vsc055xkm-01 Maxim Integrated Products, Inc., vsc055xkm-01 Datasheet - Page 81

• Manufacturer Part Number: vsc055xkm-01
• Description: Enhanced I?c Backplane Controller
• Manufacturer: Maxim Integrated Products, Inc.

VSC055-01
Data Sheet
Table 5. LED Options (continued)
Table 6. Input Edge Combinations
3.2.74 88h: Pulse Train Control 80 (PTC80)
Table 6
This register, along with the PTC81 register, provides a user-programmable LED flashing pulse train that
defines the 0.33 Hz flash rate (selectable in the bit control registers) at power on. The user can adjust the
pulse duration, the pulse train length, and the on/off time to derive a specific visual indication. The PTC80
register provides eight of the twelve bits available in the programmable pulse train. The PTC81 register
contains two bits of pulse-width programmability, two bits of pulse train length programmability, and the
remaining four bits of the programmable pulse train.
As an example, the pulse train can be used to develop a visual heartbeat indication by programming the
PTC80 register with a 45h and the PTC81 register with a 01h. This combination develops a pulse train
with two blinks followed by a gap with the on times of the LED equal to 166.67 ms.
If the default values of this register or the PTC51 register are modified, and synchronization to other LED
flash rates is desired, the SYNC# pin must be enabled. To enable the SYNC# pin, tie the SYNCEN pin to
V
value in bits 3:0 of the Clock Select Control register. For information on the Clock Select Control register,
see
The following table shows the bit assignments for the Pulse Train Control 80 register.
Register Name:
Address:
Reset Value:
Bit
7:0
DD
PTE
“FDh: Clock Select Control (CSC),”
FS2
1
1
, connect an external 10 kΩ pull-up resistor to the SYNC# pin, and place the proper synchronization
X
X
X
0
1
shows the available input edge combinations.
Bit Label
PT7-0
FS2
1
1
FS1
0
0
1
1
0
PTC80
88h
0011_1111b
FS1
1
1
Access
R/W
FS0
0
1
0
1
0
FS0
0
1
Description
Pulse Train
These eight bits are the first bits shifted out from 0 to 7 and define the on/off
time for the 0.33 Hz (FS2-FS0 = 010b in the selected Bit Control register) flash
rate.
1: defines LED on time.
0: defines LED off time.
DD
1
1
1
1
1
page 111.
DD
81 of 133
0
0
GPD
GPD
X
X
X
X
X
1
1
I/O State
Pulse Train 6 selected, drive to V
Pulse Train 7 selected, drive to V
Interrupt Condition
No interrupt generated, default
Interrupt generated on a rising edge
Interrupt generated on a falling edge
Interrupt generated on either edge
No interrupt generated
DD
DD
only
only
January 2008
Revision 4.1