Electrical Characteristics

MSC8122 Quad Digital Signal Processor Data Sheet, Rev. 15

Freescale Semiconductor

19

2.5.4

Reset Timing

The MSC8122 has several inputs to the reset logic:

•

•

•

•

Software watchdog reset

•

Bus monitor reset

•

Host reset command through JTAG

All MSC8122 reset sources are fed into the reset controller, which takes different actions depending on the source of the reset.

The reset status register indicates the most recent sources to cause a reset. Table 10 describes the reset sources.

Table 9. System Clock Parameters

Characteristic

Min

Max

Unit

Phase jitter between BCLK and CLKIN

—

0.3

ns

CLKIN frequency

20

see Table 8

MHz

CLKIN slope

—3

ns

—

150

ps

CLKIN jitter spectrum

150

—

KHz

PLL input clock (after predivider)

20

100

MHz

PLL output frequency (VCO output)

•

300 MHz core

•

400 MHz core

•

500 MHz core

800

1200

1600

2000

MHz

MHz

MHz

MHz

—

200

ps

—

500

ps

Notes:

1.

Peak-to-peak.

2.

Not tested. Guaranteed by design.

Table 10. Reset Sources

Name

Direction

Description

Power-on reset

(PORESET)

Input

Initiates the power-on reset flow that resets the MSC8122 and configures various attributes of the

MSC8122. On PORESET, the entire MSC8122 device is reset. SPLL states is reset, HRESET and

SRESET are driven, the SC140 extended cores are reset, and system configuration is sampled. The

clock mode (MODCK bits), reset configuration mode, boot mode, Chip ID, and use of either a DSI 64

bits port or a System Bus 64 bits port are configured only when PORESET is asserted.

External hard

reset (HRESET)

Input/ Output

Initiates the hard reset flow that configures various attributes of the MSC8122. While HRESET is

asserted, SRESET is also asserted. HRESET is an open-drain pin. Upon hard reset, HRESET and

SRESET are driven, the SC140 extended cores are reset, and system configuration is sampled. The

most configurable features are reconfigured. These features are defined in the 32-bit hard reset

configuration word described in Hard Reset Configuration Word section of the Reset chapter in the

MSC8122 Reference Manual.

External soft reset

(SRESET)

Input/ Output

Initiates the soft reset flow. The MSC8122 detects an external assertion of SRESET only if it occurs

while the MSC8122 is not asserting reset. SRESET is an open-drain pin. Upon soft reset, SRESET is

driven, the SC140 extended cores are reset, and system configuration is maintained.

Software

watchdog reset

Internal

When the MSC8122 watchdog count reaches zero, a software watchdog reset is signalled. The

enabled software watchdog event then generates an internal hard reset sequence.

Bus monitor reset

Internal

When the MSC8122 bus monitor count reaches zero, a bus monitor hard reset is asserted. The

enabled bus monitor event then generates an internal hard reset sequence.

Host reset

command through

the TAP

Internal

When a host reset command is written through the Test Access Port (TAP), the TAP logic asserts the

soft reset signal and an internal soft reset sequence is generated.