ADSP-BF50x Blackfin Processor Hardware Reference
13-9
General-Purpose Counter
DPRESCALE
= 0b10001
Zero Marker (Push Button) Operation
The
CZM
input pin can be used to sense the zero marker output of a rotary
device or to detect the pressing of a push button. There are four program-
ming schemes which are functional in all counter modes:
•
Push button mode
–This mode is enabled by setting the
CZMIE
bit
in the
CNT_IMASK
register. An active edge at the
CZM
input will set
the
CZMII
bit in the
CNT_STATUS
register. If enabled at the
system interrupt controller, this will generate an interrupt request.
The active edge is selected by the
CZMINV
bit in the
CNT_CONFIG
reg-
ister (rising edge if cleared, falling edge if set to one).
•
Zero-marker-zeros-counter mode
–This mode is enabled by setting
the
ZMZC
bit in the
CNT_CONFIG
register. An active level at the
CZM
input clears the
CNT_COUNTER
register and holds it until the
CZM
pin
is deactivated. In addition, if enabled by the
CZMZIE
bit in the
CNT_IMASK
register, it will set the
CZMZII
bit in the
CNT_STATUS
reg-
ister. If enabled by the peripheral interrupt controller, this will
generate an interrupt request. The active level is selected by the
CZMINV
bit in the
CNT_CONFIG
register (active high if cleared, active
low if set to one).
•
Zero-marker-error mode
–This mode is used to detect discrepan-
cies between counter value and the zero marker output of certain
rotary encoder devices. It is enabled by setting the
CZMEIE
bit in the
CNT_IMASK
register. When an active edge is detected at the
CZM
input pin, the four LSBs of the
CNT_COUNTER
register are compared
to zero. If they are not zero, a mismatch is signaled by way of the
CZMEII
bit in the
CNT_STATUS
register. If enabled by the peripheral
t
filter
128
131072
*7.5ns
125829
s
(approx.) 126ms
=
=
=
Summary of Contents for EZ-KIT Lite ADSP-BF506F
Page 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Page 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 804: ...Programming Examples 17 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...