Motorola MVME1X7P - Manual (Page 218)

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PCCchip2
3
Tick Timer 2 Counter
The Tick Timer 2 Counter is a 32-bit read/write register located at address
$FFF42010. When enabled, it increments every microsecond. Software
may read or write the counter at any time.
Prescaler Count Register
The Prescaler Count Register is an 8-bit counter used to generate the 1
MHz clock for the two tick timers. This register is a read-only register
located at address $FFF42014. It increments to $FF at the BCLK
frequency, then it is loaded from the Prescaler Clock Adjust Register.
Prescaler Clock Adjust Register
Note The PCCchip2 runs at half the MPU speed on the MVME177P.
For example, an MVME177P with a 50 MHz MPU will run the
PCCchip2 at 25 MHz.
The Prescaler Clock Adjust Register is an 8-bit read/write register located
at address $FFF42015. It is required to adjust the prescaler so that it
maintains a 1 MHz clock source for the tick timers, regardless of what
ADR/SIZ $FFF42010 (32 bits)
BIT 31 . . . 0
NAME Tick Timer 2 Counter
OPER R/W
RESET X
ADR/SIZ $FFF42014 (8 bits)
BIT 31 . . . 24
NAME Prescaler Count
OPER R/W
RESET X