
NXP Semiconductors
PNX15xx/952x Series
Volume 1 of 1
Chapter 5: The Clock Module
PNX15XX_PNX952X_SER_N_4
NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 4.0 — 03 December 2007
5-165
2.5 Power-up and Reset sequence
On power-up, the Clock module outputs the default 27 MHz clocks to all the
PNX15xx/952x Series modules. Once the Reset module has released the internal
module resets, the boot-up sequence executed by the Boot module starts off the 27
MHz clock. At some point in the boot up sequence, the Boot module switches
TM3260 and the DDR clocks to the associated PLLs, PLL0 and PLL2. The Clock
module keeps feeding the other PNX15xx/952x Series modules with the initial 27
MHz clock until the software decides otherwise.
2.6 Clock Stretching
The TM3260 clock, clk_tm, can be paused or stretched for one clock pulse. A counter
counts to a pre-programmed value. When this value is reached the clock gating circuit
will turn off the TM3260 clock for one clock period. Then the TM3260 clock is turned
back on.
The procedure to operate the clock stretching circuit is to program the
CLK_STRETCHER_CTL MMIO register to the value desired between clock
stretches. For example a value of 3 turns off the clock every 3 clocks as pictured in
A Write to the CLK_STRETCHER_CTL register acts as the enable for the feature.
clk_qvcp
CLK_QVCP_OUT_CTL
XIO_ACK
clk_qvcp_pix
CLK_QVCP_PIX_CTL
XIO_D[8]
clk_qvcp_proc
CLK_QVCP_PROC_CTL
XIO_D[9]
clk_lcd_tstamp
CLK_LCD_TSTAMP_CTL
XIO_D[10]
clk_vip
CLK_VIP_CTL
XIO_D[11]
clk_vld
CLK_VLD_CTL
XIO_D[12]
ai_osclk
AI_OSCLK_CTL
XIO_D[13]
ao_osclk
AO_OSCLK_CTL
XIO_D[14]
clk_spdo
CLK_SPDO_CTL
XIO_D[15]
clk_spdi
CLK_SPDI_CTL
LAN_TXD[0]
clk_gpio_q4
CLK_GPIO_Q4_CTL
LAN_TXD[1]
clk_gpio_q5
CLK_GPIO_Q5_CTL
LAN_TXD[2]
clk_gpio_q6_12
CLK_GPIO_Q6_12_CTL
LAN_TXD[3]
clk_gpio_13
CLK_GPIO_13_CTL
LAN_RXD[0]
clk_gpio_14
CLK_GPIO_14_CTL
LAN_RXD[1]
clk_fgpo
CLK_FGPO_CTL
LAN_RXD[2]
clk_fgpi
CLK_FGPI_CTL
LAN_RXD[3]
Table 8: Bypass Clock Sources
Clocks from Clock
Module
Bypass Control Register
GPIO pin
Assignment