Precautions - Epson S1C17704 Technical Manual

18.10 Precautions

• Before setting the bits listed below, make sure the transmit and receive operations are disabled (RXEN = 0).
- All bits (SSCK, STPB, PMD, PREN, and CHLN) of the UART_MOD register (0x4103)
- All bits (RBFI, TIEN, RIEN, and REIEN except RXEN) of the UART_CTL register (0x4104)
- All bits (IRMD and IRCLK[2:0]) of the UART_EXP register (0x4105)
∗ RXEN: UART Enable Bit in the UART Control (UART_CTL) Register (D0/0x4104)
• When the UART is transmitting or receiving data, do not set RXEN to 0.
• The maximum transfer rate of the UART is limited to 115200 bps. Do not set a transfer rate that exceeds the
limit.
• When the RXEN bit is set to 0 to disable transmit/receive operations, the transmit/receive data buffers are cleared
(initialized). Therefore, make sure that the buffers do not contain any data waiting for transmission or reading
before writing 0 to the RXEN bit.
• The IrDA receive detection clock must be faster than the transfer clock sclk supplied from the 8-bit timer or input
from the SCLK pin.
• The demodulator regards a low pulse of which the width is longer than two cycles of the IrDA receive detection
clock as a valid low pulse. Select an appropriate prescaler output clock as the IrDA receive detection clock so
that it will be able to detect a minimum 1.41 µs width of an input pulse.
S1C17704 TECHNICAL MANUAL
EPSON
18 UART
18-21