Quatech MPAP-100 - Manual (Page 39)

10.3.2 Using channel B for receive
The MPAP-100 supplies only limited support for SCC channel B. This mode, therefore,
is not recommended for most applications. Set RXSRC (bit 1) in the Configuration Register to
logic 1. This will configure the MPAP-100 to use W/REQA for transmit DMA and W/REQB for
receive DMA. In addition to any other desired SCC configuration, ensure that the following bits
are set according to Table 7:
Enable receive interrupts on special conditions
only (recommended), or disable them completely. 11 or
00
4-3
Use W/REQB for receive. 1 5
Set W/REQB for DMA Request mode. 1 6
Enable DMA request on W/REQB. This bit
should be set after the other bits in WR1 are set as
desired.
1 7
WR1B
Assert transmit DMA request when entry location
of internal FIFO is empty.
0 5 WR7A'
Enable WR7A'. 1 0 WR15A
Disable DMA request-on-transmit on
DTR/REQA.
0 2 WR14A
Disable transmit interrupts. 0 1
Use W/REQA for transmit. 0 5
Set W/REQA for DMA Request mode. 1 6
Enable DMA request on W/REQA. This bit
should be set after the other bits in WR1 are set as
desired.
1 7
WR1A
Function Value Bit(s) Register
Table 7 --- Configuring the SCC for Rx DMA on channel B