MC68HC908GZ8 Datasheet, PDF (224/344 Pages) Motorola, Inc – Microcontrollers

Enhanced Serial Communications Interface (ESCI) Module
INTERNAL BUS
÷4
SCP1
SCP0
SCR1
SCR2
SCR0
PRE-
BAUD
SCALER DIVIDER
÷ 16
TXINV
ESCI DATA REGISTER
11-BIT
TRANSMIT
SHIFT REGISTER
H876543210L
SCI_TxD
PDS2
PDS1
PDS0
PSSB4
PSSB3
PSSB2
PSSB1
PSSB0
M
PEN
PARITY
PTY
GENERATION
T8
TRANSMITTER
CONTROL LOGIC
SCTE
SCTIE
TC
TCIE
SCTE
SCTIE
TC
TCIE
SBK
LOOPS
ENSCI
TE
LINT
Figure 19-4. ESCI Transmitter
To initiate an ESCI transmission:
1. Enable the ESCI by writing a logic 1 to the enable ESCI bit (ENSCI) in ESCI
control register 1 (SCC1).
2. Enable the transmitter by writing a logic 1 to the transmitter enable bit (TE)
in ESCI control register 2 (SCC2).
3. Clear the ESCI transmitter empty bit (SCTE) by first reading ESCI status
register 1 (SCS1) and then writing to the SCDR. For 9-bit data, also write the
T8 bit in SCC3.
4. Repeat step 3 for each subsequent 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 SCDR data into the transmit shift register. A logic 0 start
Data Sheet
224
Enhanced Serial Communications Interface (ESCI) Module
MC68HC908GZ8
Freescale Semiconductor