MC68HC812A4 Datasheet, PDF (160/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Clock Module
PRS[4:0]
PCLK
5-BIT ATD
PRESCALER
÷2
ATD CLOCK
REGISTER: SP0BR
BITS:
SPR2:SPR1:SPR0
0:0:0
÷2
0:0:1
÷2
0:1:0
÷2
0:1:1
÷2
1:0:0
÷2
1:0:1
÷2
1:1:0
÷2
1:1:1
SPI BIT RATE
SYNCHRONIZER
BKGD PIN
LOGIC
ECLK
BKGD IN
BKGD
DIRECTION
BKGD OUT
BDM BIT CLOCK
Receive: Detect falling edge; count 12 E-clocks; sample input
Transmit 1: Detect falling edge; count six E-clocks while output is
high impedance; drive out one E cycle pulse high; return output
to high impedance
Transmit 0: Detect falling edge; drive out low; count nine E-clocks;
drive out one E cycle pulse high; return output to high-impedance
Figure 10-6. Clock Chain for SPI, ATD and BDM
MC68HC812A4 — Rev. 3.0
160
Clock Module
Advance Information
MOTOROLA