Siemens ERTEC200 User Manual

 

The clock system of the ERTEC 200 basically consists of four clock systems that are decoupled through asynchronous 
transfers. 
This includes the following clock systems: 

• 

ARM946E-S together with AHB bus, APB bus, and IRT 

• LBU 

• JTAG 

Interface 

• 

PHYs and Ethernet MACs 

 

The required clocks are generated in the ERTEC 200 by means of internal PLL and/or through direct infeed. 
The following table provides a detailed list of the clocks: 

 

MODULE 

CLOCK SOURCE 

FREQUENCY 

ARM946ES PLL 

50/100/150 

MHz 

(scalable) 

AHB/EMIF/ICU/LBU PLL 

50 

MHz 

IRTE (except MAC-MII) 

PLL 

50/100 MHz 

APB PLL  50 

MHz 

JTAG JTAG-Clock  0-10 

MHz 

MAC-MII/PHY CLKP_A 

25 

MHz 

A PLL is integrated to generate the internal clocks in the ERTEC 200. The clock supply of the PLL takes place via the 
following input pins: 

¾  25 MHz quartz at the inputs CLKP_A and CLKP_B or 
¾  25 MHz clock generator at input CLKP_A 

 
The input clock is divided down by a factor of 12.5 MHz and fed into the PLL. The PLL generates a clock of 300 MHz, 
which supplies the following clock generator. This generates all system clock required for the ERTEC 200.   
 
The following figure shows the generation of the ERTEC 200 clocks: 
 

Divider

1:2

REF_CLK

25 MHz

CONFIG1

APLL

PLL_IN
(12,5 MHz)

PLL_OUT

(300 MHz)

CONFIG4

CONFIG3

MUX

MUX

MUX

SCANMODE

CLK_ARM

CLK_100

CLK_50

HCLKEN -

Gen.

HCLKEN

(ARM9)

Lock -Timer

Power -

up

(650us)

Loc

k

CLK_IN

Enable

PLL_LOCK_STATE

BYPASS_CLK_IN

Clock

Generation

0

1

0

1

0

1

OS

C

MUX

SCAN_CLK(2:0)

2

0

1

BYPASS_CLK

100MHz

Lock 

Monitor

PHY_CLK

&

&

CLK_UART

CLKP_A

25 

MHz

CLKP_B

 

Figure 9: Clock Generation in ERTEC 200

 

  
Synchronous clocks CLK_50MHz and CLK_100MHz are used primarily in the ERTEC 200. For the ARM946E-S 
processor, the required processor clock can be set via the configuration pins CONFIG[4:3]: 

¾  CONFIG4, CONFIG3 = 00 Æ 

ARM946 processor clock is 50 MHz. 

¾  CONFIG4, CONFIG3 = 01 Æ 

ARM946 processor clock is 100 MHz. 

¾  CONFIG4, CONFIG3 = 10 Æ 

ARM946 processor clock is 150 MHz. 

¾  CONFIG4, CONFIG3 = 11 Æ 

Reserved 

 

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