Datasheet

DS21352/DS21552
62 of 137
11.2.1 FIXED PER-CHANNEL IDLE CODE INSERTION
The first method on the receive side involves using the Receive Mark Registers (RMR1/2/3) to determine
which of the 24 T1 channels should be overwritten with either a 7Fh idle code or with a digital milliwatt
pattern. The RCR2.7 bit will determine which code is used. The digital milliwatt code is an eight byte
repeating pattern that represents a 1 kHz sine wave (1E/0B/0B/1E/9E/8B/8B/9E). Each bit in the RMRs,
represents a particular channel. If a bit is set to a one, then the receive data in that channel will be
replaced with one of the two codes. If a bit is set to zero, no replacement occurs.
RMR1/RMR2/RMR3: RECEIVE MARK REGISTERS (Address=2D to 2F Hex)
(MSB) (LSB)
CH8 CH7 CH6 CH5 CH4 CH3 CH2 CH1 RMR1(2D)
CH16 CH15 CH14 CH13 CH12 CH11 CH10 CH9 RMR2(2E)
CH24 CH23 CH22 CH21 CH20 CH19 CH18 CH17 RMR3(2F)
SYMBOLS POSITIONS NAME AND DESCRIPTION
CH1-24 RMR1.0-3.7
Receive Channel Mark Control Bits
0 =do not affect the receive data associated with this channel
1 = replace the receive data associated with this channel with idle code or digital
milliwatt code (depends on the RCR2.7 bit)
11.2.2 UNIQUE PER-CHANNEL CODE INSERTION
The second method involves using the Receive Channel Control Registers (RCC1/2/3) to determine
which of the 24 T1 channels off of the T1 line and going to the backplane should be overwritten with the
code placed in the Receive Channel Registers (RC1 to RC24). This method is more flexible than the first
in that it allows a different 8–bit code to be placed into each of the 24 T1 channels.
RC1 TO RC24: RECEIVE CHANNEL REGISTERS (Address=80 to 8F and 58 to
5F Hex)
(for brevity, only channel one is shown; see Table 5-1 for other register address)
(MSB) (LSB)
C7 C6 C5 C4 C3 C2 C1 C0 RC1 (80)
SYMBOL POSITION NAME AND DESCRIPTION
C7 RC1.7 MSB of the Code (this bit is sent first to the backplane)
C0 RC1.0 LSB of the Code (this bit is sent last to the backplane)