PC104P-SIO4BX User Manual, Revision: 0
General Standards Corporation
8302A Whitesburg Drive Huntsville, AL 35802, Phone: (256) 880-8787
2.1.3
Board Status: Local Offset 0x0008
The Board Status Register gives general overall status for a board. The Board Jumpers are physical jumpers which
can be used to distinguish between boards if multiple SIO4 boards are present in a system.
D31
Board Reset In Progress
D30:D16
RESERVED
D15
External Ch4 Rx FIFO Not Present
D14
External Ch4 Tx FIFO Not Present
D13
External Ch3 Rx FIFO Not Present
D12
External Ch3 Tx FIFO Not Present
D11
External Ch2 Rx FIFO Not Present
D10
External Ch2 Tx FIFO Not Present
D9
External Ch1 Rx FIFO Not Present
D8
External Ch1 Tx FIFO Not Present
D7:D2
RESERVED
D1
Board Jumper 1
0 = Jumper J5:3-4 installed
D0
Board Jumper 0
0 = Jumper J5:1-2 installed
2.1.5 Channel Tx Almost Flags: Local Offset 0x0010 / 0x0020 / 0x0030 / 0x0040
The Tx Almost Flag Registers are used to set the Almost Full and Almost Empty Flags for the transmit FIFOs. The
FIFO almost flags may be used to determine a fill level for a specific transfer size.
D31:16
Tx Almost Full Flag Value
Almost Full Flag will be asserted when the FIFO has space for “Almost Full Value”
words or fewer (i.e. FIFO contains (FIFO Size – Almost Full Value) words or more.)
D15:0
Tx Almost Empty Flag Value
Almost Empty Flag will be asserted when the FIFO contains “Almost Empty Value”
words or fewer.
2.1.6 Channel Rx Almost Flags: Local Offset 0x0014 / 0x0024 / 0x0034 / 0x0044
The Rx Almost Flag Registers are used to set the Almost Full and Almost Empty Flags for the receive FIFOs. The
FIFO almost flags may be used to determine a fill level for a specific transfer size.
D31:16
Rx Almost Full Flag Value
Almost Full Flag will be asserted when the FIFO has space for “Almost Full Value”
words or fewer (i.e. FIFO contains (FIFO Size – Almost Full Value) words or more.)
D15:0
Rx Almost Empty Flag Value
Almost Empty Flag will be asserted when the FIFO contains “Almost Empty Value”
words or fewer.
2.1.7 Channel FIFO: Local Offset 0x0018 / 0x0028 / 0x0038 / 0x0048
The Channel FIFO Register passes serial data to/from the serial controller chips. The same register is used to access
both the Transmit FIFO (writes) and Receive FIFO (reads).
D31:8
RESERVED
D7:0
Channel FIFO Data
