
92
Agere Systems Inc.
Data Sheet
May 2001
and Packet Payload Engine
Ambassador T8110 PCI-Based H.100/H.110 Switch
8 Frame Group and FG I/O
(continued)
8.2 FG7 Timer Option
The FG7 signal allows for an added function of a timer output, via a 16-bit programmable counter.
8.2.1 FG7 Counter (Low and High Byte) Registers
The FG7 counter (low and high byte) registers set the timer value. The timer is actually a divider, so the value
entered must be [divider value – 1], i.e., 0000000000000011 would yield a div-by-4 operation. The FG7 mode lower
register enables the timer option, with two clock source options: T8110 internal frame or an external timer clock via
the FG6 signal. The FG7 mode upper register controls the shape of the timer pulse. For more details, see Section
8.4.3 on page 97.
*
Normal operation allows frame group or FGIO control via registers 0x00470—473. Enabling the counter overrides 0x00470—473 settings.
Square wave is only available when FG7 counter high/low value is a binary multiple 1, 2, 4, 8, 16, etc. Other values yield a carry out pulse
shape.
Carry out pulse is active for one FG7 timer clock period.
§Programmable pulses are based on T8110 internal 32.768 MHz clock periods.
Table 71. FG7 Counter (Low and High Byte) Registers
Byte
Address
0x00474 FG7 Counter, Low Byte
0x00475 FG7 Counter, High Byte
0x00476 FG7 Mode Lower
Name
Bit
Mnemonic
Value
Function
7:0
7:0
7:0
FCLLR
FCULR
F7MSR
LLLL LLLL Lower 8 bits of 16-bit counter value.
LLLL LLLL Upper 8 bits of 16-bit counter value.
0000 0000
0000 0001
0000 0010
Enable timer, clock = external FG6.
0
Normal FG7 timer output, high pulses
(default).
Inverted FG7 timer output, low pulses.
000
001
010
100
FG7 timer output = programmable pulse
§
.
0001
0010
0100
1000
Programmable pulse width = 122 ns.
Normal operation* (default).
Enable timer, clock = internal frame.
0x00477 FG7 Mode Upper
7
FCISB
1
6:4
F7SSP
FG7 timer output off (default).
FG7 timer output = square wave
.
FG7 timer output = carry out pulse
.
3:0
F7WSN
Programmable pulse width = 30.5 ns.
Programmable pulse width = 61.0 ns.
Programmable pulse width = 91.5 ns.