PNX1502E Datasheet, PDF (162/819 Pages) NXP Semiconductors – Connected Media Processor

Philips Semiconductors
Volume 1 of 1
PNX15xx Series
Chapter 5: The Clock Module
The GPIO interrupt comes from the GPIO block and is the “OR” of all the FIFO and
timestamp registers. This way a GPIO pin can be monitored and when an event
occurs the interrupt to the processor awakes the system. Bit ‘0’ of the
CLK_WAKEUP_CTL enables the GPIO interrupt.
The external signal is the dedicated GPIO pin 15. This signal must be active for at
least one xtal_clk clock period. It is expected that this signal will stay active until the
CPU responds which will be several xtal clock periods. Bit ‘1’ of the
CLK_WAKEUP_CTL enables the external interrupt. GPIO[15] must be low when
entering in power down mode since the wake-up procedure is started when the
GPIO[15] pin is set to high for at least one xtal_clk clock cycle.
2.9 Clock Detection
Clock detection is required in the case of an external clock being removed or
disconnected e.g if the video cable to the set top box is suddenly removed and an
external video clock thereby stopped. this type of event is detected by the Clock
module. Also the Clock module can detect when the cable is re-connected and a
clock is present again.
These events are flagged by an interrupt which is routed to the TM3260.
The clock detection will be done on the following clocks inputs to PNX15xx Series:
• VDI_CLK1 (clk_vip)
• AI_SCK
• AO_SCK
• VDI_CLK2 (clk_fgpi)
• VDO_CLK2 (clk_fgpo)
Clock detection is done based on a 5-bit counter running at the crystal clock
frequency. The implementation detects clocks between 1 MHz and 200 MHz. It will
take up to 2 µs from when the clock is removed until the interrupt condition is
generated. A block diagram of the clock detection circuit is shown in Figure 6.
32
counter
xtal_clk
(external clock)
Toggle
Flop
en
Figure 6: Clock Detection Circuit
en
xtal_clk xtal_clk
clock_present edge
comp
detect
pls2lvl
PIO
INT
intrpt_clk
12NC 9397 750 14321
Product data sheet
Rev. 2 — 1 December 2004
© Koninklijke Philips Electronics N.V. 2002-2003-2004. All rights reserved.
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