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MB91360G Series
66
2.
BOOT ROM
The Boot ROM is a fixed start-up routine which is located at FF000 (Reset entry) and will therefore be executed
after every RST or INIT. The purpose of this ROM is to configure the device after a reset and to provide a simple
serial bootloader for programming the embedded Flash memories.
The Boot ROM contains three logical parts :
(1) Chip Initializations
Immediately after each reset, the following settings will be made :
CS0 : 200000…2FFFFF, 32 Bit Bus, 1 wait-state (default external access)
CS1 : 180000…1FFFFF, 32 Bit Bus, 1 wait-state (Flash Area only on F361GA)
CS7 : 100000…10FFFF, 16 Bit Bus, 1 wait-state (CAN)
In addition, the Table-Base Register will be initialized to 1FFC00 (F361GA only) and the synchronous reset (see
TBCR) will be enabled.
(2) Check for Bootcondition
After the chip initialization, the “Security-Vector” will be checked (Vector #66) . The purpose of this feature is to
disable the bootstraploader due to security reasons.
The RSRR (reset cause register) will be read and saved. If no power-on reset (external INIT input, RSRR
=
0x80) is indicated, a branch to the user application will be initiated (Branch to 1F4000) .
If INIT was detected and the “Security-Vector” check okay, the following conditions must be met in order to start
the Bootstraploader :
Within a certain time, the start-up character “V” must be received via UART0 (9600, 8N1) . The time-out is set
to 200 ms.
(3) Bootstraploader
If the Bootcondition was met, an acknowledge character “F” will be transmitted via UART0 to indicate that the
Bootloader is ready to accept commands. 4 different commands are possible :
Receive and write to a specified memory block
Dump the contents of a specified memory block
Initiate a “CALL” to a certain location
Re-dump a calculated checksum for verification
(4) Configuration Register (Mode Register F362MD)
This register is used to control which pins of the external bus interface are active, where the pins for the external
DMA channel are located and which I
2
C module is used.
address
000001FE
H
access
Initial value
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
bit 15
bit 14
bit 13
bit 12
bit 11
bit 10
bit 9
bit 8
ASYMCLKT
HIZ_D_A
HIZ_ECLK
HIZ_D_23_16 HIZ_D_15_0
DMASWP
IICSEL