Nortel Networks MSC8101 ADS user manual Local Interrupter, Clock Generator

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

Functional Description

5•1•5 MSC8101 Internal Hard Reset Sources

The MSC8101 has internal sources which generate Hard / Soft Resets. Among these sources are:

1)Loss of Lock Reset (Hard)

2)S/W Watch Dog Reset (Hard)

3)Bus Monitor (Hard)

4)JTAG/ONCE Reset (Hard)

In general, the MSC8101 asserts a reset line HARD or SOFT for a period 512 clock cycles after the reset source has been identified. A hard reset sequence is followed by a soft reset sequence that released three bus clocks later than hard reset is negated.

5•2 Local Interrupter

There are external interrupts which are applied to the MSC8101ADS via its interrupt controller:

1)ABORT (NMI)

2)ATM UNI interrupt

5•2•1 ABORT Interrupt

The ABORT (NMI), is generated by a push-button. When this button is depressed, the IRQ0 input to the MSC8101 is asserted. The purpose of this type of interrupt, is to support the use of resident debugger if any is made available to the MSC8101ADS. To support external (off-board) generation of an NMI, the IRQ0 line, is driven by an open-drain gate. This allows for an external h/w, to also drive this line. If an external h/w indeed does so, it is compulsory that IRQ0 is driven by an open- drain (or open-collector) gate.

5•2•2 ATM UNI Interrupt

To support ATM UNI (User Network I/F) event report by means of interrupt, the interrupt output of the UNI (INTB) is connected to IRQ6 line of the MSC8101.

Since INTB of the UNI is an open-drain output, it is possible to connect additional (off-board) inter- rupt requesters on the same IRQ6, provided that they drive IRQ6 with open-drain gate as well.

5•2•3 QFALC Interrupt

Interrupt of T1/E1 Frame are served by IRQ7. The QFALC has an open-drain output, therefore it is possible to connect additional (off-board) interrupt requesters on the IRQ7 line, the same way as IRQ6.

5•3 Clock Generator

The MSC8101 requires a single clock source for the main clock oscillator. Use is done with 25MHz (16.38MHz) 3.3V clock generator mounted on the 14-pin DIP socket for simpler changing. Also clock may be provided from external clock generator (reference) via SMB-connector. All MSC8101 PPC bus timings are referenced to the clock output of the DSP. The CLKOUT is connected to a low inter-skew buffer to split the load between all various clock consumers on the board. One of the channel intends for the MSC8101 DLL input to eliminate buffer and path propagation delay.

Special care is taken to isolate and terminate the clock route between the on-board devices and the MSC8101, this to provide a "clean" clock for proper operation. The main clock scheme is shown in figure below:

42 MSC8101ADS RevB User’s Manual MOTOROLA

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