CR27
used to select the IRQ for serial port 1 (bits 7:4) and for
serial port 2 (bits 3:0). Refer to IRQ Table for CR27. Any
This register can only be accessed in the Configuration
Mode and after the CSR has been initialized to 27H.
The default value of this register after power up is 00H.
This register is used to select the IRQ for the FDC (Bits
4:7) and the parallel port (bits 3:0). Any unselected IRQ
output (registers CR27-CR29) is in tristate.
unselected IRQ output (registers CR27
tristate.
- CR29) is in
To properly share an IRQ among UART1 and UART2:
1)
2)
Configure UART1 to use the desired IRQ pin.
Set UART2 to 0Fh i.e., set CR28 bits[3:0]=1111.
This selects the share IRQ mechanism. Refer
to Table 60 on the following page:
CR28
This register can only be accessed in the Configuration
Mode and after the CSR has been initialized to 28H. The
default value of this register after power up is 00H. This
register
is
D3-D0 or
D7-D4
IRQ Selected
None
0000
0001
0010
0011
0100
0101
0110
0111
1000
IRQ_A
IRQ_B
IRQ_C
IRQ_D
IRQ_E
IRQ_F
Reserved
IRQ_H
CR29
used to select the IRQ for IRQIN (bits 3:0). Refer to IRQ
Table for CR27. Bits 7:4 are reserved and return zero
This register can only be accessed in the Configuration
Mode and after the CSR has been initialized to 29H. The
default value of this register after power up is 00H. This
when read.
Any unselected IRQ output (registers
CR27-CR29) is in tristate.
register
is
134
SMSC [ SMSC CORPORATION ]
