Initialization - Renesas H8S/2158 User Manual

16.7.5

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.
Do not set 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
the end of initialization, TE and RE should be set to 0 and 1, respectively. Transmission
completion can be verified by reading the TEND flag.
Section 16 Serial Communication Interface (SCI, IrDA, and CRC)
Rev. 3.00 Jan 25, 2006 page 449 of 872
REJ09B0286-0300