Motorola MSC8101 ADS User's Guide Page 217

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Select the TSA Channel Route to a TDM Timeslot
Multi-Channel Controllers (MCCs) 10-15
Figure 10-9. Serial Interface Entry Definitions for Driver Example
10.4.2 Set up Clocks, Baud Rate Generators (BRG), and Timers
The TDMB clocks (L1RCLKB, L1TCLKB) are always driven from an external source. In
our example, they are configured to be driven from the CLK[15–16] pins (the CMX SI2
Clock Route Register [CMXSI2CR] is cleared to 0x0). The reference clock input to these
pins is either from the T1/E1 framer, in external PHY loopback, or from the BRG in
internal (SI or TDM) loopback. The driver implements internal loopback clock generation
via BRG5. The BRG5 output is a fraction of the CPM BRGCLK clock and is determined
by the division factors programmed in the BRG Configuration (BRGC) registers. To give
a clock rate of ~2.048 MHz from a 150 MHz CPM, BRGC5 is set to 0x00010048. The
BRG is set for normal operation, with no prescaler and a clock divider of 37. The clocks
produced by the BRGs are sent to the bank-of-clocks logic, where they are either routed to
the serial controllers or to the external pins, as in this case. The
BRG50 pin must be
externally connected to the
CLK15 pin.
To provide the synchronization signals, the following CPM timer registers require
configuration:
1. Timer Global Configuration Register (TGCR). TGCR must be configured prior to
the TMR or erratic behavior can occur. Setting TGCR1 = 0x09 enables Timer1
with normal gate mode.
2. Timer Mode Register (TMR). Next, the TMR1 register is configured with the timer
prescaler set to 1, the capture event disabled and the timer counter is reset
immediately after the reference value is reached. The input source for the timer is
TIN1 (fed by BRG5); therefore TIMR1 is set to 0x000E.
Loop/
echo
Super
MCSEL
LST
CNT
BYT
Channel 160
Rx entry
Channel 160
Tx entry
Channel 191
Rx entry
Channel 191
Tx entry
0
1 0 1 0 0 0 0 0
0 0 01
1
1
1
1
1
1
0
0
0
0
0
0
0
1
0 0 0
0 0 0
0 0 0
1 0 1 0 0 0 0 0
1 0 1 1 1 1 1 1
1 0 1 1 1 1 1 1
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