ATA6602-PLQW ATMEL [ATMEL Corporation], ATA6602-PLQW Datasheet - Page 286

• Manufacturer Part Number: ATA6602-PLQW
• Description: Microcontroller with LIN Transceiver, 5V Regulator and Watchdog
• Manufacturer: ATMEL [ATMEL Corporation]

4.23.5
4.23.5.1
286
ATA6602/ATA6603
Entering the Boot Loader Program
Store Program Memory Control and Status Register – SPMCSR
Entering the Boot Loader takes place by a jump or call from the application program. This may
be initiated by a trigger such as a command received via USART, or SPI interface. Alternatively,
the Boot Reset Fuse can be programmed so that the Reset Vector is pointing to the Boot Flash
start address after a reset. In this case, the Boot Loader is started after a reset. After the applica-
tion code is loaded, the program can start executing the application code. Note that the fuses
cannot be changed by the MCU itself. This means that once the Boot Reset Fuse is pro-
grammed, the Reset Vector will always point to the Boot Loader Reset and the fuse can only be
changed through the serial or parallel programming interface.
Table 4-105. Boot Reset Fuse
Note:
The Store Program Memory Control and Status Register contains the control bits needed to con-
trol the Boot Loader operations.
• Bit 7 – SPMIE: SPM Interrupt Enable
• Bit 6 – RWWSB: Read-While-Write Section Busy
• Bit 5 – Res: Reserved Bit
• Bit 4 – RWWSRE: Read-While-Write Section Read Enable
Initial Value
Read/Write
BOOTRST
When the SPMIE bit is written to one, and the I-bit in the Status Register is set (one), the
SPM ready interrupt will be enabled. The SPM ready Interrupt will be executed as long as
the SELFPRGEN bit in the SPMCSR Register is cleared.
When a Self-Programming (Page Erase or Page Write) operation to the RWW section is ini-
tiated, the RWWSB will be set (one) by hardware. When the RWWSB bit is set, the RWW
section cannot be accessed. The RWWSB bit will be cleared if the RWWSRE bit is written to
one after a Self-Programming operation is completed. Alternatively the RWWSB bit will
automatically be cleared if a page load operation is initiated.
This bit is a reserved bit in the ATA6602/ATA6603 and always read as zero.
When programming (Page Erase or Page Write) to the RWW section, the RWW section is
blocked for reading (the RWWSB will be set by hardware). To re-enable the RWW section,
the user software must wait until the programming is completed (SELFPRGEN will be
cleared). Then, if the RWWSRE bit is written to one at the same time as SELFPRGEN, the
next SPM instruction within four clock cycles re-enables the RWW section. The RWW sec-
tion cannot be re-enabled while the Flash is busy with a Page Erase or a Page Write
(SELFPRGEN is set). If the RWWSRE bit is written while the Flash is being loaded, the
Flash load operation will abort and the data loaded will be lost.
Bit
1
0
1. “1” means unprogrammed, “0” means programmed
SPMIE
R/W
7
0
Reset Address
Reset Vector = Application Reset (address 0x0000)
Reset Vector = Boot Loader Reset (see
RWWSB
R
6
0
(1)
R
5
–
0
RWWSRE BLBSET PGWRT
R/W
4
0
R/W
3
0
Table 4-107 on page
R/W
2
0
PGERS SELFPRGEN SPMCSR
R/W
1
0
295)
R/W
0
0
4921C–AUTO–01/07