Datasheet

DS21Q50
42 of 87
7. DS0 MONITORING FUNCTION
Each DS21Q50 framer 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 determines which
channel is to be monitored by properly setting the TCM0 to TCM4 bits in the CCR3 register. In the
receive direction, the RCM0–RCM4 bits in the CCR4 register need to be properly set. The DS0 channel
pointed to by the TCM0–TCM4 bits appear in the transmit DS0 monitor (TDS0M) register; the DS0
channel pointed to by the RCM0–RCM4 bits appear in the receive DS0 (RDS0M) register. The TCM4–
TCM0 and RCM4–RCM0 bits should be programmed with the decimal decode of the appropriate E1
channel. For example, if DS0 channel 6 in the transmit direction and DS0 channel 15 in the receive
direction need to be monitored, the following values are programmed into CCR4 and CCR5:
TCM4 = 0 RCM4 = 0
TCM3 = 0 RCM3 = 1
TCM2 = 1 RCM2 = 1
TCM1 = 0 RCM1 = 1
TCM0 = 1 RCM0 = 0
Register Name: CCR3 (Repeated here from Section 3 for convenience.)
Register Description:
Common Control Register 3
Register Address:
14 Hex
Bit 7 6 5 4 3 2 1 0
Name RLB LLB LIAIS TCM4 TCM3 TCM2 TCM1 TCM0
NAME BIT FUNCTION
RLB 7 Remote Loopback
LLB 6 Local Loopback
LIAIS 5 Line Interface AIS Generation Enable
TCM4 4
Transmit Channel Monitor Bit 4. MSB of a channel decode that determines which transmit
channel data appears in the TDS0M register. See Section 6
or details.
TCM3 3 Transmit Channel Monitor Bit 3
TCM2 2 Transmit Channel Monitor Bit 2
TCM1 1 Transmit Channel Monitor Bit 1
TCM0 0 Transmit Channel Monitor Bit 0. LSB of the channel decode.