44
MVME4100 Single Board Computer Programmer’s Reference (6806800H19D)
Register Descriptions
Register Descriptions
3.1.25
External Timer Registers
The MVME4100 provides a set of tick timer registers for access to the four external timers
implemented in the timers/registers PLD. Note that these registers are 32-bit registers and
are not byte writable. The following sections describe the external timer prescaler and
control registers.
3.1.25.1 Prescaler Register
The Prescaler Adjust value is determined by this formula:
Prescaler Adjust=256-(CLKIN/CLKOUT)
Where CLKIN is the input clock source in MHz and CLKOUT is the desired output clock
reference in MHz.
The prescaler provides the clock required by each of the four timers. The tick timers require
a 1 MHz clock input. The input clock to the prescaler is 25 MHz. The default value is set for
$E7 which gives a 1 MHz reference clock for a 25 MHz input clock source.
Table 3-28
Prescaler Register
REG
Prescaler Register - 0xF202 0000 (8 bits of a 32-bit register)
BIT
7
6
5
4
3
2
1
0
Field
Prescaler Adjust
OPER
R/W
RESET
$E7
Summary of Contents for MVME4100
Page 1: ...MVME4100 Single Board Computer Programmer s Reference P N 6806800H19D September 2019 ...
Page 6: ...6 MVME4100 Single Board Computer Programmer s Reference 6806800H19D Table of Contents ...
Page 8: ...8 MVME4100 Single Board Computer Programmer s Reference 6806800H19D Table of Contents ...
Page 83: ...1 ...
