PLL0_SYSCLK2
LPSC
uPP
PLL0_SYSCLK2
PLL1_SYSCLK2
0
1
1
0
CFGCHIP3[UPP_TX_CLKSRC]
CFGCHIP3[ASYNC3_CLKSRC]
Module
Clock
Transmit
Clock
UPP_2xTXCLK pin
Peripheral Clocking
127
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Device Clocking
6.3.5 uPP Clocking
displays the clock connections for the uPP module. The uPP subsystem requires a module
clock to drive its internal logic and a transmit clock to drive I/O signals in transmit mode. The module clock
is always sourced by PLL0_SYSCLK2. The transmit clock is sourced by three different clocks:
PLL0_SYSCLK2 (default), PLL1_SYSCLK2, or the externally driven UPP_2xTXCLK pin. The transmit
clock source is selected by the UPP_TX_CLKSRC and ASYNC3_CLKSRC bits in the chip configuration 3
register (CFGCHIP3) of the System Configuration Module.
lists the register values that select
each of the three possible clock sources.
Regardless of the source, the uPP transmit clock speed cannot exceed the uPP module clock speed. The
module clock speed must be greater than or equal to the transmit clock speed.
Figure 6-6. uPP Clocking Diagram
Table 6-8. uPP Transmit Clock Selection
CFGCHIP3.UPP_TX_CLKSRC bit
CFGCHIP3.ASYNC3_CLKSRC bit
uPP Transmit Clock Source
0
0
PLL0_SYSCLK2
0
1
PLL1_SYSCLK2
1
x
UPP_2xTXCLK pin