參數(shù)資料
型號(hào)： pic12ce674
廠商： Microchip Technology Inc.
英文描述： 8-Pin, 8-Bit CMOS Microcontroller with A/D Converter(具A/D轉(zhuǎn)換器和EEPROM數(shù)據(jù)存儲(chǔ)器的8位微控制器)
中文描述： 8引腳，8位CMOS微控制器與A / D轉(zhuǎn)換器（具的A / D轉(zhuǎn)換器和EEPROM的數(shù)據(jù)存儲(chǔ)器的8位微控制器）
文件頁數(shù)： 29/112頁
文件大?。?/td> 1205K
代理商： PIC12CE674
1998 Microchip Technology Inc.
Preliminary
DS40181A-page 29
PIC12CE67X
6.3
WRITE OPERATIONS
6.3.1
BYTE WRITE
Following the start signal from the processor, the
device code (4 bits), the don't care bits (3 bits), and the
R/W bit (which is a logic low) are placed onto the bus
by the processor. This indicates to the addressed
EEPROM that a byte with a word address will follow
after it has generated an acknowledge bit during the
ninth clock cycle. Therefore, the next byte transmitted
by the processor is the word address and will be written
into the address pointer. Only the lower four address
bits are used by the device, and the upper four bits are
don’t cares. The address byte is acknowledgeable and
the processor will then transmit the data word to be
written into the addressed memory location. The mem-
ory acknowledges again and the processor generates
a stop condition. This initiates the internal write cycle,
and during this time will not generate acknowledge sig-
nals (Figure 6-5). After a byte write command, the inter-
nal address counter will not be incremented and will
point to the same address location that was just written.
If a stop bit is transmitted to the device at any point in
the write command sequence before the entire
sequence is complete, then the command will abort
and no data will be written. If more than 8 data bits are
transmitted before the stop bit is sent, then the device
will clear the previously loaded byte and begin loading
the data buffer again. If more than one data byte is
transmitted to the device and a stop bit is sent before a
full eight data bits have been transmitted, then the write
command will abort and no data will be written. The
EEPROM memory employs a V
CC
threshold detector
circuit which disables the internal erase/write logic if
the V
CC
is below minimum VDD.
6.4
ACKNOWLEDGE POLLING
Since the EEPROM will not acknowledge during a write
cycle, this can be used to determine when the cycle is
complete (this feature can be used to maximize bus
throughput). Once the stop condition for a write com-
mand has been issued from the processor, the device
initiates the internally timed write cycle. ACK polling
can be initiated immediately. This involves the proces-
sor sending a start condition followed by the control
byte for a write command (R/W = 0). If the device is still
busy with the write cycle, then no ACK will be returned.
If no ACK is returned, then the start bit and control byte
must be re-sent. If the cycle is complete, then the
device will return the ACK and the processor can then
proceed with the next read or write command. See
Figure 6-4 for flow diagram.
FIGURE 6-4:
ACKNOWLEDGE POLLING
FLOW
Send
Write Command
Send Stop
Condition to
Initiate Write Cycle
Send Start
Send Control Byte
with R/W = 0
Did EEPROM
Acknowledge
(ACK = 0)
Next
Operation
NO
YES
FIGURE 6-5:
BYTE WRITE
S
P
BUS ACTIVITY
PROCESSOR
SDA LINE
BUS ACTIVITY
S
T
A
R
T
S
T
O
P
CONTROL
BYTE
WORD
ADDRESS
DATA
A
C
K
A
C
K
A
C
K
1
0
X
1
0
X
X
X
X = Don’t Care Bit
X
X
X
0
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
PIC12CE674/JW 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 6 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
PIC12CE674-04/JM 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:8-Pin, 8-Bit CMOS Microcontroller with A/D Converter
PIC12CE674-04/JW 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:8-Pin, 8-Bit CMOS Microcontroller with A/D Converter and EEPROM Data Memory
PIC12CE674-04/P 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 6 I/O RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
PIC12CE674-04/P 制造商:Microchip Technology Inc 功能描述:IC 8BIT CMOS MCU 12CE674 DIP8
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