Boot Rom Program Execution And Operation Mode And Rom Configuration Block - Fujitsu MB96300 series Hardware Manual

CHAPTER 8 RESETS AND STARTUP
8.4 Boot ROM program execution and Operation mode and
ROM Configuration Block
When the reset signal is released, the MCU starts with the execution of the internal Boot
ROM program. The Boot ROM program reads the status of the mode pins (MD2-MD0),
which define the operation mode of the MCU. Depending on the mode pin setting, the
MCU activates the Parallel Flash Programming mode, the Serial Communication mode or
starts executing the User program.
After the activation of the MCU operation mode, further Boot ROM program execution is
defined by the configuration stored in the so-called ROM Configuration Block in Flash/
ROM, which also determines the Boot Vector (user program start address).
Finally, the Boot ROM program will start execution of the user program at the Boot
Vector.
■ External bus
By default, the Boot Vector (user program start address) is read from the fixed address FF:FFDC
Devices with external bus interface allow reading the Boot Vector from external memory. Depending on the
mode pin setting, three different external bus configurations can be selected for reading the Boot Vector.
The Boot ROM program reads the Boot Vector and the mode byte from a fixed address. The bus
configuration is changed according to the given mode byte and the user program is started at the given
address (Boot Vector).
■ Mode pins
The mode pins MD[2:0] define the operation mode of the MCU. The mode pin setting is internally sampled
and can only be changed by a Power or External reset event (the Mode pin data is sampled when the signals
PRST and ERST defined in Figure 8.3-1 "Block diagram of reset extension circuit" are both deactivated).
Hence the operation mode cannot be changed by a Clock stop detection, Software or Watchdog timer reset
event.
The sampled mode pin signals are read by the Boot ROM program after reset release, which determines the
operation mode according to the following table.
Table 8.4-1 Mode Pin settings
Mode pin setting
Operation mode
MD2 MD1 MD0
External Vector
0 0 0
mode 0
External Vector
0 0 1
mode 1
200
Boot Vector
name Source
External
memory
External
memory
MB96300 Super Series Hardware Manual
Configuration of
external bus for
Boot Vector read
access
Available only for
8 bits, address/data
devices with external
multiplexed
bus interface
Available only for
16 bits, address/data
devices with external
multiplexed
bus interface
.
H
Remarks