
CTM
REFERENCE
MOTOROLA
1-3
FUNCTIONAL OVERVIEW
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1
buses can be connected together (as shown by the dotted lines in Figure 1-1) to form two time
base buses TBBA (TBB1/TBB4) and TBBB (TBB2/TBB3). The time base buses are each 16-bits
wide and are used to transfer timing information from counters to action submodules. Each CTM
submodule can either be a clock source module (and drive one or two of the time base buses) or
an action submodule (and read and react to the timing information on the time base buses).
Every CTM module implementation must include at least a BIUSM and some form of clock
submodule. All other submodules are optional and would be selected from a library of CTM
submodules at the design stage, as required by the user to meet the needs of his application.
1.3
Byte/word/long word accesses
All CTM registers and data buses are 16 bits wide. Consequently, 16-bit (word) accesses are the
normal case. 8-bit and 32-bit accesses are also permitted; however, as there is no pipelining in the
CTM, 8-bit coherency is not supported.
1.3.1
8-bit (byte) accesses
8-bit accesses are illustrated in Figure 1-2 for even addresses and Figure 1-3 for odd addresses.
1.3.2
16-bit (word) aligned accesses
16-bit aligned access is the normal case and such accesses of counter or action submodule
registers is coherent. This is illustrated in Figure 1-4.
Figure 1-2
8-bit (byte) access (even addresses)
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CTMregister
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