TS-7180 Quadrature

Quadrature Counters

The TS-7180 provides three independent quadrature counters. The associated inputs are shown in the table below.

Quadrature Quad # INPUTS Quad0 DIG_IN_1 + DIG_IN_2 Quad1 DIG_IN_3 + DIG_IN_4 Quad2 DIO_6_IN + DIO_7_IN

Each of the quadrature counters (which are in the FPGA) is 16-bits wide, and are accessed via i2c. The addresses are shown below.

Quad #	MSB	LSB	MSB Alias
Quad0	96	97	98
Quad1	99	100	101
Quad2	102	103	104

For example, to read the MSB for Quad1:

tshwctl -r -a 99

The MSB aliases are used to detect 16-bit rollover. If the first reading of the MSB is not equal to the second, overflow/underflow was detected during the read.

Edge-Counters, Period-counters

For each input pin, there is an edge-counter, and a period-counter. The former counts the positive edges on an input pin, while the latter may be used to measure the elapsed time between N positive-edges.