Maxim Integrated DS33R11 - Manual (Page 81)

DS33R11 Ethernet Mapper with Integrated T1/E1/J1 Transceiver
81 of 344
10.8 DS0 Monitoring Function
The transceiver has the ability to 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 TR.TDS0SEL register. In the receive direction, the
RCM0 to RCM4 bits in the TR.RDS0SEL register need to be properly set. The DS0 channel pointed to by the
TCM0 to TCM4 bits appear in the transmit DS0 monitor (TR.TDS0M) register. The DS0 channel pointed to by the
RCM0 to RCM4 bits appear in the receive DS0 (TR.RDS0M) register. The TCM4 to TCM0 and RCM4 to RCM0
bits should be programmed with the decimal decode of the appropriate T1or 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 TR.TDS0SEL and TR.RDS0SEL:
TCM4 = 0 RCM4 = 0
TCM3 = 0 RCM3 = 1
TCM2 = 1 RCM2 = 1
TCM1 = 0 RCM1 = 1
TCM0 = 1 RCM0 = 0