MC68302EH20C Freescale Semiconductor, MC68302EH20C Datasheet - Page 240

• Manufacturer Part Number: MC68302EH20C
• Description: IC MPU MULTI-PROTOCOL 132-PQFP
• Manufacturer: Freescale Semiconductor

Specifications of MC68302EH20C

• Processor Type: M683xx 32-Bit
• Speed: 20MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 132-MQFP, 132-PQFP
• Family Name: M68000
• Device Core: ColdFire
• Device Core Size: 32b
• Frequency (max): 20MHz
• Instruction Set Architecture: RISC
• Supply Voltage 1 (typ): 5V
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 132
• Package Type: PQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Lead Free Status / Rohs Status: Compliant

OFFSET + 0
OFFSET + 2
OFFSET + 4
Communications Processor (CP)
Data Length
Rx Buffer Pointer
4.5.15.8 V.110 Transmit Buffer Descriptor (Tx BD)
Data is presented to the CP for transmission on an SCC channel by arranging it in buffers
referenced by the channel's Tx BD table. The CP confirms transmission (or indicates error
conditions) using the BDs to inform the M68000 core whether the buffers have been ser-
viced. The Tx BD is shown in Figure 4-41.
OFFSET +6
The first word contains status and control bits. Bits 15–10 are prepared by the user before
transmission. Bit 1 is set by the V.110 controller after the buffer has been transmitted. Bit 15
is set by the user and cleared by the V.110 controller.
R—Ready
X—External Buffer
4-120
The data length is the number of octets that the V.110 controller has written to this BD
data buffer. It is written by the CP once as the BD is closed. The V.110 controller will write
nine bytes of data to the buffer. It will not write the all-zeros byte to the buffer.
This pointer contains the address of the associated data buffer. The buffer may reside in
either internal or external memory.
0 = This buffer is not currently ready for transmission. The user is free to manipulate
1 = The data buffer has been prepared for transmission by the user (but not yet trans-
0 = The buffer associated with this BD is in internal dual-port RAM.
1 = The buffer associated with this BD is in external memory.
this BD and its associated buffer. The V.110 controller clears this bit after the buffer
has been fully transmitted (or after an error condition is encountered).
mitted). No fields of this BD may be written by the user once this bit is set.
15
E
The actual buffer size should be greater than or equal to 10
bytes.
The Rx buffer pointer must be even, and the upper 8 bits of the
pointer must be zero for the function codes to operate correctly.
14
X
Figure 4-41. V.110 Transmit Buffer Descriptor
13
W
12
I
TX BUFFER POINTER (24-bits used, upper 8 bits must be 0)
11
L
MC68302 USER’S MANUAL
10
0
NOTE
NOTE
—
9
DATA LENGTH
—
8
—
7
—
6
—
5
—
4
—
3
—
2
MOTOROLA
UN
1
—
0