Siemens ERTEC200 - Manual (Page 64)

5 General Hardware Functions
5.1 Clock Generation and Clock Supply
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
5.1.1 Clock Supply in ERTEC 200
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
Table 17: Overview of ERTEC 200 Clocks
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
Copyright © Siemens AG 2007. All rights reserved. 64 ERTEC 200 Manual
Technical data subject to change Version 1.1.0