SERIES AP48X ACROPACK
USER
’S MANUAL
Acromag, Inc. Tel: 248-295-0310
- 35 -
http://www.acromag.com
- 35 -
https://www.acromag.com
InC can be used for the Index signal. Encoders that have an index channel
can cause the counter to reload with the Counter Constant B value in a
specified phase of the quadrature cycle. Reload can be programmed to
occur in any one of the four phases in a quadrature cycle. You must ensure
that the Index channel is high during at least a portion of the phase you
specify for reload. The phase can be selected via the counter timer control
register bits 9, 8, and 7 as seen in the following Table.
InC can alternately be used as an external load of the Read Back Register.
The signal will be active high and will cause immediate load of the current
count value into the Read Back Register. An interrupt will be generated
upon hardware load of the Read Back Register (if interrupts are enabled).
Load of the Read Back Register can also be implemented by software via the
Load Read Back Register. The quadrature measurement value can be read
from the Counter Read Back Register.
Table 3.11 Counter Control
Register (Quadrature Position
Measurement)
1. The default state of the
output pin is high (output has
pullup resistor installed). Bit
3 specifies the active output
polarity when the output is
driven.
Bit(s)
FUNCTION
2,1,0
Specifies the Counter Mode:
001
Quadrature Position Measurement
3
Output Polarity (Output Pin ACTIVE Level):
0
Active LOW (Default)
1
1
Active HIGH
1
5, 4
InA / Channel A
00
Disabled (Default)
01
X1 Encoding
10
X2 Encoding
11
X4 Encoding
6
InB / Channel B
0
Disabled (Default)
1
Enabled
9,8,7
InC / Index: Channel Interrupt/Reload occurs when Index
signal=1 and the A & B input signals are as selected below.
See Control bits 14 & 13 for additional interrupt/load
control.
000
Disabled (Default) 101 and 110 also Disable
001
A = 0 , B = 1
010
A = 1 , B = 0
011
A = 1 , B = 1
100
A = 0 , B = 0
InC / Hardware Load Read Back Register
111
InC = 0: Inactive State
InC = 1: Load Read Back Register on logic high pulse
12,11,10 Counter Operational Frequency Select
000
1.953125MHz
001
3.90625MHz
010
7.8125MHz
011
15.625MHz
