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Parallel Interface Port (PIP)
MC68360 USER’S MANUAL
Certain parameter RAM values above (marked in bold face) need to be initialized by the
user before the PIP is enabled; the others are initialized/written by the CP. Once initialized,
most parameter RAM values will not need to be accessed in user software since most of the
activity is centered around the transmit buffer descriptors, not the parameter RAM.
7.13.8.14 BUFFER DESCRIPTOR TABLE POINTER (RBASE). The RBASE entry defines
the starting location in the dual-port RAM for the PIP receiver’s set of buffer descriptors. This
provides a great deal of flexibility in how BDs are partitioned. By programming the RBASE
entry and by setting the "wrap" bit in the last BD, the user may select how many BDs to allo-
cate for the receive function. The user must initialize RBASE before enabling the channel.
NOTE
.RBASE should contain a value that is divisible by 8.
7.13.8.15 CENTRONICS FUNCTION CODE REGISTER (CFCR). The FC entry contains
the value that the user would like to appear on the function code pins (FC3-0) when the
associated SDMA channel accesses memory. It also controls the byte ordering convention
to be used in the transfers.
PIP Base+12
R_CNT
Word
Rx Internal Byte Count
PIP Base+14
RTEMP
Long
Rx Temp
PIP Base+18
Res
Word
Reserved
PIP Base+1C
Res
Word
Reserved
PIP Base+20
Res
Word
Reserved
PIP Base+22
Res
Word
Reserved
PIP Base+24
Res
Long
Reserved
PIP Base+28
MAX_SL
Word
Maximum Silence period
PIP Base+2a
SL_CNT
Word
Silence counter
PIP Base+2c
CHARCTER1
Word
CONTROL character 1
PIP Base+2E
CHARCTER2
Word
CONTROL character 2
PIP Base+30
CHARCTER3
Word
CONTROL character 3
PIP Base+32
CHARCTER4
Word
CONTROL character 4
PIP Base+34
CHARCTER5
Word
CONTROL character 5
PIP Base+36
CHARCTER6
Word
CONTROL character 6
PIP Base+38
CHARCTER7
Word
CONTROL character 7
PIP Base+3A
CHARCTER8
Word
CONTROL character 8
PIP Base+3C
RCCM
Word
Receive Control Character Mask
PIP Base+3E
RCCR
Word
Receive Character Control Register
Table 7-18. Centronics Receiver Parameter RAM
Address
Name
Width
Description
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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