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參數(shù)資料
| 型號： | MCRF250 |
| 廠商： | Microchip Technology Inc. |
| 英文描述： | 125 kHz microID Passive RFID Device with Anti-Collision |
| 中文描述： | 125千赫microID無源RFID設備與反碰撞 |
| 文件頁數(shù)： | 11/24頁 |
| 文件大?。?/td> | 395K |
| 代理商： | MCRF250 |
2003 Microchip Technology Inc.
DS21267F-page 11
MCRF250
5.0
ANTI-COLLISION
The anti-collision feature is enabled after the array lock
bit (CB12) is set. This feature relies on internal random
number oscillator/counter and special gap pulses
(= turn off RF field) provided by a reader. Figure 5-1
shows the anti-collision flowchart.
The MCRF250 works with the following anti-collision
features:
1.
The device does not output data until it sees the
first gap. (no RF field for about 60
μ
sec.)
2.
When the device sees the first gap, the internal
random number oscillator starts clocking
immediately after the gap.
3.
At the same time, the internal random number
counter starts counting the random number
clocks.
4.
The device waits for 5 bit times (about 5 msec.
for MOD128 configuration).
Example: 1 bit time=RF/128=1 msec for 128 kHz
for MOD128
5.
After the 5 bit times, the device sends data.
6.
At this time, the random number counter is still
running. If multiple tags in the field send data at
the same time, the reader will see a data
collision.
7.
When the reader sees the data collision, it sends
the second gap pulse. (no RF field for about
60
μ
sec.)
8.
After the second gap pulse, there is a chance
that the random number counter of each tag
may have a different value due to a random
variation in the oscillator’s starting time, etc.
9.
After the second gap, the random number
oscillator stops and the random number counter
will decrement at each subsequent gap.
10. The device will transmit data when its random
number counter reaches ‘
0
’.
11. The device repeats this sequence (as shown in
the flowchart in Figure 5-1) according to the
proper gap pulses provided by the reader.
Note:
Each device will output data in
different time frames since each
random number counter will arrive at
‘
0
’ at different times. As a result, the
reader can receive clean data from a
different tag in each time frame.
FIGURE 5-1:
ANTI-COLLISION
FLOWCHART
Begin
Provide Gap*
Wait 5-bit times
Is
Read Tag
Is
only one tag
modulating
modulation
present
Provide gap in the
first half of the first
bit time to make
tag stop
transmitting
No
No
Yes
Yes
Note:
*Gap = lack of RF carrier signal
= 60
μ
s ± 20%.
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相關代理商/技術參數(shù) |
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|---|---|
| MCRF250-I/P | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:125 kHz microID Passive RFID Device with Anti-Collision |
| MCRF250-I/S | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:125 kHz microID Passive RFID Device with Anti-Collision |
| MCRF250-I/SN | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:125 kHz microID Passive RFID Device with Anti-Collision |
| MCRF250-I/W | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:125 kHz microID Passive RFID Device with Anti-Collision |
| MCRF250-I/W40A | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:125 kHz microID Passive RFID Device with Anti-Collision |
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