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6 series termination required for ultra dma – FUJITSU MHR2030AT User Manual

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Interface

5-126

C141-E145-02EN

i)

The CRC generator polynomial is : G (X) = X16 + X12 + X5 + 1.

Note: Since no bit clock is available, the recommended approach for

calculating CRC is to use a word clock derived from the bus strobe.
The combinational logic shall then be equivalent to shifting sixteen
bits serially through the generator polynomial where DD0 is shifted in
first and DD15 is shifted in last.

5.5.6 Series termination required for Ultra DMA

Series termination resistors are required at both the host and the device for
operation in any of the Ultra DMA Modes. The following table describes
recommended values for series termination at the host and the device.

Table 5.17 Recommended series termination for Ultra DMA

Signal

Host Termination

Device Termination

DIOR-:HDMARDY-:HSTROBE

22 ohm

82 ohm

DIOW-:STOP

22 ohm

82 ohm

CS0-, CS1-

33 ohm

82 ohm

DA0, DA1, DA2

33 ohm

82 ohm

DMACK-

22 ohm

82 ohm

DD15 through DD0

33 ohm

47 ohm

DMARQ

82 ohm

22 ohm

INTRQ

82 ohm

22 ohm

IORDY:DDMARDY-:DSTROBE

82 ohm

33 ohm

RESET-

33 ohm

Note: Only those signals requiring termination are listed in this table. If a signal is not listed,

series termination is not required for operation in an Ultra DMA Mode. For signals also
requiring a pull-up or pull-down resistor at the host see Figure 5.8.

Figure 5.8 Ultra DMA termination with pull-up or pull-down

Vcc

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