TMP91C824
91C824-131
2008-02-20
Handshake function
Use of
CTS
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
0
CTS
pin goes high on completion of the current data send, data
transmission is halted until the
0
CTS
pin goes 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.
Figure 3.9.5 Handshake Function
Note 1: If the
CTS
signal goes high during transmission, no more data will be sent after completion of the
current transmission.
Note 2: Transmission starts on the first falling edge of the TXDCLK clock after the
CTS
signal has fallen.
Figure 3.9.6
CTS
(Clear to send) Timing
RXD
RTS
(Any port)
Receiver
TXD
CTS
TMP91C824
Sender
TMP91C824
Timing to writing to the
transmission buffer
CTS
a
b
13
14
15
16
1
2
3
14
15 16 1 2 3
SIOCLK
TXDCLK
TXD
Bit0
Start bit
Send is suspended
during this period