-`buf` string value, data to be calculated check sum in string
-`inverted_crc0` LSB of received CRC
-`inverted_crc1` MSB of received CRC
-`crc` CRC starting value (optional)
#### Returns
`bool` true, if the CRC matches; false for mismatch.
## ow.crc16()
Compute a Dallas Semiconductor 16 bit CRC. This is required to check the integrity of data received from many 1-Wire devices. Note that the CRC computed here is **not** what you'll get from the 1-Wire network, for two reasons:
1. The CRC is transmitted bitwise inverted.
2. Depending on the endian-ness of your processor, the binary representation of the two-byte return value may have a different byte order than the two bytes you get from 1-Wire.
#### Syntax
`ow.crc16(buf[, crc])`
#### Parameters
-`buf` string value, data to be calculated check sum in string.
-`crc` CRC starting value (optional)
#### Returns
`crc16` the CRC16, as defined by Dallas Semiconductor.
## ow.crc8()
Compute a Dallas Semiconductor 8 bit CRC, these are used in the ROM and scratchpad registers.
#### Syntax
`ow.crc8(buf)`
#### Parameters
`buf` string value, data to be calculated check sum in string.
#### Returns
CRC result as byte.
## ow.depower()
Stop forcing power onto the bus. You only need to do this if you used the 'power' flag to `ow.write()` or used a `ow.write_bytes()` and aren't about to do another read or write.
#### Syntax
`ow.depower(pin)`
#### Parameters
`pin` 1~12, IO index
#### Returns
`nil`
####See also
-[ow.write()](#owwrite)
-[ow.write_bytes()](#owwrite_bytes)
## ow.read()
Read a byte.
####Syntax
`ow.read(pin)`
#### Parameters
`pin` 1~12, IO index
#### Returns
Byte read from slave device.
## ow.read_bytes()
Read multi bytes.
#### Syntax
`ow.read_bytes(pin, size)`
#### Parameters
-`pin` 1~12, IO index
-`size` number of bytes to be read from slave device
#### Returns
`string` bytes read from slave device
## ow.reset_search()
Clear the search state so that it will start from the beginning again.
#### Syntax
`ow.reset_search(pin)`
#### Parameters
`pin` 1~12, IO index
#### Returns
`nil`
## ow.search()
Look for the next device.
#### Syntax
`ow.search(pin)`
#### Parameters
`pin` 1~12, IO index
#### Returns
`rom_code` string with length of 8 upon success. It contains the rom code of slave device. Returns `nil` if search was unsuccessful.
#### See also
[ow.target_search()](#owtargetsearch)
## ow.select()
Issue a 1-Wire rom select command, make sure you do the `ow.reset(pin)` first.
#### Syntax
`ow.select(pin, rom)`
#### Parameters
-`pin` 1~12, IO index
-`rom` string value, len 8, rom code of the salve device
#### Returns
`nil`
#### Example
```lua
-- 18b20 Example
pin=9
ow.setup(pin)
count=0
repeat
count=count+1
addr=ow.reset_search(pin)
addr=ow.search(pin)
tmr.wdclr()
until(addr~=nil)or(count>100)
ifaddr==nilthen
print("No more addresses.")
else
print(addr:byte(1,8))
crc=ow.crc8(string.sub(addr,1,7))
ifcrc==addr:byte(8)then
if(addr:byte(1)==0x10)or(addr:byte(1)==0x28)then
print("Device is a DS18S20 family device.")
repeat
ow.reset(pin)
ow.select(pin,addr)
ow.write(pin,0x44,1)
tmr.delay(1000000)
present=ow.reset(pin)
ow.select(pin,addr)
ow.write(pin,0xBE,1)
print("P="..present)
data=nil
data=string.char(ow.read(pin))
fori=1,8do
data=data..string.char(ow.read(pin))
end
print(data:byte(1,9))
crc=ow.crc8(string.sub(data,1,8))
print("CRC="..crc)
ifcrc==data:byte(9)then
t=(data:byte(1)+data:byte(2)*256)*625
t1=t/10000
t2=t%10000
print("Temperature="..t1.."."..t2.."Centigrade")
end
tmr.wdclr()
untilfalse
else
print("Device family is not recognized.")
end
else
print("CRC is not valid!")
end
end
```
####See also
[ow.reset()](#owreset)
## ow.setup()
Set a pin in onewire mode.
#### Syntax
`ow.setup(pin)`
#### Parameters
`pin` 1~12, IO index
#### Returns
`nil`
## ow.reset()
Perform a 1-Wire reset cycle.
#### Syntax
`ow.reset(pin)`
#### Parameters
`pin` 1~12, IO index
#### Returns
-`1` if a device responds with a presence pulse.
-`0` if there is no device or the bus is shorted or otherwise held low for more than 250 µS.
## ow.skip()
Issue a 1-Wire rom skip command, to address all on bus.
#### Syntax
`ow.skip(pin)`
#### Parameters
`pin` 1~12, IO index
#### Returns
`nil`
## ow.target_search()
Set up the search to find the device type `family_code` on the next call to `ow.search()` if it is present.
#### Syntax
`ow.target_search(pin, family_code)`
#### Parameters
-`pin` 1~12, IO index
-`family_code` byte for family code
#### Returns
`nil`
####See also
[ow.search()](#owsearch)
## ow.write()
Write a byte. If `power` is 1 then the wire is held high at the end for parasitically powered devices. You are responsible for eventually depowering it by calling `ow.depower()` or doing another read or write.
#### Syntax
`ow.write(pin, v, power)`
#### Parameters
-`pin` 1~12, IO index
-`v` byte to be written to salve device
-`power` 1 for wire being held high for parasitically powered devices
#### Returns
`nil`
####See also
[ow.depower()](#owdepower)
## ow.write_bytes()
Write multi bytes. If `power` is 1 then the wire is held high at the end for parasitically powered devices. You are responsible for eventually depowering it by calling `ow.depower()` or doing another read or write.
#### Syntax
`ow.write_bytes(pin, buf, power)`
#### Parameters
-`pin` 1~12, IO index
-`buf` string to be written to slave device
-`power` 1 for wire being held high for parasitically powered devices