參數(shù)資料
型號: R5F6418JADFE
元件分類: 微控制器/微處理器
英文描述: MICROCONTROLLER, PQFP176
封裝: 24 X 24 MM, 0.50 MM PITCH, PLASTIC, LQFP-176
文件頁數(shù): 44/128頁
文件大?。?/td> 922K
代理商: R5F6418JADFE
ATmega48PA/88PA/168PA [DATASHEET]
9223F–AVR–04/14
22
The calibrated oscillator is used to time the EEPROM accesses. Table 8-2 lists the typical programming time for EEPROM
access from the CPU.
The following code examples show one assembly and one C function for writing to the EEPROM. The examples assume
that interrupts are controlled (e.g. by disabling interrupts globally) so that no interrupts will occur during execution of these
functions. The examples also assume that no flash boot loader is present in the software. If such code is present, the
EEPROM write function must also wait for any ongoing SPM command to finish.
Table 8-2.
EEPROM Programming Time
Symbol
Number of Calibrated RC Oscillator Cycles
Typ Programming Time
EEPROM write (from
CPU)
26,368
3.3ms
Assembly Code Example
EEPROM_write:
; Wait for completion of previous write
sbic
EECR,EEPE
rjmp
EEPROM_write
; Set up address (r18:r17) in address register
out
EEARH, r18
out
EEARL, r17
; Write data (r16) to Data Register
out
EEDR,r16
; Write logical one to EEMPE
sbi
EECR,EEMPE
; Start eeprom write by setting EEPE
sbi
EECR,EEPE
ret
C Code Example
void
EEPROM_write(unsigned int uiAddress, unsigned char ucData)
{
/* Wait for completion of previous write */
while(EECR & (1<<EEPE))
;
/* Set up address and Data Registers */
EEAR = uiAddress;
EEDR = ucData;
/* Write logical one to EEMPE */
EECR |= (1<<EEMPE);
/* Start eeprom write by setting EEPE */
EECR |= (1<<EEPE);
}
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