
MOTOROLA
12-10
CONFIGURABLE TIMER MODULE 7
MC68HC16R1/916R1
USER’S MANUAL
12.7.6 MCSM Interrupts
The MCSM can optionally request an interrupt when its counter overflows and the
COF bit in MCSMSIC is set. To enable interrupts, set the IL[2:0] field in the MCSMSIC
to a non-zero value. The CTM7 compares the CPU16 IP mask value to the priority of
the requested interrupt designated by IL[2:0] to determine whether it should contend
for arbitration priority. During arbitration, the BIUSM provides the arbitration value
specified by IARB[2:0] in BIUMCR and IARB3 in MCSMSIC. If the CTM7 wins arbitra-
tion, it responds with a vector number generated by concatenating VECT[7:6] in
BIUMCR and the six low-order bits specified by the number of the submodule request-
ing service. Thus, for MCSM12 in CTM7, six low-order bits would be 12 in decimal, or
%001100 in binary.
12.7.7 MCSM Registers
The MCSM contains a status/interrupt/control register, a counter, and a modulus latch.
All unused bits and reserved address locations return zero when read. Writes to un-
used bits and reserved address locations have no effect. The CTM7 contains three
MCSMs, each with its own set of registers. Refer to
D.7.6 MCSM Status/Interrupt/
Control Registers
,
D.7.7 MCSM Counter Registers
, and
D.7.8 MCSM Modulus
Latch Registers
for information concerning MCSM register and bit descriptions.
12.8 Single Action Submodule (SASM)
The single action submodule (SASM) provides two identical channels, each having its
own input/output pin, but sharing the same interrupt logic, priority level, and arbitration
number. Each channel can be configured independently to perform either input cap-
ture or output compare.
Table 12-2
shows the different operational modes.
NOTE
All of the functions associated with one pin are called a SASM
channel.
NOTES:
1. When a channel is operating in IC mode, the IN bit in the SIC register reflects the logic
state of the corresponding input pin (after being Schmitt triggered and synchronized).
2. When a channel is operating in OC, OCT, or OP mode, the IN bit in the SIC register
reflects the logic state of the output of the output flip-flop.
Table 12-2 SASM Operational Modes
Mode
Function
IC
1
Input capture either on a rising or falling edge or as a read-only input port
OC
2
Output compare
OCT
2
Output compare and toggle
OP
2
Output port