AN2007 Motorola / Freescale Semiconductor, AN2007 Datasheet - Page 9

• Manufacturer Part Number: AN2007
• Description: Evaluating ColdFire in a 68K Target System: MC68340 Gateway Reference Design
• Manufacturer: Motorola / Freescale Semiconductor

Creating a Gateway reference board for the MC68340 to the MCF5206e microprocessor would require a
3.3V supply to the MCF5206e. The easiest way to achieve this would be to have the 5V supplied from the
target hardware and have it DC to DC regulated to 3.3V on the Gateway module.
After removing the circuitry for the additional port and the DMA controller from the MC68340-MCF5206
Gateway board, the PAL equations would have to be modified for the MC68340-MCF5206e Gateway board.
Again, the modifications involve removing code rather than adding it. The following equations should be
removed from PAL U8 due to redundancy:
BR_DMA
And the following equations should be modified:
BG_340
To be:
BG_340
And,
BG
To be:
BG
The remaining schematics and logic do not need further modification for the creation of an
MC68340-MCF5206e Gateway board.
It is important to note that MCF5206e operates at a maximum frequency of 54MHz. It may be necessary to
modify the ColdFire initialisation code to insert additional wait states to compensate for the slower
MC68340 operating frequency.
The schematic also shows the decoupling capacitors that need to be connected to all chips on the reference
design to minimize the effects of noise in the system. The capacitors are connected between the power and
ground planes of the module. 0.1uF and 1nF capacitors are used to inhibit both low and high frequency noise
in the system.
= (BR + BR_340) * /RESET
= BR_340 * BG_DMA * /BG * /RESET
= BR_340 * /BG * /RESET
= BR * BG_DMA * /BG_340 * (BG + /BR_340) * /RESET ; Bus grant to the 5206
= BR * /BG_340 * (BG + /BR_340) * /RESET ; Bus grant to the 5206
MC68340 Gateway Reference Design
Considerations for Implementing a MCF5206e Gateway Board
; OR together bus requests.
; Bus grant to the 340 H/W,
; Bus grant to the 340 H/W,
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