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esp8266/modules/onewire: Change onewire.read() to onewire.readinto().

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This allows 1-wire drivers (eg DS18X20) to perform in-place operations and
hence do less memory allocations.
This commit is contained in:
Damien George 2016-08-29 12:27:21 +10:00
parent 9fba618356
commit 8e9b98e974
2 changed files with 6 additions and 7 deletions
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7
esp8266/modules/ds18x20.py
View File

@ -8,6 +8,7 @@ _WR_SCRATCH = const(0x4e)
class DS18X20: class DS18X20:
def __init__(self, onewire): def __init__(self, onewire):
self.ow = onewire self.ow = onewire
self.buf = bytearray(9)
def scan(self): def scan(self):
return [rom for rom in self.ow.scan() if rom[0] == 0x28] return [rom for rom in self.ow.scan() if rom[0] == 0x28]
@ -21,10 +22,10 @@ class DS18X20:
self.ow.reset(True) self.ow.reset(True)
self.ow.select_rom(rom) self.ow.select_rom(rom)
self.ow.writebyte(_RD_SCRATCH) self.ow.writebyte(_RD_SCRATCH)
buf = self.ow.read(9) self.ow.readinto(self.buf)
if self.ow.crc8(buf): if self.ow.crc8(self.buf):
raise Exception('CRC error') raise Exception('CRC error')
return buf return self.buf
def write_scratch(self, rom, buf): def write_scratch(self, rom, buf):
self.ow.reset(True) self.ow.reset(True)

6
esp8266/modules/onewire.py
View File

@ -27,11 +27,9 @@ class OneWire:
def readbyte(self): def readbyte(self):
return _ow.readbyte(self.pin) return _ow.readbyte(self.pin)
def read(self, count): def readinto(self, buf):
buf = bytearray(count) for i in range(len(buf)):
for i in range(count):
buf[i] = _ow.readbyte(self.pin) buf[i] = _ow.readbyte(self.pin)
return buf
def writebit(self, value): def writebit(self, value):
return _ow.writebit(self.pin, value) return _ow.writebit(self.pin, value)