HD64336901G Renesas Technology, HD64336901G Datasheet - Page 237

• Manufacturer Part Number: HD64336901G
• Description: (HD64xxx Series) 16-BIT MICROCONTROLLER
• Manufacturer: Renesas Technology

14.5.3
Figure 14.11 shows an example of SCI3 operation for transmission in clocked synchronous mode.
In serial transmission, SCI3 operates as described below.
1. SCI3 monitors the TDRE flag in SSR, and if the flag is 0, SCI3 recognizes that data has been
2. SCI3 sets the TDRE flag to 1 and starts transmission. If the TIE bit in SCR3 is set to 1 at this
3. 8-bit data is sent from the TXD pin synchronized with the output clock when output clock
4. SCI3 checks the TDRE flag at the timing for sending the MSB (bit 7).
5. If the TDRE flag is cleared to 0, data is transferred from TDR to TSR, and serial transmission
6.
7.
Figure 14.12 shows a sample flow chart for serial data transmission. Even if the TDRE flag is
cleared to 0, transmission will not start while a receive error flag (OER, FER, or PER) is set to 1.
Make sure that the receive error flags are cleared to 0 before starting transmission.
TDRE
TEND
LSI
operation
User
processing
written to TDR, and transfers the data from TDR to TSR.
time, a transmit data empty interrupt (TXI) is generated.
mode has been specified, and synchronized with the input clock when use of an external clock
has been specified. Serial data is transmitted sequentially from the LSB (bit 0), from the TXD
pin.
of the next frame is started.
Serial
clock
Serial
data
If the TDRE flag is set to 1, the TEND flag in SSR is set to 1, and the TDRE flag maintains
the output state of the last bit. If the TEIE bit in SCR3 is set to 1 at this time, a TEI interrupt
request is generated.
The SCK3 pin is fixed high at the end of transmission.
Figure 14.11 Example of SCI3 Transmission in Clocked Synchronous Mode
Serial Data Transmission
TXI interrupt
request
generated
Bit 0
Bit 1
TDRE flag
cleared
to 0
Data written
to TDR
1 frame
TXI interrupt request generated
Bit 7
Bit 0
Bit 1
Rev. 1.00, 11/03, page 209 of 376
1 frame
Bit 6
TEI interrupt request
generated
Bit 7