MC68HC908AP16CFA MOTOROLA [Motorola, Inc], MC68HC908AP16CFA Datasheet - Page 258

• Manufacturer Part Number: MC68HC908AP16CFA
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Infrared Serial Communications
14.6.2.1 Character Length
14.6.2.2 Character Transmission
Data Sheet
258
The transmitter can accommodate either 8-bit or 9-bit data. The state of
the M bit in IRSCI control register 1 (IRSCC1) determines character
length. When transmitting 9-bit data, bit T8 in IRSCI control register 3
(IRSCC3) is the ninth bit (bit 8).
During an SCI transmission, the transmit shift register shifts a character
out to the TxD pin. The IRSCI data register (IRSCDR) is the write-only
buffer between the internal data bus and the transmit shift register. To
initiate an SCI transmission:
At the start of a transmission, transmitter control logic automatically
loads the transmit shift register with a preamble of logic 1s. After the
preamble shifts out, control logic transfers the IRSCDR data into the
transmit shift register. A logic 0 start bit automatically goes into the least
significant bit position of the transmit shift register. A logic 1 stop bit goes
into the most significant bit position.
The SCI transmitter empty bit, SCTE, in IRSCS1 becomes set when the
IRSCDR transfers a byte to the transmit shift register. The SCTE bit
indicates that the IRSCDR can accept new data from the internal data
bus. If the SCI transmit interrupt enable bit, SCTIE, in IRSCC2 is also
set, the SCTE bit generates a transmitter interrupt request.
When the transmit shift register is not transmitting a character, the TxD
pin goes to the idle condition, logic 1. If at any time software clears the
ENSCI bit in IRSCI control register 1 (IRSCC1), the transmitter and
receiver relinquish control of the port pins.
1. Enable the SCI by writing a logic 1 to the enable SCI bit (ENSCI)
2. Enable the transmitter by writing a logic 1 to the transmitter enable
3. Clear the SCI transmitter empty bit by first reading IRSCI status
4. Repeat step 3 for each subsequent transmission.
Freescale Semiconductor, Inc.
For More Information On This Product,
in IRSCI control register 1 (IRSCC1).
bit (TE) in IRSCI control register 2 (IRSCC2).
register 1 (IRSCS1) and then writing to the IRSCDR.
Go to: www.freescale.com
MC68HC908AP Family — Rev. 2.5
MOTOROLA