M-Bus Protocol - Motorola MC68HC05T16 Technical Data Manual

Control register
MEN MIEN MSTR XMT
Interrupt
SCL
6
SDA
6.2

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 6-2.
MOTOROLA
6-2
Status register
MCF
ACKEB SELTED
M-Bus
interrupt
M-Bus clock
SCL
generator
control
sync logic
START, STOP START, STOP
detector and generator and
arbitration timing sync
SDA
control
Figure 6-1 M-Bus Interface Block Diagram
M-BUS SERIAL INTERFACE
Internal bus
BBSY LOST SRW MIF
RXACKB
Frequency
Address
divider
register
register
Address
comparator
TX shift RX shift
register register
TX RX
control control
MC68HC05T16
8
TPG