Rainbow Electronics DS21458 - Manual (Page 91)

DS21455/DS21458 Quad T1/E1/J1 Transceivers
91 of 270
16. DS0 MONITORING FUNCTION
The DS21455/DS21458 can monitor one DS0 64kbps channel in the transmit direction and one DS0
channel in the receive direction at the same time. In the transmit direction the user will determine which
channel is to be monitored by properly setting the TCM0 to TCM4 bits in the TDS0SEL register. In the
receive direction, the RCM0 to RCM4 bits in the RDS0SEL register need to be properly set. The DS0
channel pointed to by the TCM0 to TCM4 bits will appear in the transmit DS0 monitor (TDS0M) register
and the DS0 channel pointed to by the RCM0 to RCM4 bits will appear in the receive DS0 (RDS0M)
register. The TCM4 to TCM0 and RCM4 to RCM0 bits should be programmed with the decimal decode
of the appropriate T1 or E1 channel. T1 channels 1 through 24 map to register values 0 through 23. E1
channels 1 through 32 map to register values 0 through 31. For example, if DS0 channel 6 in the transmit
direction and DS0 channel 15 in the receive direction needed to be monitored, then the following values
would be programmed into TDS0SEL and RDS0SEL:
TCM4 = 0 RCM4 = 0
TCM3 = 0 RCM3 = 1
TCM2 = 1 RCM2 = 1
TCM1 = 0 RCM1 = 1
TCM0 = 1 RCM0 = 0
16.1 Transmit DS0 Monitor Registers
Register Name:
TDS0SEL
Register Description: Transmit Channel Monitor Select
Register Address: 74h
Bit
# 7 6 5 4 3 2 1 0
Name — — — TCM4 TCM3 TCM2 TCM1 TCM0
Default 0 0 0 0 0 0 0 0
Bits 0 to 4 Transmit Channel Monitor Bits (TCM0 to TCM4). TCM0 is the LSB of a 5-bit channel select that determines
which transmit channel data will appear in the TDS0M register.
Bits 5 to 7/Unused, must be set to zero for proper operation.
Register Name:
TDS0M
Register Description: Transmit DS0 Monitor Register
Register Address: 75h
Bit
# 7 6 5 4 3 2 1 0
Name B1 B2 B3 B4 B5 B6 B7 B8
Default
0 0 0 0 0 0 0 0
Bits 0 to 7/Transmit DS0 Channel Bits (B1 to B8). Transmit channel data that has been selected by the transmit channel
monitor select register. B8 is the LSB of the DS0 channel (last bit to be transmitted).