Time Processor Unit 3
MPC561/MPC563 Reference Manual, Rev. 1.2
19-4
Freescale Semiconductor
time (latency) determines TPU3 performance in a given application. Latency can be closely estimated. For
more information, refer to the
TPU Reference Manual
(TPURM/AD).
19.3.2
Channel Orthogonality
Most timer systems are limited by the fixed number of functions assigned to each pin. All TPU3 channels
contain identical hardware and are functionally equivalent in operation, so that any channel can be
configured to perform any time function. Any function can operate on the calling channel, and, under
program control, on another channel determined by the program or by a parameter. The user controls the
combination of time functions.
19.3.3
Interchannel Communication
The autonomy of the TPU3 is enhanced by the ability of a channel to affect the operation of one or more
other channels without CPU intervention. Interchannel communication can be accomplished by issuing a
link service request to another channel, by controlling another channel directly, or by accessing the
parameter RAM of another channel.
19.3.4
Programmable Channel Service Priority
The TPU3 provides a programmable service priority level to each channel. Three priority levels are
available. When more than one channel of a given priority requests service at the same time, arbitration is
accomplished according to channel number. To prevent a single high-priority channel from permanently
blocking other functions, other service requests of the same priority are performed in channel order after
the lowest-numbered, highest-priority channel is serviced (i.e. round-robin).
19.3.5
Coherency
For data to be coherent, all available portions of the data must be identical in age, or must be logically
related. As an example, consider a 32-bit counter value that is read and written as two 16-bit words. The
32-bit value is read-coherent only if both 16-bit portions are updated at the same time, and write-coherent
only if both portions take effect at the same time. Parameter RAM hardware supports coherent access of
two adjacent 16-bit parameters. The host CPU must use a long-word operation to guarantee coherency.
19.3.6
Emulation Support
Although factory-programmed time functions can perform a wide variety of control tasks, they may not
be ideal for all applications. The TPU3 provides emulation capability that allows the development of new
time functions. Emulation mode is entered by setting the EMU bit in TPUMCR. In emulation mode, an
auxiliary bus connection is made between the DPTRAM and the TPU3, and access to DPTRAM via the
intermodule bus is disabled. A 9-bit address bus, a 32-bit data bus, and control lines transfer information
between the modules. To ensure exact emulation, DPTRAM module access timing remains consistent with
access timing of the TPU microcode ROM control store.
To support changing TPU application requirements, Freescale has established a TPU function library. The
function library is a collection of TPU functions written for easy assembly in combination with each other
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...