Echelon I/O Model Reference for Smart Transceivers and Neuron Chips - Manual (Page 198)

188 Timer/Counter Periods and Resolution
Timer/Counter Resolution and Maximum Range
Various combinations of I/O pins can be configured as basic inputs or outputs.
The application program can optionally specify the initial values of basic outputs.
Pins configured as outputs can also be read as inputs, returning the value last
written.
The gradient behavior of the timing numbers for different Neuron Chip or Smart
Transceiver pins for some of the I/O models is due to the shift-and-mask
operation performed by the Neuron system firmware.
Series 3100 Resolution and Range
For dualslope input, edgelog input, ontime input, and period input, and infrared
input, the timer/counter returns a value (or a table of values, in the case of
edgelog input) in the range 0 to 65535, representing elapsed times from 0 up to
the maximum range given in Table 66.
For oneshot output, frequency output, and triac output, the timer/counter can be
programmed with a number in the range 0 to 65535. This number represents the
waveform ontime for oneshot output, the waveform period for frequency output,
and the control period from sync input to pulse/level output for the stretched triac
and triac output.
Table 66 gives the range and resolution for these timer/counter objects at 10 MHz
(the values scale for other clock rates; that is, for a 20 MHz device, divide the
values in the table by 2). The clock select value is specified with the clock
keyword in the declaration of the I/O object in the Neuron C application program,
and can be modified at runtime by using the io_set_clock() function.
Table 66. Series 3100 Timer/Counter Resolution and Maximum Range at 10 MHz
Dualslope, Edgelog, Ontime,
and Period Inputs; Oneshot
and Triac Outputs Frequency Output
Clock Select Resolution
Maximum
Range Resolution
Maximum
Range
0 0.2 μs 13.1 ms 0.4 μs 26.2 ms
1 0.4 μs 26.2 ms 0.8 μs 52.4 ms
2 0.8 μs 52.4 ms 1.6 μs 105 ms
3 1.6 μs 105 ms 3.2 μs 210 ms
4 3.2 μs 210 ms 6.4 μs 419 ms
5 6.4 μs 419 ms 12.8 μs 839 ms
6 12.8 μs 839 ms 25.6 μs 1678 ms