3901010407

Page 8

Aug/02

Rev. 003

PWM Generation

1) Logometers 360° ( Logo 1 and Logo 2 ):

From the angle value received from the MCU (range [0° - 89.8°]), the 10407 generates two PWM

signals (9 bit resolution) :

•

The first one represents the sine PWMSIN,

•

The second one is the cosine PWMCOS.

The 10407 uses a 512x9 ROM containing the sine of all angular values in the range [0° -89.8°]

(note that the lsb value of the angle is not used).

An angle value greater than 90° is obtained using different quadrant values :

•

Q1 (D14D15 = 00) > 0° =< a < 90°

•

Q2 (D14D15 = 01) > 90° =< a < 180°

•

Q3 (D14D15 = 10) > 180° =< a < 270°

•

Q4 (D14D15 = 11) > 270° =< a < 360°

a is the angle value

The PWM are switched to the outputs depending on the value of the quadrant :

QUADRANT

SIN1M

SIN1P

COS1M

COS1P

D14

D15

0

0

0

PWMSIN

0

PWMCOS

0

1

0

PWMCOS PWMSIN

0

1

0

PWMSIN

0

PWMCOS

0

1

1

PWMCOS

0

0

PWMSIN

•

Logometer 1 is driven by outputs SIN1M/P COS1M/P,

•

Logometer 2 is driven by outputs SIN2M/P COS2M/P.

The PWM frequency is given by :

2) Logometers 90°