MC68HC05BD3 Datasheet, PDF (48/112 Pages) Motorola, Inc – HCMOS microcontroller

Internal bus
Control register
Status register
MEN MIEN MSTA MTX TXAK MCF MAAS MBB MAL
SRW MIF RXAK
Interrupt
M-Bus
interrupt
Frequency
divider
register
SCL
7
SDA
SCL
control
M-Bus clock
generator
sync logic
START, STOP
detector and
arbitration
START, STOP
generator and
timing sync
TX shift
register
TX
control
SDA
control
Figure 7-1 M-Bus Interface Block Diagram
8
Address
register
Address
comparator
RX shift
register
RX
control
7.2
M-Bus Protocol
Normally, a standard communication is composed of four parts,
1) START signal,
2) slave address transmission,
3) data transfer, and
4) STOP signal.
They are described briefly in the following sections and illustrated in Figure 7-2.
MOTOROLA
7-2
M-BUS SERIAL INTERFACE
TPG
MC68HC05BD3