82801FB Datasheet, PDF (371/786 Pages) Intel Corporation – Intel I/O Controller Hub 6 (ICH6) Family

LPC Interface Bridge Registers (D31:F0)
10.3.2
SBYTE_FMT—Interval Timer Status Byte Format Register
(LPC I/F—D31:F0)
I/O Address:
Default Value:
Counter 0 = 40h,
Counter 1 = 41h,
Counter 2 = 42h
Bits[6:0] undefined, Bit 7=0
Attribute:
Size:
RO
8 bits per counter
Each counter's status byte can be read following a Read Back Command. If latch status is chosen
(bit 4=0, Read Back Command) as a read back option for a given counter, the next read from the
counter's Counter Access Ports Register (40h for counter 0, 41h for counter 1, and 42h for counter
2) returns the status byte. The status byte returns the following:
Bit
Description
Counter OUT Pin State — RO.
7 _{0 = OUT pin of the counter is also a 0}
1 = OUT pin of the counter is also a 1
Count Register Status — RO. This bit indicates when the last count written to the Count Register
(CR) has been loaded into the counting element (CE). The exact time this happens depends on the
counter mode, but until the count is loaded into the counting element (CE), the count value will be
6
incorrect.
0 = Count has been transferred from CR to CE and is available for reading.
1 = Null Count. Count has not been transferred from CR to CE and is not yet available for reading.
Read/Write Selection Status — RO. These bits reflect the read/write selection made through
bits[5:4] of the control register. The binary codes returned during the status read match the codes
used to program the counter read/write selection.
5:4 ^{00 = Counter Latch Command}
01 = Read/Write Least Significant Byte (LSB)
10 = Read/Write Most Significant Byte (MSB)
11 = Read/Write LSB then MSB
Mode Selection Status — RO. These bits return the counter mode programming. The binary code
returned matches the code used to program the counter mode, as listed under the bit function
above.
000 = Mode 0 — Out signal on end of count (=0)
3:1 ^{001 = Mode 1 — Hardware retriggerable one-shot}
x10 = Mode 2 — Rate generator (divide by n counter)
x11 = Mode 3 — Square wave output
100 = Mode 4 — Software triggered strobe
101 = Mode 5 — Hardware triggered strobe
Countdown Type Status — RO. This bit reflects the current countdown type.
0 _{0 = Binary countdown}
1 = Binary Coded Decimal (BCD) countdown.
Intel^® I/O Controller Hub 6 (ICH6) Family Datasheet
371