
TAMC900 User Manual Issue 2.0.1
Page 29 of 71
6.2 DCM Multiply/Divide 0/1
It is possible to define sample rates for the on board ADCs that are generated by the FPGA. For this the
module provides two configurable digital clock managers (DCMs).
The sample frequency is adjusted in the way of defining a multiply and division value. The resulting fraction
is applied on a source clock which has a frequency of 50 MHz.
The values for multiplication and division are grouped into a single data word. This is due to
the physical interface of a Virtex-5 DCM.
Bit
Symbol
Description
Access
Reset
Value
15:8 MULT The selected multiplier is the assigned value plus one. Valid
range is 1 up to 31
R/W 24
7:0
DIV
The selected divider is the assigned value plus one.
Valid range is 0 up to 31
R/W 24
Table 6-2 : DCM Multiply/Divide Register (Address 0x4+ 0x4*DCM Number)
The legal value range reflect the Virtex-5 DCM specification. Do not use values other than the
allowed ones. The minimum frequency that can be set is 32 MHz. The reset value adjusts a
sample frequency of 50 MHz.