MC68HC05BD3 Datasheet, PDF (56/112 Pages) Motorola, Inc – HCMOS microcontroller

Clear MIF
Y
N
Master Mode?
TX
RX
TX/RX?
Last byte Y
transmitted?
N
Last byte to ^Y
be read?
N
Generate
STOP
signal
Y
MAAS = 1?
N _Arbitration
Lost?
Y
Clear MAL
N
7
RXAK = 0?
Y
Write to MDR
Last 2nd N
byte to read?
Y
TXAK = 1
N
RX
TX/RX?
TX
ACK from N
receiver?
N
MAAS = 1?
Y
N
SRW = 1?
Y
Generate
STOP
signal
Read from MDR
Y
Write to MDR
Set RX mode
Dummy read MDR
Set TX mode
Write to MDR
RTI
Figure 7-4 Flowchart of M-Bus Interrupt Routine
MOTOROLA
7-10
M-BUS SERIAL INTERFACE
TPG
MC68HC05BD3