MCF5272 查看數據表（PDF） - Oxford Semiconductor

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MCF5272

Interfacing OTG243 USB Host/Function/OTG Controller to MCF5272 ColdFire Processor

Oxford Semiconductor 

TransDimension Inc.

Interfacing OTG243 to Motorola MCF5272 ColdFire Processor

Crystal Oscillator and PLL: OSC1 and OSC2

In the reference design, a 6 MHz parallel resonance quartz crystal is connected across OSC1 and

OSC2. The following circuit is recommended.

6.000 MHz

100

6.8 pF

6.8 pF

OTG243

OSC1

OSC2

Figure 3: OTG243 crystal oscillator circuit

To meet the USB frequency accuracy and stability requirements, the crystal should have an

accuracy and stability better than 200 ppm. For a 6 MHz resonance quartz crystal, the

recommended ESR value should be less than 100 Ω.

DMA: DRQ1, DACK1, EOT1, DRQ2, DACK2, and EOT2

In this reference design, DMA is not tested and not supported.

When these signals are not used, proper connections should be made by pulling up or down

according to the application.

The logic levels of DRQ1 and DRQ2 at the time of hardware reset determine the frequency of the

oscillation imposed on the OSC1 and/or OSC2 pins. In this reference design, a 6 MHz crystal is

employed. Therefore the DRQ1 and DRQ2 should be tied with pull-down resistors smaller than

10kΩ.

Since DACK1, DACK2, EOT1, and EOT2 signals are all configured as inputs and active low

signals right after reset, they should be pulled-up by resistors.

Note: Even though the MCF5272 has a one-channel DMA controller internal to MCF5272,

which supports memory-to-memory DMA transfers that can be used for block data moves, it

does not require any external signals for DMA transfer. It uses normal memory access signals for

DMA transfer.

Remote Wakeup: WAKEUP

This pin is only meaningful if Port 1 of the OTG243 is assuming the role of a USB function. In

this reference design, a MCF5272 GPIO pin (PC13) is assigned to it. Since WAKEUP is active

high, a pull-down resistor is recommended.

External Pull-Up: RPU

If the internal pull-up resistor does not satisfy the USB 1.5KΩ pull-up tolerance, an external

1.5KΩ +/- 1% can be connected from RPU signal to DP1 signal.

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