4.4J11 - 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.
DMA Channel | Pins |
| |
Channel 1 | 1&7 |
| 2&8 |
Channel 2 | 3&9 |
| 4&10 |
Channel 3 | 5&11 |
| 6&12 |
| |
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.
4.5J7 - 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 |
