rhubarbdog / microbit-ds18b20

a ds18b20 thermometer class

microbit-ds18b20 - a ds18b20 thermometer class

This is a class for the dallas ds18b20 thermometer it has the following methods.

read	has a single the argument, it can be READ_SCRATCH, SEARCH_ROM, ALARM_SEARCH or READ_ROM. on success 8 or 9 bytes of data is returned. If there is no data None will be returned for SEARCH commands, but will raise an exception for READ_SCRATCH and READ_ROM. Only use READ_ROM if there is *ONLY* one sensor on the wire. If there a multiple sensors when using READ_ROM they all will respond causing a data collision on the wire. With a sucessful read the ROM code of the sensor will be returned. Using the SEARCH_ROM or ALARM_SEARCH argument has to be done in a loop until no sensor responds and None is returned. READ_SCRATCH retrieves the scratchpad for further processing with the temperature or scratch_data methods
temperature	has a single argument the scratchpad, which it processes bytes 0 and 1 to create a decimal number
write_scratch	write arguments register tH, register tL and the number of bits resolution to the scratchpad adjusting the running of the device.
scratch_data	has a single argument the scratchpad and returns a list of the scratchpad data, register tH, register Tl and bits of resolution
match_rom	has a single argument the ROM code, this method signals to a ds18b20 that the next read, write or command is for it.

These methods have no arguments.

on_parasitic_power	has return True if the sensor is running on parasitic power
skip_rom	alerts all roms that the next instruction is for them to processs such as converting the temperature on all sensors simultaneously or can be used when ther is only one sensor on the wire to avoid having to match the rom before each operation.
convert	instruct the sensor to convert raw data into a temperature and write to scratchpad, this takes some time between 90ms and 750ms the sensor signals when ready, one can wait with the convert_wait method, sleep or just get on with processing knowing plenty of time will have elapsed before a read(READ_SCRATCH) method is called
convert_wait	use this method imediately after the convert method to pause processing until the ds18b20 is ready for the next operation
reset	use this method on a new powered up sensor to initialise or to correct alarm coditions or other running issues
copy_to_eprom	copies the tH and tL registers and the control byte which stores the number of bits of precission to calculate temperatures to.
cache_from_eprom	restores the registers tH and tL an the contol byte to scratchpad

An example of single operation is as follows:

sensor = DS18B20(pin0)

sensor.reset()
sensor.skip_rom()
sensor.convert()
sleep(1000)

sensor.skip_rom()
data = sensor.read(sensor.READ_SCRATCH)
print(sensor.temperature(data))

microbit-ds18b20's Issues

Does the code work?

Hy,
I tryed your code with a micro:bit V2 but nothing is happening. Did you try it with a sensor?
Thanks for your job.
Best regard
Gwendal