FW82801EB Intel, FW82801EB Datasheet - Page 352

• Manufacturer Part Number: FW82801EB
• Manufacturer: Intel

Specifications of FW82801EB

• Lead Free Status / RoHS Status: Not Compliant

LPC Interface Bridge Registers (D31:F0)
9.3.1
352
TCW—Timer Control Word Register
(LPC I/F—D31:F0)
I/O Address:
Default Value:
This register is programmed prior to any counter being accessed to specify counter modes.
Following part reset, the control words for each register are undefined and each counter output is 0.
Each timer must be programmed to bring it into a known state.
There are two special commands that can be issued to the counters through this register, the Read
Back Command and the Counter Latch Command. When these commands are chosen, several bits
within this register are redefined. These register formats are described below.
Bit
7:6
5:4
3:1
0
Counter Select — WO. The Counter Selection bits select the counter the control word acts upon as
shown below. The Read Back Command is selected when bits[7:6] are both 1.
00 = Counter 0 select
01 = Counter 1 select
10 = Counter 2 select
11 = Read Back Command
Read/Write Select — WO. These bits are the read/write control bits. The actual counter
programming is done through the counter port (40h for counter 0, 41h for counter 1, and 42h for
counter 2).
00 = Counter Latch Command
01 = Read/Write Least Significant Byte (LSB)
10 = Read/Write Most Significant Byte (MSB)
11 = Read/Write LSB then MSB
Counter Mode Selection — WO. These bits select one of six possible modes of operation for the
selected counter.
000 = Mode 0
001 = Mode 1
x10 = Mode 2
x11 = Mode 3
100 = Mode 4
101 = Mode 5
Binary/BCD Countdown Select — WO.
0 = Binary countdown is used. The largest possible binary count is 2 16
1 = Binary coded decimal (BCD) count is used. The largest possible BCD count is 10 4
43h
All bits undefined
Out signal on end of count (=0)
Hardware retriggerable one-shot
Rate generator (divide by n counter)
Square wave output
Software triggered strobe
Hardware triggered strobe
Intel
Description
Attribute:
Size:
®
82801EB ICH5 / 82801ER ICH5R Datasheet
WO
8 bits