Initialization - Renesas H8SX/1520 Series Hardware Manual

12.7.5

Initialization

Before 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. Set the ICR bit of the corresponding pin to 1.
3. Clear the error flags ERS, PER, and ORER in SSR to 0.
4. Set the GM, BLK, O/E, BCP1, BCP0, CKS1, and CKS0 bits in SMR appropriately. Also set
the PE bit to 1.
5. Set the SMIF, SDIR, and SINV bits in SCMR appropriately. When the DDR corresponding to
the TxD pin is cleared to 0, the TxD and RxD pins are changed from port pins to SCI pins,
placing the pins into high impedance state.
6. Set the value corresponding to the bit rate in BRR.
7. 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.
8. Set the TIE, RIE, TE, and RE bits in SCR appropriately after waiting for at least a 1-bit
interval. Setting the TE and RE bits to 1 simultaneously is prohibited except for self diagnosis.
To switch from reception to transmission, first verify that reception has completed, then 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, PER, or ORER flag. To switch from
transmission to reception, first verify that transmission has completed, then 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.
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Section 12 Serial Communication Interface (SCI)
Rev. 3.00 Mar. 14, 2006 Page 433 of 804
REJ09B0104-0300