HS1-82C54RH-Q Intersil, HS1-82C54RH-Q Datasheet - Page 10

• Manufacturer Part Number: HS1-82C54RH-Q
• Manufacturer: Intersil
• Type: Programmabler

Specifications of HS1-82C54RH-Q

• # Internal Timers: 1
• Operating Supply Voltage (typ): 5V
• Package Type: SBDIP
• Pin Count: 24
• Operating Temp Range: -55C to 125C
• Operating Temperature Classification: Military
• Mounting: Through Hole
• Lead Free Status / RoHS Status: Compliant

Commands, one for each Counter latched. Each Counter’s
latched count is held until it is read (or the Counter is
reprogrammed). That Counter is automatically unlatched
when read, but other Counters remain latched until they are
read. If multiple count Read-Back Commands are issued to
the same Counter without reading the count, all but the first
are ignored; i.e., the count which will be read is the count at
the time the first Read-Back Command was issued.
The Read-Back Command may also be used to latch status
information of selected Counter(s) by setting STATUS bit
D4 = 0. Status must be latched to be read; status of a
Counter is accessed by a read from that Counter.
The Counter status format is shown in Figure 13. Bits D5
through D0 contain the Counter’s programmed Mode exactly
as written in the last Mode Control Word. OUTPUT bit D7
contains the current state of the OUT pin. This allows the
user to monitor the Counter’s output via software, possibly
eliminating some hardware from a system.
NULL COUNT bit D6 indicates when the last count written to
the Counter Register (CR) has been loaded into the
Counting Element (CE). The exact time this happens
depends on the Mode of the Counter and is described in the
Mode Definitions, but until the count is loaded into the
Counting Element (CE), it can’t be read from the Counter. If
the count is latched or read before this time, the count value
D7 1 = Out Pin is 1
D6 1 = Null count
D5-D0 = Counter programmed mode (See Figure 5)
OUT
PUT
D7
D7
1
1
1
1
1
1
0 = Out pin is 0
0 = Count available for reading
D6
1
1
1
1
1
1
COUNT
NULL
D6
D5
0
1
1
0
0
1
FIGURE 13. STATUS BYTE
COMMAND
RW1
D4
D5
0
0
0
1
0
0
D3
RW0
0
0
1
1
0
0
10
D4
D2
0
1
1
0
1
1
M2
D3
D1
1
0
0
0
0
0
FIGURE 15. READ-BACK COMMAND EXAMPLE
D2
M1
D0
0
0
0
0
0
0
M0
D1
Read back count and status of
Counter 0
Read-back status of Counter 1
Read-back status of Counters 2, 1
Read-back count of Counter 2
Read-back count and status of Counter 1
Read-back status of Counter 1
BCD
D0
HS-82C54RH
DESCRIPTION
will not reflect the new count just written. The operation of
Null Count is shown in Figure 14.
NOTES:
17. Only the Counter specified by the Control Word will have its Null
18. If the Counter is programmed for two-byte counts (least
If multiple status latch operations of the Counter(s) are
performed without reading the status, all but the first are
ignored; i.e., the status that will be read is the status of the
Counter at the time the first status Read-Back Command
was issued.
Both count and status of the selected Counter(s) may be
latched simultaneously by setting both COUNT and STATUS
bits D5, D4 = 0. This is functionally the same as issuing two
separate Read-Back Commands at once, and the above
discussions apply here also. Specifically, if multiple count
and/or status Read-Back Commands are issued to the same
Counter(s) without any intervening reads, all but the first are
ignored. This is illustrated in Figure 15.
If both count and status of a Counter are latched, the first
read operation of that Counter will return latched status,
regardless of which was latched first. The next one or two
reads (depending on whether the Counter is programmed for
one or two byte counts) return latched count. Subsequent
reads return unlatched count.
A. Write to the Control Word Register: (Note 17) Null Count = 1
B. Write to the Count Register (CR): (Note 18)
C. New count is loaded into CE (CR
Count set to 1. Null Count bits of other Counters are unaffected.
significant byte then most significant byte) Null Count goes to 1
when the second byte is written.
FIGURE 14. NULL COUNT OPERATION
THIS ACTION:
Count and status latched for Counter 0
Status latched for Counter 1
Status latched for Counter 2, but not
Counter 1
Count latched for Counter 2
Count latched for Counter 1, but not status
Command ignored, status already latched
for Counter 1
CE):
RESULT
Null Count = 1
Null Count = 0
CAUSES: