MC68F375
CONFIGURABLE TIMER MODULE (CTM9)
MOTOROLA
REFERENCE MANUAL
Rev. 25 June 03
13-4
13.1.2 CTM9 Pins and Naming Convention
The CTM9 uses 17 pins. The usage of these pins is shown in Figure 13-1 and Table 13-1. The CTM9 digital input and output pin names are composed of three sections
according to the following convention:
<submodule prefix><submodule number><submodule suffix (optional)>
The pin prefix and suffix for the different submodules used in the CTM9 are as follows:
FCSM pin name:
<submodule prefix>: “CTF”
<submodule suffix>: none
For example an FCSM placed as submodule number n would have its corre-
sponding input clock pin called: CTFn
MCSM pin name:
<submodule prefix>: “CTM”
<submodule suffix>: C for the Clock pin
<submodule suffix>: L for the Load pin
For example an MCSM placed as submodule number n would have its corre-
sponding input clock pin named: CTMnC and its input load pin called CTMnL.
SASM pin name:
<submodule prefix>: “CTS”
<submodule suffix>: A for channel A I/O
<submodule suffix>: B for channel B I/O
For example an SASM placed as submodule number n would have its corre-
sponding channel A I/O pin named: CTSnA and its channel B I/O pin called:
CTSnB.
DASM pin name:
<submodule prefix>: “CTD”
<submodule suffix>: none
For example a DASM placed as submodule number n would have its correspond-
ing I/O pin called: CTDn
PWMSM pin name:
<submodule prefix>: “CPWM”
<submodule suffix>: none
For example a PWMSM placed as submodule number n would have its corre-
sponding output pin called: CPWMn
In the CTM9, some pins are multiplexed between submodules. Table 13-1 shows
using the same pin names for the inputs or outputs which are connected together.
13.2 Free Running Counter Submodule (FCSM)
The free-running counter submodule (FCSM) has a 16-bit up counter with an associ-
ated clock source selector, selectable time-base bus drivers, software writable control
registers, software readable status bits, and interrupt logic. When the 16-bit up counter
overflows from 0xFFFF to 0x0000, an optional overflow interrupt is available to the
software. The current state of the 16-bit counter is the primary output of the counter
submodules. The software selects which, if any, time-base bus is to be driven by the
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