13-6
MCF5272 User’s Manual
GCI/IDL Block
Because the reception and transmission of information on the GCI/IDL interface is
deterministic, a common interrupt is generated at the 2-KHz rate. It is expected that a
common interrupt service routine services the transmit and receive registers.
After reset, the B- and D-channel shift registers and shadow registers are initialized to all
ones.
Figure 13-5. GCI/IDL B Data Transmit Register Multiplexing
13.2.3 GCI/IDL B- and D-Channel Bit Alignment
Unencoded voice is normally presented on the physical line most significant bit first (left
aligned). See the MC145484 data sheet for an example. Accordingly, the MCF5272
normally assumes incoming data are left-aligned.
However, this convention is reversed when the data stream is HDLC (high-level data link
control) encoded. HDLC-stuffing and unstuffing are done by counting bits from the lsb. The
look-up table in the software HDLC on this device transmits the lsb first.
13.2.3.1 B-Channel Unencoded Data
Because unencoded voice data appears on the physical interface most significant bit (msb)
first, the msb is left aligned in the transmit and receive shift register; that is, the first bit of
B-channel received data is aligned in the msb position as shown in Figure 13-6.
The CPU uses longword (32-bit) registers (like P0B1RR) to communicate B-channel data
to/from the PLIC. These registers are loaded by concatenating four of the 8-bit/8-KHz
frames. The four frames are aligned sequentially as shown in Figure 13-6, with the first
frame in the most significant byte (MSB) position, and the fourth frame taking the least
significant byte (LSB) position. See Section
13.5.1, “B1 Data Receive Registers
13.5.5, “B2 Data Transmit Registers
8 bits
MUX
Internal Bus
8-KHz Rate
Shift Register
2-KHz transfer and interrupt
Shadow Register
8 bits
8 bits
8 bits
8 bits
START
END
32 bits
32
32
B1, B2 Transmit
Data Register
Summary of Contents for DigitalDNA ColdFire MCF5272
Page 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Page 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Page 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Page 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Page 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Page 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Page 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Page 338: ...13 44 MCF5272 User s Manual Application Examples ...
Page 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Page 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Page 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Page 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...