Owner manual

VM162/VM172 Chapter 4 Programming
Page 4- 4
© PEP Modular Computers
July 19, 1997
4.2 Initializing the 68EN360
Many components of the VM62(A) / VM42(A) are controlled by the MC68EN360. Due to this fact, this
chip requires a special initialization sequence before any other software can be started.
The following list describes how the initialization must be performed on the VM62(A) / VM42(A).
Note: The order of the initialization listed below must not be changed, otherwise erratic behaviour of
the board may result.
1) Set DPRBASE to 0x000000 0x7000001.L -> MBAR (in CPU space!)
Example
move.l #7,d1 select CPU space
move.l #$7000001,d0 value to write to MBAR
movec d1,dfc select CPU space
moves.l d0,MBAR set MBAR
2) Clear reset status register 0xFF.B -> RSR
3) Set system protection register
• bus monitor enabled, 128 system clocks timeout 0x7.B -> SYPCR
4) Set module configuration register
• bus request MC68040 arbitration ID: 3
• arbitration synchronous timing mode
• bus clear out arbitration ID: 3
• SIM60 registers are Supervisor Data
• BusClear in arbitration ID: 3
• interrupt arbitration: 3 0x60008CB3.L -> MCR
5) Set PLL enabled and lock access 0xC000.W -> PLLCR
6) Lock access to clock divider control register 0x8000.W -> CDVCR
7) Configure CLK lines
• COM2 to full strength
• COM1 disabled
• register access locked 0x83.B -> CLKOCR