Overhead Interface - NEC UPD98413 User Manual

2.2.4 Overhead Interface

The overhead interface is used to transfer the contents of the transport overhead (TOH) and path overhead (POH)
that are exchanged between the peripheral device and
Pin Name Serial No.
TOHCK0-3
TTOHFP0-3
TPOHFP0-3
TOHD[1:0]0-3
TOHAV0-3
CHAPTER 2 PIN FUNCTION
µ
PD98413.
Address No. I/O Level
O
LVTTL
O
LVTTL
O
LVTTL
I
LVTTL
I
LVTTL
PRELIMINARY
Function
Transmit overhead interface clock output (19.44 MHz).
This pin outputs a 19.44MHz obtained by internally dividing
transmit clock TCLK (622.08 MHz) by 32. TTOHFP,
TPOHFP and TOHD are output in sync with this divided
clock.
Transmit TOH frame pulse output.
This signal is driven high 2 clock cycle before the inputs of
transmit TOH data is started.
Transmit POH frame pulse output.
This signal is driven high 2 clock cycle before the inputs of
transmit POH data is started.
Transmit TOH /POH data input 2-bit bus.
This is a 2-bit data bus that inputs transmit TOH /POH data.
It inputs the TOH / POH data on TOHD as 1 byte in 4 clock
cycles, starting to data input from 2 clock cycle later
TTOHFP is output.
Transmit TOH / POH data validity indication signal input.
µ
This signal informs the PD98413 that valid TOH / POH
data has been output to TOHD. The
TOHAV at the rising edge of TOHCK at the first clock of the
four clock cycles in which TOH / POH data is input. If
µ
TOHAV is high, the PD98413 inputs the data on TOHD in
that cycle and the next three cycles; when TOHAV is low,
µ
the PD98413 does not input the data.
NEC confidential and Proprietary
(1/2)
µ
PD98413 samples
27