Theory of Operation: Controller 3-39
3.2.3 Clock Sources
The VOCON board contains multiple crystal clock sources. These sources are active upon power-
up. Secondary clock frequencies are derived on the VOCON board from these crystal sources. In
addition to the crystal frequencies, the VOCON receives a 16.8 MHz sine wave from the RF board,
which is shaped into square wave and fed to the OMAP timer input. Screen shots and test points for
these clock signals are shown in Chapter 6.
Figure 3-29. VOCON Clock Architecture
Table 3-6. VOCON Clock Distribution
Clock
Source
Frequency Type Description Clock
Recipent
Suggested
Probe Points
Y6501 24.576 MHz Crystal
Oscillator
MAKO 24 MHz & tapped into CPLD U6501, U6101 R6578, R6572
Y6502 32.768 kHz Crystal
Oscillator
MAKO RTC U6501 C6541
Y6601 12 MHz Crystal
Oscillator
OMAP CPU Clock U6302 C6601
U6302 96 MHz OMAP GPIO DDR Clocks (Complementary signals) U6301 TP6307 &
TP6308
U6101 4 MHz CPLD GPIO MACE Clock U5003 R6113
U6101 32.768 kHz CPLD GPIO GPS RTC clock U2206
(Expansion
Board)
R6115
Y701
(RF
board)
16.8 MHz Crystal
Oscillator
RF Freq. synth. IC (Abacus) TCXO U6302 R6218
GPS
26 MHz
OMAP
MAKO
CPLD
DDR
SQUARING
TRIDENT
RF BOARD
VOCON
EXPANSION
24.576 MHz
32.768 kHz
12 MHz
4.096 MHz
32.768 kHz
16.8 MHz
96 MHz
MACE
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