2.3 Serial I/O
2-40
APPLICATION
3802 GROUP USER’S MANUAL
Control procedure :
When the registers are set as shown in Fig. 2.3.25, the Serial I/O1 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 2.3.27 shows a control procedure of serial I/O1.
P5 (Address : 0A
16
), bit3 0
0
N
Y
1
IREQ1 (Address : 3C
16
), bit3
Complete to transmit data
Initialization
.
SIO1CON
UARTCON
BRG
ICON1
P5
P5D
.
(Address : 1A
16
)
(Address : 1B
16
), bit4
(Address : 1C
16
)
(Address : 3E
16
), bit3
(Address : 0A
16
), bit3
(Address : 0B
16
)
11011000
2
XXXX
1
XXX
2
IREQ1 (Address : 3C
16
), bit3 0
TB/RB (Address : 18
16
)
P5 (Address : 0A
16
), bit3 1
a transmission
data
X
: This bit is not used in this application.
Set it to “0” or “1.” It’s value can be disregarded.
Set the Serial I/O1.
Set the CS signal output level to “L.”
Set the Serial I/O1 transmit interrupt
request bit to “0.”
Write a transmission data.
(start to transmit 1-byte data)
Check the completion of transmitting 1-
byte data.
Use any of RAM area as a counter for
counting the number of transmitted bytes.
Check that transmission of the target
number of bytes has been completed.
Return the CS signal output level to “H”
when transmission of the target number of
bytes is completed.
G
G
G
G
G
G
G
G
G
G
Serial I/O1 transmit interrupt : Disabled
Set the CS signal output port.
(“H” level output)
RESET
G
0
8–1
0
1
Fig. 2.3.27 Control procedure of serial I/O1 [Output of serial data]