参数资料
型号: Q80C32-30SHXXX:RD
厂商: TEMIC SEMICONDUCTORS
元件分类: 微控制器/微处理器
英文描述: 8-BIT, 30 MHz, MICROCONTROLLER, CQFP44
文件页数: 25/83页
文件大小: 8336K
23
8021G–AVR–03/11
ATmega329P/3290P
7.6.4
EECR – EEPROM Control Register
Bits 7:4 – Reserved
These bits are reserved bits and will always read as zero.
Bit 3 – EERIE: EEPROM Ready Interrupt Enable
Writing EERIE to one enables the EEPROM Ready Interrupt if the I bit in SREG is set. Writing
EERIE to zero disables the interrupt. The EEPROM Ready interrupt generates a constant inter-
rupt when EEWE is cleared.
Bit 2 – EEMWE: EEPROM Master Write Enable
The EEMWE bit determines whether setting EEWE to one causes the EEPROM to be written.
When EEMWE is set, setting EEWE within four clock cycles will write data to the EEPROM at
the selected address If EEMWE is zero, setting EEWE will have no effect. When EEMWE has
been written to one by software, hardware clears the bit to zero after four clock cycles. See the
description of the EEWE bit for an EEPROM write procedure.
Bit 1 – EEWE: EEPROM Write Enable
The EEPROM Write Enable Signal EEWE is the write strobe to the EEPROM. When address
and data are correctly set up, the EEWE bit must be written to one to write the value into the
EEPROM. The EEMWE bit must be written to one before a logical one is written to EEWE, oth-
erwise no EEPROM write takes place. The following procedure should be followed when writing
the EEPROM (the order of steps 3 and 4 is not essential):
1.
Wait until EEWE becomes zero.
2.
Wait until SPMEN in SPMCSR becomes zero.
3.
Write new EEPROM address to EEAR (optional).
4.
Write new EEPROM data to EEDR (optional).
5.
Write a logical one to the EEMWE bit while writing a zero to EEWE in EECR.
6.
Within four clock cycles after setting EEMWE, write a logical one to EEWE.
The EEPROM can not be programmed during a CPU write to the Flash memory. The software
must check that the Flash programming is completed before initiating a new EEPROM write.
Step 2 is only relevant if the software contains a Boot Loader allowing the CPU to program the
Flash. If the Flash is never being updated by the CPU, step 2 can be omitted. See ”Boot Loader
programming.
Caution: An interrupt between step 5 and step 6 will make the write cycle fail, since the
EEPROM Master Write Enable will time-out. If an interrupt routine accessing the EEPROM is
interrupting another EEPROM access, the EEAR or EEDR Register will be modified, causing the
interrupted EEPROM access to fail. It is recommended to have the Global Interrupt Flag cleared
during all the steps to avoid these problems.
When the write access time has elapsed, the EEWE bit is cleared by hardware. The user soft-
ware can poll this bit and wait for a zero before writing the next byte. When EEWE has been set,
the CPU is halted for two cycles before the next instruction is executed.
Bit
765
4321
0
EERIE
EEMWE
EEWE
EERE
EECR
Read/Write
R
R/W
Initial Value
0
X
0
相关PDF资料
PDF描述
Q80C32-36:R 8-BIT, 36 MHz, MICROCONTROLLER, CQFP44
Q80C32-36SHXXX:R 8-BIT, 36 MHz, MICROCONTROLLER, CQFP44
Q80C32-42:D 8-BIT, 42 MHz, MICROCONTROLLER, CQFP44
Q80C32-42:R 8-BIT, 42 MHz, MICROCONTROLLER, CQFP44
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