QADC64E Enhanced Mode Operation
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
14-51
14.4.7
Configuration and Control Using the IMB3 Interface
The QADC64E module communicates with other microcontroller modules via the IMB3. The QADC64E
bus interface unit (BIU) coordinates IMB3 activity with internal QADC64E bus activity. This section
describes the operation of the BIU, IMB3 read/write accesses to QADC64E memory locations, module
configuration, and general-purpose I/O operation.
14.4.7.1
QADC64E Bus Interface Unit
The BIU is designed to act as a slave device on the IMB3. The BIU has the following functions: to respond
with the appropriate bus cycle termination, and to supply IMB3 interface timing to all internal module
signals.
BIU components consist of
•
IMB3 buffers
•
Address match and module select logic
•
The BIU state machine
•
Clock prescaler logic
•
Data bus routing logic
•
Interface to the internal module data bus
NOTE
Normal accesses from the IMB3 to the QADC64E require two clocks.
However, if the CPU tries to access table locations while the QADC64E is
accessing them, the QADC64E produces IMB3 wait states. From one to
four IMB3 wait states may be inserted by the QADC64E in the process of
reading and writing.
14.4.7.2
QADC64E Bus Accessing
The QADC64E supports 8-bit, 16-bit, and 32-bit data transfers, at even and odd addresses. Coherency of
results read (ensuring that all results read were taken consecutively in one scan) is not guaranteed. For
example, if a read of two consecutive 16-bit locations in a result area is made, the QADC64E could change
one 16-bit location in the result area between the bus cycles. There is no holding register for the second
16-bit location. All read and write accesses that require more than one 16-bit access to complete occur as
two or more independent bus cycles. Depending on bus master protocol, these accesses could include
misaligned and 32-bit accesses.
shows the three bus cycles which are implemented by the QADC64E. The following
paragraphs describe how the three types of accesses are used, including misaligned 16-bit and 32-bit
accesses.
Summary of Contents for MPC561
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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...
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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...