MPC555 / MPC556
TPU ROM FUNCTIONS
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
D-33
CONTROL BITS
NAME
OPTIONS
ADDRESSES
3
2
1
0
c
Channel Function Select
PPWA Function Number
0x30YY0C – 0x30YY12
(Assigned During Microcode Assembly)
1
0
c
Channel Priority
00 – Channel Disabled
0x30YY1C – 0x30YY1E
01 – Low Priority
10 – Medium Priority
11 – High Priority
1
0
c
Host Sequence Bits
00 – Accumulate 24-Bit Periods, No Links
0x30YY14 – 0x30YY16
01 – Accumulate 16-Bit Periods, Links
10 – Accumulate 24-Bit Pulse Widths,
No Links
11 – Accumulate 16-Bit Pulse Widths,
Links
1
0
c
Host Service Bits
00 – Not Used
0x30YY18 – 0x30YY1A
01 – Not Used
10 – Initialize
11 – Not Used
0
c
Interrupt Enable
0 – Channel Interrupt Not Asserted
0x30YY0A
1 – Channel Interrupt Asserted
0
c
Interrupt Status
0x30YY20
PARAMETER RAM
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0x30YYW0
START_LINK_
CHANNEL
LINK_CHANNEL
_COUNT
CHANNEL_CONTROL
0x30YYW2
MAX_COUNT
PERIOD_COUNT
0x30YYW4
LAST_ACCUM
0x30YYW6
ACCUM
0x30YYW8
ACCUM_RATE
PPWA_UB
0x30YYWA
PPWA_LW
0x30YYWC
0x30YYWE
= Written By CPU
= Written by CPU and TPU
W = Channel Number
YY = 41 for TPU_A and 44 for
TPU_B
= Written By TPU
= Unused Parameters
NOTES:
1.
The TPU does not check the value of LINK_CHANNEL_COUNT. If this parameter is NOT >0 and
≤
8,
results are unpredictible.
2.
MAX_COUNT may be written at any time by the host CPU, but if the value written is
≤
PERIOD_COUNT, a
period or pulse-width accumulation is terminated. If this happens, the number of periods over which the
accumulation is done will not correspond to MAX_COUNT.
Figure D-21 PPWA Parameters
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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