Freescale Semiconductor MPC8313E PowerQUICC II Pro Family Reference Manual page 480

Enhanced Local Bus Controller
Table 10-22 describes LBCR fields.
Bits Name
0 LDIS Local bus disable
0 Local bus is enabled.
1 Local bus is disabled. No internal transactions will be acknowledged.
1–7 — Reserved
8–9 BCTLC Defines the use of LBCTL
00 LBCTL is used as W/R control for GPCM or UPM accesses (buffer control).
01 LBCTL is used as LOE for GPCM accesses only.
10 LBCTL is used as LWE for GPCM accesses only.
11 Reserved.
10 AHD Address hold disable. Removes part of the hold time for LAD with respect to LALE in order to lengthen
the LALE pulse.
0 During address phases on the local bus, the LALE signal negates 2 platform clock period prior to
the address being invalidated. At 66.6 MHz, this provides 3 ns of address hold time at the external
address latch.
1 During address phases on the local bus, the LALE signal negates 1 platform clock period prior to
the address being invalidated. This halves the address hold time, but extends the latch enable
duration. This may be necessary for very high frequency designs.
11–15 — Reserved. Reads to bit 13 return 1.
16–23 BMT Bus monitor timing. Defines the bus monitor time-out period. Clearing BMT (reset value) selects the
maximum count of bus clock cycles. For non-zero values of BMT, the number of LCLK clock cycles to
count down before a time-out error is generated is given by:
bus cycles = BMT × PS, where PS is set according to LBCR[BMTPS].
The value of BMT × PS must not be less than 40 bus cycles for reliable operation.
24–27 — Reserved
28–31 BMTPS Bus monitor timer prescale. Defines the multiplier, PS, to scale LBCR[BMT] for determining bus
time-outs.
0000 PS = 8
0001 PS = 16
0010 PS = 32
0011 PS = 64
0100 PS = 128
0101 PS = 256
0110 PS = 512
0111 PS = 1024
1000 PS = 2048
1001 PS = 4096
1010 PS = 8192
1011 PS = 16,384
1100 PS = 32,768
1101 PS = 65,536
1110 PS = 131,072
1111 PS = 262,144
MPC8313E PowerQUICC™ II Pro Integrated Processor Family Reference Manual, Rev. 2
10-32
Table 10-22. LBCR Field Descriptions
Description
Freescale Semiconductor