Datasheet
78K0/Ix2 CHAPTER 14 SERIAL INTERFACE UART6/DALI
R01UH0010EJ0500 Rev.5.00 452
Feb 28, 2012
(d) Continuous transmission
The next transmit data can be written to UART/DALI transmit buffer register 6 (TXB6) as soon as UART/DALI
transmit shift register 6 (TXS6) has started its shift operation. Consequently, even while the INTST6 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 TXB6 register can be efficiently written twice (2 bytes)
without having to wait for the transmission time of one data frame, by reading bit 0 (TXSF6) of UART
transmission status register 6 (ASIF6) when the transmission completion interrupt has occurred.
To transmit data continuously, be sure to reference the ASIF6 register to check the transmission status and
whether the TXB6 register can be written, and then write the data.
Cautions 1. The TXBF6 and TXSF6 flags of the ASIF6 register change from “10” to “11”, and to “01”
during continuous transmission. To check the status, therefore, do not use a combination
of the TXBF6 and TXSF6 flags for judgment. Read only the TXBF6 flag when executing
continuous transmission.
2. When the device is use in LIN communication operation, the continuous transmission
function cannot be used. Make sure that asynchronous serial interface UART transmission
status register 6 (ASIF6) is 00H before writing transmit data to UART/DALI transmit buffer
register 6 (TXB6).
TXBF6 Writing to TXB6 Register
0 Writing enabled
1 Writing disabled
Caution 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.
The communication status can be checked using the TXSF6 flag.
TXSF6 Transmission Status
0 Transmission is completed.
1 Transmission is in progress.
Cautions 1. To initialize the transmission unit upon completion of continuous transmission, be 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.
2. During continuous transmission, the next transmission may complete before execution of
INTST6 interrupt servicing after transmission of one data frame. As a countermeasure,
detection can be performed by developing a program that can count the number of transmit
data and by referencing the TXSF6 flag.