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发表于 2014-9-27 20:33:35
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回复【5楼】w0rmis20:
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3.2.10 General call address
The general call address is for addressing every device connected to the I2C-bus at the
same time. However, if a device does not need any of the data supplied within the general
call structure, it can ignore this address. If a device does require data from a general call
address, it behaves as a slave-receiver. The master does not actually know how many
devices are responsive to the general call. The second and following bytes are received
by every slave-receiver capable of handling this data. A slave that cannot process one of
these bytes must ignore it. The meaning of the general call address is always specified in
the second byte (see Figure 30).
There are two cases to consider:
? When the least significant bit B is a ‘zero’
? When the least significant bit B is a ‘one’
When bit B is a ‘zero’, the second byte has the following definition:
0000 0110 (06h) — Reset and write programmable part of slave address by hardware.
On receiving this 2-byte sequence, all devices designed to respond to the general call
address reset and take in the programmable part of their address.
0000 0100 (04h) — Write programmable part of slave address by hardware. Behaves as
above, but the device does not reset.
0000 0000 (00h) — This code is not allowed to be used as the second byte.
Sequences of programming procedure are published in the appropriate device data
sheets. The remaining codes have not been fixed and devices must ignore them.
When bit B is a ‘one’, the 2-byte sequence is ignored.
这个就是介绍,不知道怎么实现啊 |
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