HD64F2168 Datasheet, PDF (450/874 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer

372 clock cycles
186 clock
cycles
0
185
371 0
Internal
basic clock
185
371 0
Receive data
(RxD)
Start bit
D0
D1
Synchronization
sampling timing
Data sampling
timing
Figure 14.28 Receive Data Sampling Timing in Smart Card Interface Mode (When Clock
Frequency is 372 Times the Bit Rate)
14.7.5 Initialization
Before starting transmitting and receiving data, initialize the SCI using the following procedure.
Initialization is also necessary before switching from transmission to reception and vice versa.
1. Clear the TE and RE bits in SCR to 0.
2. Clear the error flags ORER, ERS, and PER in SSR to 0.
3. Set the GM, BLK, O/E, BCP1, BCP0, CKS1, and CKS0 bits in SMR appropriately. Also set
the PE bit to 1.
4. Set the SMIF, SDIR, and SINV bits in SCMR appropriately. When the SMIF bit is set to 1, the
TxD and RxD pins are changed from port pins to SCI pins, placing the pins into high
impedance state.
5. Set the value corresponding to the bit rate in BRR.
6. Set the CKE1 and CKE0 bits in SCR appropriately. Clear the TIE, RIE, TE, RE, MPIE, and
TEIE bits to 0 simultaneously. When the CKE0 bit is set to 1, the SCK pin is allowed to output
clock pulses.
7. Set the TIE, RIE, TE, and RE bits in SCR appropriately after waiting for at least 1 bit interval.
Setting prohibited the TE and RE bits to 1 simultaneously except for self diagnosis.
To switch from reception to transmission, first verify that reception has completed, and initialize
the SCI. At the end of initialization, RE and TE should be set to 0 and 1, respectively. Reception
completion can be verified by reading the RDRF flag or PER and ORER flags. To switch from
transmission to reception, first verify that transmission has completed, and initialize the SCI. At
Rev. 3.00, 03/04, page 410 of 830