB6n register.
The communication status can be checked using the TXSF6n flag.
Cautions 1. To initialize the transmission unit upon completion of continuous transmission, be sure
Remark n = 0, 1
Cautions 1. The TXBF6n and TXSF6n flags of the ASIF6n register change from “10” to “11”, and to
TXBF6n
TXSF6n
Be sure to check that the TXBF6n flag is “0”. If so, write the next transmit data (second
byte) to the TXB6n register. If data is written to the TXB6n register while the TXBF6n flag
is “1”, the transmit data cannot be guaranteed.
2. During continuous transmission, an overrun error may occur, which means that the
2. When the device is used in LIN communication operation, the continuous
0
1
0
1
to check that the TXSF6n flag is “0” after generation of the transmission completion
interrupt, and then execute initialization. If initialization is executed while the TXSF6n
flag is “1”, the transmit data cannot be guaranteed.
next transmission was completed before execution of INTST6n interrupt servicing after
transmission of one data frame. An overrun error can be detected by developing a
program that can count the number of transmit data and by referencing the TXSF6n flag.
“01” during continuous transmission. To check the status, therefore, do not use a
combination of the TXBF6n and TXSF6n flags for judgment. Read only the TXBF6n
flag when executing continuous transmission.
transmission function cannot be used. Make sure that asynchronous serial interface
transmission status register 6n (ASIF6n) is 00H before writing transmit data to
transmit buffer register 6n (TXB6n).
CHAPTER 12 SERIAL INTERFACES UART60 AND UART61
Writing enabled
Writing disabled
Transmission is completed.
Transmission is in progress.
Preliminary User’s Manual U19748EJ1V0UD
Writing to TXB6 Register
Transmission Status