write word with I2C

[cmisztur]

Is there a more elegant way to do this:

def writeByte(self,addess,data):
        self.i2c.writeto_mem(self.address, address, data)

def writeWord(self,address,data):
        msb = ((data & 0xFF00) >> 8)
	lsb = (data & 0x00FF)
        self.writeByte(address,msb)
        self.writeByte(address+1,lsb)

[robert-hh]

@cmisztur Instead of creating the symbols msb and lsb, you can to that calculation directly in the calls to writeByte(). That saves a little bit of memory & time, even if it makes the intention less clear.

[cmisztur]

@robert-hh so this should work?

self.i2c.writeto_mem(self.address, address, [ ((data & 0xFF00) >> 8), (data & 0x00FF)], addrsize=8 )

[robert-hh]

@cmisztur If you just want a single call, then you could also use struct:

self.i2c.writeto_mem(self.address, address, struct.pack(">H", data), addrsize=8 )

But no, I just was referring to a writeWord method:

def writeWord(self,address,data):
    self.writeByte(address,  (data  >> 8) & 0xFF)
    self.writeByte(address + 1, data & 0xFF)

That avoids the creating of two symbols & objects.

[cmisztur]

@robert-hh Thanks for the tips. I ended up doing below, which does save 32bytes over struct.pack.

self.tempBuff = bytearray(3)

def _writeWord(self,address,data):
        #self.i2c.writeto_mem(self.address, address, struct.pack(">H", data), addrsize=8 )
        self.tempBuff[0] = address
        self.tempBuff[1] = data >> 8
        self.tempBuff[2] = data & 0xff
        self.i2c.writeto(self.address, self.tempBuff)