MC68HC08GP32A Datasheet, PDF (140/258 Pages) Freescale Semiconductor, Inc – Microcontrollers

Serial Communications Interface (SCI) Module
SCIBDSRC
FROM
MOR2
CGMXCLK
BUS CLOCK
A
B
SL
X
SL = 0 => X = A
SL = 1 => X = B
INTERNAL BUS
÷4
PRE- BAUD
SCALER DIVIDER
÷ 16
SCI DATA REGISTER
SCP1
SCP0
SCR2
SCR1
SCR0
TXINV
11-BIT
TRANSMIT
SHIFT REGISTER
H876543210L
PTE0/TxD
M
PEN
PARITY
PTY
GENERATION
T8
TRANSMITTER CPU
INTERRUPT REQUEST
TRANSMITTER
CONTROL LOGIC
SCTE
SCTIE
TC
TCIE
SCTE
SCTIE
TC
TCIE
Figure 14-5. SCI Transmitter
SBK
LOOPS
ENSCI
TE
14.4.2.2 Character Transmission
During an SCI transmission, the transmit shift register shifts a character out to the PTE0/TxD pin. The SCI
data register (SCDR) is the write-only buffer between the internal data bus and the transmit shift register.
To initiate an SCI transmission:
1. Enable the SCI by writing a 1 to the enable SCI bit (ENSCI) in SCI control register 1 (SCC1).
2. Enable the transmitter by writing a 1 to the transmitter enable bit (TE) in SCI control register 2
(SCC2).
3. Clear the SCI transmitter empty bit by first reading SCI status register 1 (SCS1) and then writing
to the SCDR.
4. Repeat step 3 for each subsequent transmission.
MC68HC08GP32A • MC68HC08GP16A Data Sheet, Rev. 1.0
140
Freescale Semiconductor