SN8F2250B Series
USB 2.0 Full-Speed 8-Bit Micro-Controller
11 Flash
11.1 OVERVIEW
The SN8F2250B series USB MCU integrated device feature in-system programmable (ISP) FLASH memory for
convenient, upgradeable code storage. The FLASH memory may be programmed via the SONiX 8 bit MCU
programming interface or by application code and USB interface for maximum flexibility. The SN8F2250B provides
security options at the disposal of the designer to prevent unauthorized access to information stored in FLASH
memory.
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The MCU is stalled during Flash write (program) and erase operations, although peripherals (USB, Timers, WDT,
I/O, PWM, etc.) remain active.
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Interrupts will disable by firmware during a Flash write or erase operation.
The Flash page containing the boot loader and code option (ROM address 0x2000 ~ 0x27FF) cannot be erased
from application code when the code option’s security1 enable.
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Watch dog timer should be clear before the Flash write or erase operation.
The erase operation sets all the bits in the Flash page to logic 1.
Hardware will hold system clock and automatically move out data from RAM and do programming, after
programming finished, hardware will release system clock and let MCU execute the next instruction.(Recommend
add two NOP instructions after this active).
11.2 FLASH PROGRAMMING/ERASE CONTROL REGISTER
0BAH
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
PECMD
PECMD7
PECMD6
PECMD5
PECMD4
PECMD3
PECMD2
PECMD1
PECMD0
Read/Write
After reset
W
0
W
0
W
0
W
0
W
0
W
0
W
0
W
0
Bit [7:0] PECMD[7:0]: 0x5A: Page Program (32 words/page), 0xC3: Page Erase (128 words/page)
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