MC145572 Datasheet, PDF (77/264 Pages) Freescale Semiconductor, Inc – ISDN U-INTERFACE TRANSCEIVER

5.3.1
Freescale Semiconductor, Inc.
SCP Mode
The MC145572 is equipped with an industry standard SCP interface. The SCP is used by an external
controller, such as an M68HC05 family microcontroller, MC145488 Dual Data Link Controller, or
MC68302 Integrated Multiprotocol Processor, to communicate with the U–interface transceiver.
The SCP is a full–duplex four–wire interface with control and status information passed to and from
the U–interface transceiver. The SCP interface consists of a transmit output, a receive input, a data
clock, and an enable signal. These device pins are known as SCPTx, SCPRx, SCPCLK, and SCPEN,
respectively. The SCP Clock determines the rate of exchange of data in both the transmit and receive
directions, and the SCP Enable signal governs when this exchange is to take place. The four–wire
SCP interface is supplemented with an interrupt request line, IRQ, for external microcontroller notifi-
cation of an event requiring service.
The operation and configuration of the U–interface transceiver is controlled by setting the state of
the control registers within the U–interface transceiver and monitoring the status registers. The control,
status, and M channel data registers reside in six 4–bit wide nibble registers, one 12–bit wide nibble
register, and twenty–nine 8–bit wide byte registers. A complete register map and detailed register
descriptions can be found in Chapter 4. Figure 5–2 shows pin configurations to operate MC145572
in IDL2 mode using the SCP for access to the register set. See Chapter 10 for the SCP timing
diagrams.
+5V
MC145572FN
100 kΩ
0.1 µF
20.48 MHz
8 kHz REFERENCE
17
IRQ
21
SCPEN
20
SCPCLK
18
SCPRx
19
SCPTx
34
4.096 CLKOUT
35
15.36 CLKOUT
38
BUFXTAL
39
DCHCLK
40
41
25
DCHin
DCHout
SFAR
26
SFAX/TxSFS
8
Vref P
7
Vref N
33
XTALin
32
XTALout
42
FREQREF
CAP3V ¹
VSS
22
VDD
44
VSS
2
VDDTx
11
VSSTx
10
VDDRx
3
VSSRx
4
VDDI/O
24
VSSI/O
23
VDDI/O
37
VSSI/O
36
RESET ¹⁴
NT/LT ¹⁵
MCU/GCI ⁴³
PAR/SER ¹³
M/S ¹⁶
FSR ²⁷
FSX ²⁸
DCL ³¹
Dout
Din
TxP
30
29
9
TxN ¹²
RxP ⁵
RxN ⁶
0.1 µF
+5V
0 V/+ 5 V
+5V
8 kHz
8 kHz
256 kHz . . . 4096 kHz
COUPLING
T
CIRCUIT
R
NOTE: In LT mode, the 100 kΩ resistor on SFAX/TxSFS is required when none of these pin functions is enabled.
Figure 5–2. MCU Mode with SCP Configuration
MOTOROLA
For More InforMmCa1t4io55n7O2 n This Product,
5–5
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