Motorola MSC8101 ADS User's Guide Page 66

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2-14 MSC8101 User’s Guide
Reset Configuration and Boot
2.4.1 Host Reset Configuration Sequence
This section describes how the reset configuration word is applied to a host-controlled
MSC8101. Host reset configuration allows the host to program the reset configuration
word via the host port after
PORESET is deasserted. If HPE is sampled high at the rising
edge of
PORESET, the host port is enabled. In this mode the RSTCONF pin must be pulled
up deasserted. The device extends the internal
PORESET until the host programs the reset
configuration word register. The host must write four 8-bit half-words to the host reset
configuration register address to program the reset configuration word, which is 32-bits
wide.
1
This register is programmed before the internal PLL and DLL in the MSC8101 are
locked. The host must program this register after the rising edge of
PORESET input. The
host has its own clock and does not depend on the MSC8101 clock. After the PLL and
DLL are locked,
HRESET remains asserted for another 512 bus clocks and is then released.
The
SRESET is released three bus clocks later.
2.4.1.1 Reset Configuration Word Value
In the system depicted in Figure 2-5, the host MSC8101 transfers data and control to/from
the other MSC8101s through the host port. The host uses its address and data buses for
data transfers. Only the host can initiate transactions, so there is no need for a system
arbiter. The host accesses external memory via its PowerPC system bus. The other
MSC8101s connect to their own external memory, a memory for each MSC8101, so there
is no need for a system memory controller.
1. For details on the host port registers, refer to the HDI16 chapter in the MSC8101 Reference Manual.
Table 2-10. Reset Configuration Word Values for Host Reset Configuration
Master MSC8101 Slave MSC8101 Devices
Value Description Value Description
EARB = 0 Internal arbitration EARB = 0 Internal arbitration
EXMC = 0 Internal memory controller EXMC = 0 Internal memory controller
EBM = 0 Single-chip mode EBM = 0 Single-chip mode
BPS = 01 8-bit boot port size according to the
example in Figure 2-5
BPS = 00 Boot occurs via the host port; this value
has no effect
SCDIS = 0 SC140 core enabled SCDIS = 0 SC140 core enabled
DLLDIS = 0 No DLL bypass for normal operation DLLDIS = 0 No DLL bypass for normal operation
ISB = 000 IMMR value is 0xF000_0000 ISB = 010 Each MSC8101 can have any IMMR value;
can be changed by boot
ISPS = 1 Select 32-bit PowerPC data bus ISPS = 1 Selects 32-bit PowerPC data bus
The rest of the fields should be configured according to system requirements: IRQ7INT, ISPS, IRPC, DPPC, NMI
OUT, BBD, TCPC, BC1PC. Assume they are all equal to zero.
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