NEC PD78076 User Manual page 442

In 6-byte transmission (ARLD = 0, RE = 0) in basic transmit mode, buffer RAM operates as follows.
(i) Before transmission (refer to Figure 19-13 (a))
After any data has been written to the serial I/O shift register 1 (SIO1) (start trigger: this data is not
transferred), transmit data 1 (T1) is transferred from the buffer RAM to SIO1. When transmission
of the first byte is completed, the automatic data transmit/receive address pointer (ADTP) is
decremented. Then transmit data 2 (T2) is transferred from the buffer RAM to SIO1.
(ii) 4th byte transmission point (refer to Figure 19-13 (b))
Transmission of the third byte is completed, and transmit data 4 (T4) is transferred from the buffer
RAM to SIO1. When transmission of the fourth byte is completed, ADTP is decremented.
(iii) Completion of transmission/reception (refer to Figure 19-13 (c))
When transmission of the sixth byte is completed, the interrupt request flag (CSIIF1) is set (INTCSI1
generation).
Figure 19-13. Buffer RAM Operation in 6-byte Transmission
FADFH
FAC5H
FAC0H
442
CHAPTER 19 SERIAL INTERFACE CHANNEL 1
(in Basic Transmit Mode) (1/2)
(a) Before transmission
Transmit data 1 (T1)
Transmit data 2 (T2)
Transmit data 3 (T3)
Transmit data 4 (T4)
Transmit data 5 (T5)
Transmit data 6 (T6)
SIO1
5 ADTP
–1
0 CSIIF1