Motorola MC68HC05T16 Technical Data Manual page 39

1) An arbitration lost which is signified by the Arbitration Lost flag, ALOST of
M-Bus Status Register.
2) Addressed as slave which is indicated by the master addressed as slave
flag, SELTED of M-Bus Status Register.
3) Completed transmission or reception of one byte of data. It depends on the
original mode of the M-Bus interface which is determined by the
Transmit/Receive flag, XMT of M-Bus Control Register.
M-Bus Status Register
MCF - Data Transfer Complete Flag
1 (set) – A byte transfer has been completed.
0 (clear) – A byte is being transfer.
SELTED - Addressed as Slave
1 (set) – Currently addressed as a slave.
0 (clear) – Currently not addressed.
When its own specific address (M-Bus Address register) matches the calling address, this bit is
set. An interrupt is generated if the MIEN bit is set. Then CPU needs to check the SRW bit and set
its XMT bit accordingly. Writing to the M-Bus Control register clears this bit.
ALOST - Arbitration Lost
This arbitration lost bit is set by hardware when the M-bus master loses arbitration during a master
transmission mode. This bit must be cleared by software.
On entering the interrupt service routine, the M-Bus interrupt flag, MIF of M-Bus Status Register
must be cleared by software.
The interrupt service routine address is specified by the contents of memory location $FFF4 and
$FFF5. Reset disables the whole M-Bus block by clearing the M-Bus Control Register.
Refer to Section 6 for detailed description of M-Bus.
MC68HC05T16
Address bit 7 bit 6 bit 5
$3A MCF SELTED BBSY ALOST
RESETS AND INTERRUPTS
bit 4 bit 3 bit 2 bit 1
SRW MIF
4
State
bit 0
on reset
1000 0001
RXACKB
TPG
MOTOROLA
4-9