IC-TW2_13 Datasheet, PDF (10/28 Pages) IC-Haus GmbH – 8-BIT SIN/COS INTERPOLATION IC

iC-TW2 8-BIT SIN/COS INTERPOLATION IC
WITH INTEGRATED EEPROM
DESCRIPTION OF INTERPOLATION
Rev E2, Page 10/28
iC-TW2 is a monolithic A/D converter which converts and hysteresis into angle position data. The interpola-
sine/cosine sensor signals with a selectable resolution tion function is shown in Figure 2.
Gain channel B
GC(2:0) and
GFB(1:0)
PINB
Gain channel A
GC(2:0) and
GFA(1:0)
Offset
channel A
OFSA(5:0)
Offset
channel B
OFSB(5:0)
PINA
A_U
B_V
Index pulse position IPOS(7:0)
Interpolation INTER(7:0)
(Interpolation of x5 shown)
PINZ
Z_W
Index pulse width IWIDTH(7:0)
Index pulse is disabled through pin PINZ low
Figure 2: Interpolation function
Interpolation vs. Resolution
There is a difference between interpolation factor and
resolution. Resolution (interpolation rate) is deter-
mined by the sum of edges at the incremental outputs
(AB quadrature output) within one input signal period .
Dividing the resolution by the existing edges of the
sine and cosine signals (= 4) equals to the interpola-
tion factor. The interpolation factor equals to the the
resolution divided by 4.
Example:
An interpolation factor of x8 brings a resolution of 32
(edges). To operate with an interpolation factor of 8
configure INTER(7:0) to 32.