Toshiba TMP91C824F Data Book page 132

Handshake function
Serial Channels 0, 1 each has a CTS pin. Use of this pin allows data can be sent in units of one
frame; thus, Overrun errors can be avoided. The handshake functions is enabled or disabled by the
SC0MOD <CTSE> setting.
When the CTS0 pin foes High on completion of the current data send, data transmission is halted
until the CTS0 pin foes Low again. However, the INTTX0 Interrupt is generated, it requests the next
data send to the CPU. The next data is written in the Transmission Buffer and data sending is halted.
Though there is no RTS pin, a handshake function can be easily configured by setting any port
assigned to be the RTS function. The RTS should be output "High" to request send data halt after
data receive is completed by software in the RXD interrupt routine.
Timing to writing to the
Transmission Buffer
Send is suspended
during this period
CTS
①
SIOCLK
TXDCLK
TXD
(note1): If the CTS signal goes High during transmission, no more data will be sent after completion of the
current transmission.
(note2): Transmission starts on the first falling edge of the TXDCLK clock after the CTS signal has fallen.
91C824
TXD
CTS
Sender
Figure 3.9.5 Handshake function
"
13 14 15 16
Figure 3.9.6 CTS (Clear to send) Timing
91C824-129
91C824
RXD
RTS (any port)
Receiver
1 2 3 14
start bit
TMP91C824
15 16 1 2 3
bit 0