M38002M4 Datasheet, PDF (86/173 Pages) Mitsubishi Electric Semiconductor – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.3 Serial I/O
Control procedure : When the registers are set as shown in Figure 2.3.21, the Serial I/O can transmit
1-byte data simply by writing data to the Transmit buffer register.
Thus, after setting the CS signal to “L,” write the transmission data to the
Receive buffer register on a 1-byte base, and return the CS signal to “H” when
the desired number of bytes have been transmitted.
Figure 2.3.23 shows a control procedure of serial I/O.
RESET
Initialization
SIOCON (Address : 1A16)
110110002
UARTCON (Address : 1B16), bit4 0
BRG
(Address : 1C16)
8–1
ICON1 (Address : 3E16), bit3 0
P5
(Address : 0A16), bit3 1
P5D
(Address : 0B16)
XXXX1XXX2
q X : This bit is not used in this application.
Set it to “0” or “1.” It’s value can be disregarded.
q _{Set the Serial I/O.}
q _{Serial I/O transmit interrupt : Disabled}
q _{Set the CS signal output port.}
(“H” level output)
P5 (Address : 0A16 ), bit3 0
IREQ1 (Address : 3C16 ), bit3 0
TB/RB (Address : 1816 )
a transmission
data
IREQ1 (Address : 3C16 ), bit3?
0
1
N
Complete to transmit data?
Y
P5 (Address : 0A16 ), bit3 1
q _{Set the CS signal output level to “L.”}
q _{Set the Serial I/O transmit interrupt}
request bit to “0.”
q _{Write a transmission data.}
(start to transmit 1-byte data)
q _{Check the completion of transmitting 1-}
byte data.
q _{Use any of RAM area as a counter for}
counting the number of transmitted bytes.
q _{Check that transmission of the target}
number of bytes has been completed.
q _{Return the CS signal output level to “H”}
when transmission of the target number of
bytes is completed.
Fig. 2.3.23 Control procedure of serial I/O [Output of serial data]
2-38
3800 GROUP USER’S MANUAL