Initialization (Clock Synchronous Mode) - Renesas RZ/A Series User Manual

RZ/A1L Group, RZ/A1LU Group, RZ/A1LC Group
[Conditions for low-level output]
Satisfaction of all conditions listed below
• The value of the RE or TE bit in the SCR is 1
• Neither transmission nor reception is in progress
• There are no received data yet to be read (when the SCR.RE bit is 1)
• Transmit data has been written (when the SCR.TE bit is 1)
• ORER flag in SSR is 0
[Condition for high-level output]
Any of the conditions for the low level not being satisfied
15.5.3

Initialization (Clock Synchronous Mode)

Before transmitting and receiving data, start by writing the initial value "00h" to the SCR and then continue through the
procedure for SCI given in the sample flowchart (Figure 15.18). Whenever the operating mode or transfer format is
changed, the SCR must be initialized before the change is made.
Note that clearing the SCR.RE bit to 0 initializes neither the ORER, FER, and PER flags in SSR nor RDR.
Moreover, note that switching the value of the SCR.TE bit from 1 to 0 or 0 to 1 while the SCR.TIE bit is 1 leads to the
generation of a TXI interrupt request.
Start initialization
Clear bits TIE, RIE, TE, RE, and TEIE in
SCR to 0
Set the general-purpose I/O port
Set bits CKE[1:0] in SCR
Set data transmission/reception format in
SMR and SCMR
Set a value in BRR
Set TE or RE bit in SCR to 1, and set TIE and
RIE bits in SCR
<Transmission/reception>
Note: • In simultaneous transmit and receive operations, the TE and RE bits in SCR should both be to 0 or
set to 1 simultaneously.
Figure 15.18 Example of Initialization Flowchart (Clock Synchronous Mode)
R01UH0437EJ0600 Rev.6.00
Jan 29, 2021
[ 1 ] Make general-purpose I/O port settings to enable
input and output functions as required for TXDn,
RXDn, and SCKn pins.
[ 2 ] Set the clock selection in SCR.
When an internal clock is selected, the SCK pin
functions as the clock output pin.
[ 1 ]
[ 3 ] Set the data transmission/reception format in SMR
[ 2 ]
and SCMR.
[ 4 ] Write a value corresponding to the bit rate to BRR.
[ 3 ]
This step is not necessary if an external clock is
used.
[ 4 ]
[ 5 ] Set the TE bit or RE bit in SCR to 1. Also set the
TIE and RIE bits in SCR.
Setting the TE and RE bits allows TXDn and RXDn
[ 5 ]
to be used.
15. Serial Communications Interface
15-40