It should be particularly emphasized that in
E20-10
not overflow alarm of ADC specified input
subrange is captured but signal level alarm output over ADC specified subrange which resulting in incorrect
presentation of this level by transmitter due to excessing conversion physical edges.
In
E20-10
of revision А when the relevant mode is selected, the ADC word size overflow
alarm is mixed in 16-bit data format in such a way that
under positive overflow the code rather more
that 8191will be issued, and under negative overflow – much less than -8192. It is understood, that on upper
level if You activate overflow alarm in software then You must use range -8192...8191 excessing events for
overflow software warning and prior to process sampled signal in your program You must limit data range
up to -8192...8191. If You apply calibration of ADC data at upper level og library function the
abovementioned principle to select overflow alarm is not changed the only difference being linear data
calibration function is applied for
E20-10
output data.
In
revision В the developers decided to abandon overflow alarm mixing in data flow and to
perform channel-by-channel warning via control pipe channel of USB
interface and relevant library
functions. Moreover, the procedure of software request on definite quantity of data from
E20-10
of
revision В has been agreed with relevant software overflow presence bit in data quan
tity requested.
5.2.7. DAC optional
Two-channel asynchronous DAC
(option) is controlled from AVR asynchronously only
using
control pipe
of USB interface and by relevant function of upper level. This means, that DAC
can be used for slow reproducing of constant voltages only under asynchronous control mode with
mean time for response - tens milliseconds, depending on response current time of computer
operating system.