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2.4.2 Operation of Serial I/O (transmission in UART mode)
In transmitting data in UART mode, choose functions from those listed in Table 2.4.4. Operations of the
circled items are described below. Figure 2.4.7 shows the operation timing, and Figures 2.4.8 and 2.4.9
show the set-up procedures.
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Operation
Note
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
Table 2.4.4. Choosed functions
Item
Transfer clock
O
Internal clock (f
source
External clock (CLKi pin)
O
CTS function
CTS function enabled
CTS function disabled
Transmission
Transmission buffer empty
interrupt factor
O
Transmission complete
(1) Setting the transmit enable bit to "1" and writing transmission data to the UARTi transmit
buffer register readies the data transmissible status.
________
(2) When input to the CTSi pin goes to "L", transmission starts (the CTSi pin needs to be con-
trolled on the reception side).
(3) Transmission data held in the UARTi transmit buffer register is transmitted to the UARTi
transmit register. At this time, the first bit (the start bit) of the transmission data is transmitted
from the TxDi pin. Then, data is transmitted, bit by bit, in sequence: LSB, ····, MSB, parity bit,
and stop bit(s).
(4) When the stop bit(s) is (are) transmitted, the transmit register empty flag goes to "1", which
indicates that transmission is completed. At this time, the UARTi transmit interrupt request bit
goes to "1". The transfer clock stops at "H" level.
(5) If the transmission condition of the next data is ready when transmission is completed, a start
bit is generated following to stop bit(s), and the next data is transmitted.
_______
• Set CTSi pin's port direction register to "0".
page 64 of 354
Set-up
Item
Data logic select
/ f
/ f
)
1
8
32
function
T
D, R
D I/O
X
X
polarity reverse bit
Bus collision
detection function
2. UART
Set-up
O
No reverse
Reverse
No reverse
O
Reverse
Not selected
O
Selected
________
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