MPC555CME Freescale Semiconductor, MPC555CME Datasheet - Page 865

• Manufacturer Part Number: MPC555CME
• Description: KIT EVALUATION FOR MPC555
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC555CME

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC555
• Data Bus Width: 32 bit
• Interface Type: RS-232
• For Use With/related Products: MPC555
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

D.19.2 Host CPU Initialization of the SIOP Function
D.19.3 SIOP Function Performance
MPC555 / MPC556
USER’S MANUAL
by the value of BIT_D. In output only mode, zero will be shifted into SIOP_DATA and
in input only mode, the data shifted out is ignored. In clock-only mode SIOP_DATA is
still shifted. Note that no ‘justifying’ of SIOP_DATA is performed by the TPU, (e.g., if
an 8-bit bi-directional transfer is made, shifting lsb first, then the bottom byte of
SIOP_DATA will be shifted out and the input data will be shifted into the upper byte of
SIOP_DATA).
The CPU initializes the SIOP function by:
The TPU then starts the data transfer, and issues an interrupt request when the trans-
fer is complete.
Once the function has been initialized, the CPU only needs to write SIOP_DATA with
the new data and issue a HSR 0b11 to initiate a new transfer. In input or clock-only
modes, just the HSR 0b11 is required.
Like all TPU functions, the performance limit of the SIOP function in a given application
is dependent to some extent on the service time (latency) associated with other active
TPU channels. This is due to the operational nature of the scheduler. Where two
channels are being used for a uni-directional system, and no other TPU channels are
active, the maximum baud rate is approximately 230 KHz at a bus speed of 16.77
MHz. A three-channel bi-directional system under the same conditions has a maxi-
mum baud rate of approximately 200 KHz. When more TPU channels are active,
these performance figures will be degraded, however, the scheduler assures that the
worst case latency in any TPU application can be closely approximated. It is recom-
mended that the guidelines given in the TPU reference manual be used along with the
information given in the SIOP state timing table to perform an analysis on any pro-
posed TPU application that appears to approach the performance limits of the TPU.
1. Disabling the channel by clearing the two channel priority bits
2. Selecting the SIOP function on the channel by writing the assigned SIOP func-
3. Writing CHAN_CONTROL in the clock channel parameter RAM
4. Writing HALF_PERIOD, BIT_D and XFER_SIZE in the clock channel parame-
5. Writing SIOP_DATA if the data output is to be used
6. Selecting the required operating mode via the two host sequence bits
7. Issuing a host service request type 0b11
8. Enabling service by assigning H, M or L priority to the clock channel via the two
tion number to the function select bits
ter RAM to determine the speed, shift direction and size of the transfer
channel priority bits
SIOP_DATA is not buffered. The CPU should only access it between
completion of one transfer and the start of the next.
TPU ROM FUNCTIONS
Rev. 15 October 2000
NOTE
MOTOROLA
D-51