diff options
Diffstat (limited to 'docs/library')
| -rw-r--r-- | docs/library/pyb.ADC.rst | 32 |
1 files changed, 25 insertions, 7 deletions
diff --git a/docs/library/pyb.ADC.rst b/docs/library/pyb.ADC.rst index 64848d577..36c376d37 100644 --- a/docs/library/pyb.ADC.rst +++ b/docs/library/pyb.ADC.rst @@ -63,14 +63,32 @@ Methods .. only:: port_pyboard - .. method:: adc.read_timed(buf, freq) + .. method:: adc.read_timed(buf, timer) - Read analog values into the given buffer at the given frequency. Buffer - can be bytearray or array.array for example. If a buffer with 8-bit elements - is used, sample resolution will be reduced to 8 bits. - - Example:: - + Read analog values into ``buf`` at a rate set by the ``timer`` object. + + ``buf`` can be bytearray or array.array for example. The ADC values have + 12-bit resolution and are stored directly into ``buf`` if its element size is + 16 bits or greater. If ``buf`` has only 8-bit elements (eg a bytearray) then + the sample resolution will be reduced to 8 bits. + + ``timer`` should be a Timer object, and a sample is read each time the timer + triggers. The timer must already be initialised and running at the desired + sampling frequency. + + To support previous behaviour of this function, ``timer`` can also be an + integer which specifies the frequency (in Hz) to sample at. In this case + Timer(6) will be automatically configured to run at the given frequency. + + Example using a Timer object (preferred way):: + + adc = pyb.ADC(pyb.Pin.board.X19) # create an ADC on pin X19 + tim = pyb.Timer(6, freq=10) # create a timer running at 10Hz + buf = bytearray(100) # creat a buffer to store the samples + adc.read_timed(buf, tim) # sample 100 values, taking 10s + + Example using an integer for the frequency:: + adc = pyb.ADC(pyb.Pin.board.X19) # create an ADC on pin X19 buf = bytearray(100) # create a buffer of 100 bytes adc.read_timed(buf, 10) # read analog values into buf at 10Hz |