NXP Semiconductors MC9S12G User Manual

Serial Communication Interface (S12SCIV5)
MC9S12G Family Reference Manual Rev.1.27
672 NXP Semiconductors
20.4.5 Transmitter
Figure 20-16. Transmitter Block Diagram
20.4.5.1 Transmitter Character Length
The SCI transmitter can accommodate either 8-bit or 9-bit data characters. The state of the M bit in SCI
control register 1 (SCICR1) determines the length of data characters. When transmitting 9-bit data, bit T8
in SCI data register high (SCIDRH) is the ninth bit (bit 8).
20.4.5.2 Character Transmission
To transmit data, the MCU writes the data bits to the SCI data registers (SCIDRH/SCIDRL), which in turn
are transferred to the transmitter shift register. The transmit shift register then shifts a frame out through
the TXD pin, after it has prefaced them with a start bit and appended them with a stop bit. The SCI data
registers (SCIDRH and SCIDRL) are the write-only buffers between the internal data bus and the transmit
shift register.
PE
PT
H876543210L
11-Bit Transmit Register Stop Start
T8
TIE
TDRE
TCIE
SBK
TC
Parity
Generation
MSB
SCI Data Registers
Load from SCIDR Shift Enable Preamble (All 1s) Break (All 0s)
Transmitter Control
M
Internal Bus
SBR12:SBR0
Baud Divider
16
Bus
Clock
TE
SCTXD
TXPOL
LOOPS
LOOP
RSRC
CONTROL
To Re ceiv e r
Transmit
Collision Detect
TDRE IRQ
TC IRQ
SCTXD
SCRXD
(From Receiver)
TCIE
BERRIF
BER IRQ
BERRM[1:0]

NXP Semiconductors MC9S12G Specifications

General

Brand	NXP Semiconductors
Model	MC9S12G
Category	Microcontrollers
Language	English