Data Transmission And Reception - Hitachi SH7709S Hardware Manual

15.3.6

Data Transmission and Reception

Initialization: Initialize the SCI using the following procedure before sending or receiving data.
Initialization is also required for switching from transmit mode to receive mode or from receive
mode to transmit mode. Figure 15.5 shows a flowchart of the initialization process.
1. Clear TE and RE in the serial control register (SCSCR) to 0.
2. Clear error flags FER/ERS, PER, and ORER to 0 in the serial status register (SCSSR).
3. Set the C/A bit, parity bit (O/E bit), and baud rate generator select bits (CKS1 and CKS0 bits)
in the serial mode register (SCSMR). At this time also clear the CHR and MP bits to 0 and set
the STOP and PE bits to 1.
4. Set the SMIF, SDIR, and SINV bits in the smart card mode register (SCSCMR). When the
SMIF bit is set to 1, the TxD and RxD pins both switch from ports to SCI pins and become
high-impedance.
5. Set the value corresponding to the bit rate in the bit rate register (SCBRR).
6. Set the clock source select bits (CKE1 and CKE0 bits) in the serial control register (SCSCR).
Clear the TIE, RIE, TE, RE, MPIE, and TEIE bits to 0. When the CKE0 bit is set to 1, a clock
is output from the SCK pin.
7. After waiting at least 1 bit, set the TIE, RIE, TE, and RE bits in SCSCR. Do not set the TE and
RE bits simultaneously unless performing auto-diagnosis.
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