
CHAPTER  17   CLOCKED  SERIAL  INTERFACE  A  (CSIA)  WITH  AUTOMATIC  TRANSMIT/RECEIVE  FUNCTION
User
’
s Manual  U15862EJ3V0UD
533
(b) Automatic transmission mode
In this mode, the specified number of 8-bit unit data are transmitted.
Serial transfer is started when the ATSTAn bit of serial trigger register n (CSITn) is set to 1 while the
CSIAEn, ATEn, and TXEAn bits of serial operating mode specification register n (CSIMAn) are set to 1.
When the final byte has been transmitted, an interrupt request flag (CSIAFn) is set.  However, judge the
termination of automatic transmission and reception, not by the INTCSIAn signal but by the TSFn bit of
serial status register n (CSISn).
Figure 17-8 shows the automatic transmission mode operation timing, and Figure 17-9 shows the
operation flowchart.  Figure 17-10 shows the operation of the internal buffer RAM when 6 bytes of data
are transmitted or received.
Figure 17-8.  Automatic Transmission Mode Operation Timing
SCKAn
SOAn
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0
CSIAFn
TSFn
Interval
Cautions 1. Because, in the automatic transmission mode, the automatic transmit/receive
function reads data from the internal buffer RAM after 1-byte transmission, an
interval is inserted until the next transmission.  As the buffer RAM read is
performed at the same time as CPU processing, the interval is dependent upon
the value of  automatic data transfer interval specification register n (ADTIn) (see
(6) Automatic transmit/receive interval time).
2. When the TSFn bit is cleared, the SOAn pin becomes low level.
Remarks 1.
 CSIAFn: Interrupt request flag
TSFn:
2.
 n = 0 (V850ES/KF1)
n = 0, 1 (V850ES/KG1, V850ES/KJ1)
Bit 0 of serial status register n (CSISn)