Operation; Transmission In Uart Mode - Renesas M16C Series User Manual

M30240 Group

2.5.2 Operation

2.5.2.1 Transmission in UART mode

For transmitting data in UART mode, select functions from those listed in Table 2.20 . An example using
the indicated options is described below. Figure 2.62 shows the operation timing, and Figure 2.63 and
Figure 2.64 show the set-up procedures.
Table 2.20: Serial I/O transmission in UART mode functions
Item
O
Transfer clock source
O
CTS function
Transmission
interrupt factor
O
Note 1: UART0, UART1 only.
Note 2: UART2 only.
Operation
(1) Setting the transmit enable bit to "1" and writing transmission data to the UARTi transmit buffer reg-
ister readies the data transmissible status.
(2) When the input to the CTSi pin goes to "L", transmission starts (the CTSi pin needs to be controlled
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 indi-
cates 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 the stop bit(s), and the next data is transmitted.
Rev.1.00 Sep 24, 2003 Page 210 of 360
Set-up
Internal clock (f1/f8/f32)
External clock (CLKi pin)
CTS function enabled
CTS function disabled
Transmission buffer empty
Transmission comlpete
Clock-Asynchronous Serial I/O
Item
O
Sleep mode (Note 1)
O
Data logic select function
(Note 2)
O
TxD, RxD I/O polarity
reverse bit (Note 2)
O
Bus collision detection
function (Note 2)
Set-up
Sleep mode off
Sleep mode on
No reverse
Reverse
No reverse
Reverse
Not selected
Selected