NEC uPD78P078 - Manual (Page 446)

446
CHAPTER 19 SERIAL INTERFACE CHANNEL 1
In 6-byte transmission (ARLD = 1, RE = 0) in repeat transmit mode, buffer RAM operates as follows.
(i) Before transmission (refer to Figure 19-16 (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) Upon completion of transmission of 6 bytes (refer to Figure 19-16 (b))
When transmission of the sixth byte is completed, the interrupt request flag (CSIIF1) is not set.
The first pointer value is set to ADTP again.
(iii) 7th byte transmission point (refer to Figure 19-16 (c))
Transmit data 1 (T1) is transferred from the buffer RAM to SIO1 again. When transmission of the
first byte is completed, ADTP is decremented. Then transmit data 2 (T2) is transferred from the
buffer RAM to SIO1.
Figure 19-16. Buffer RAM Operation in 6-byte Transmission
(in Repeat 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)
FADFH
FAC5H
FAC0H
SIO1
0 CSIIF1
5 ADTP
–1