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4.4 J11 - Receive DMA Channel Selection
J11 selects the DMA channel to be used for receive DMA. Three channels (1 - 3)
are available on the MPA-200 for DMA. When selecting a DMA channel, both
the DMA acknowledge (DACK) and the DMA request (DRQ) for the appropriate
channel need to be selected. Table 9 summarizes the jumper block selections for
J11.
Table 9 Jumper block J11 selections.
6&12
5&11Channel 3
4&10
3&9Channel 2
2&8
1&7Channel 1
PinsDMA Channel
NOTE:
Since it is illegal to perform transmit DMA and receive DMA on the
same DMA channel, jumper blocks J10 and J11 should never have the
same pins connected. This condition could result in damage to the
system.
4.5 J7 - Line Driver Control Selection
J7 controls the source for enabling and disabling the driver circuitry on the
MPA-200. By selecting pins 1 & 2, the transmitters on the MPA-200 will always
be enabled. If the user wants the ability to enable and disable the transmitters, pins
2 & 3 should be selected. By doing this, the transmitters are controlled by bit D0
of the communications register. Similarly, by selecting pins 4 & 5, the receivers
on the MPA-200 will always be enabled. If pins 5 & 6 are selected, the receivers
are controlled by bit D1 of the communications register. Table 10 summarizes the
jumper block selections for J7.
13 Quatech Inc., MPA-200/300 Manual